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  • 1.
    Aftab, Umair
    et al.
    Mehran Univ Engn & Technol, Pakistan.
    Tahira, Aneela
    Linköping University, Department of Science and Technology, Physics, Electronics and Mathematics. Linköping University, Faculty of Science & Engineering.
    Gradone, Alessandro
    CNR IMM, Italy; Univ Bologna, Italy.
    Morandi, Vittorio
    CNR IMM, Italy.
    Abro, Muhammad Ishaq
    Mehran Univ Engn & Technol, Pakistan.
    Baloch, Muhammad Moazam
    Mehran Univ Engn & Technol, Pakistan.
    Bhatti, Adeel Liaquat
    Univ Sindh, Pakistan.
    Nafady, Ayman
    King Saud Univ, Saudi Arabia.
    Vomiero, Alberto
    Lulea Univ Technol, Sweden; Ca Foscari Univ Venice, Italy.
    Ibupoto, Zafar Hussain
    Univ Sindh, Pakistan.
    Two step synthesis of TiO2-Co3O4 composite for efficient oxygen evolution reaction2021In: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 46, no 13, p. 9110-9122Article in journal (Refereed)
    Abstract [en]

    For an active hydrogen gas generation through water dissociation, the sluggish oxygen evolution reaction (OER) kinetics due to large overpotential is a main hindrance. Herein, a simple approach is used to produce composite material based on TiO2/Co3O4 for efficient OER and overpotential is linearly reduced with increasing amount of TiO2. The scanning electron microscopy (SEM) and high resolution transmission electron microscopy (HRTEM) investigations reveal the wire like morphology of composite materials, formed by the self-assembly of nanoparticles. The titania nanoparticles were homogenously distributed on the larger Co3O4 nanoparticles. The powder x-ray diffraction revealed a tetragonal phase of TiO2 and the cubic phase of Co3O4 in the composite materials. Composite samples with increasing TiO2 content were obtained (18%, 33%, 41% and 65% wt.). Among the composites, cobalt oxide-titanium oxide with the highest TiO2 content (CT-20) possesses the lowest overpotential for OER with a Tafel slope of 60 mV dec(-1) and an exchange current density of 2.98 x 10(-3)A/cm(2). The CT-20 is highly durable for 45 h at different current densities of 10, 20 and 30 mA/cm(2). Electrochemical impedance spectroscopy (EIS) confirmed the fast charge transport for the CT-20 sample, which potentially accelerated the OER kinetics. These results based on a two-step methodology for the synthesis of TiO2/Co3O4 material can be useful and interesting for various energy storage and energy conversion systems. (C) 2021 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

  • 2.
    Aftab, Umair
    et al.
    Mehran Univ Engn and Technol, Pakistan.
    Tahira, Aneela
    Linköping University, Department of Science and Technology, Physics, Electronics and Mathematics. Linköping University, Faculty of Science & Engineering.
    Mazzaro, Raffaello
    Italian Natl Res Council, Italy.
    Abro, Muhammad Ishaq
    Mehran Univ Engn and Technol, Pakistan.
    Baloch, Muhammad Moazam
    Mehran Univ Engn and Technol, Pakistan.
    Willander, Magnus
    Linköping University, Department of Science and Technology, Physics, Electronics and Mathematics. Linköping University, Faculty of Science & Engineering.
    Nur, Omer
    Linköping University, Department of Science and Technology, Physics, Electronics and Mathematics. Linköping University, Faculty of Science & Engineering.
    Yu, Cong
    Chinese Acad Sci, Peoples R China.
    Ibupoto, Zafar Hussain
    Univ Sindh, Pakistan.
    The chemically reduced CuO-Co3O4 composite as a highly efficient electrocatalyst for oxygen evolution reaction in alkaline media2019In: Catalysis Science & Technology, ISSN 2044-4753, E-ISSN 2044-4761, Vol. 9, no 22, p. 6274-6284Article in journal (Refereed)
    Abstract [en]

    The fabrication of efficient, alkaline-stable and nonprecious electrocatalysts for the oxygen evolution reaction is highly needed; however, it is a challenging task. Herein, we report a noble metal-free advanced catalyst, i.e. the chemically reduced mixed transition metal oxide CuO-Co3O4 composite, with outstanding oxygen evolution reaction activity in alkaline media. Sodium borohydride (NaBH4) was used as a reducing agent for the mixed transition metal oxide CuO-Co3O4. The chemically reduced composite carried mixed valence states of Cu and Co, which played a dynamic role in driving an excellent oxygen evolution reaction process. The X-ray photo-electron spectroscopy (XPS) study confirmed high density of active sites in the treated sample with a large number of oxygen vacancies. The developed electrocatalyst showed the lowest overpotential of 144.5 mV vs. the reversible hydrogen electrode (RHE) to achieve the current density of 40 mA cm(-2) and remained stable for 40 hours throughout the chronoamperometry test at the constant potential of 1.39 V vs. RHE. Moreover, the chemically reduced composite was highly durable. Electrochemical impedance spectroscopy (EIS) confirmed the low charge transfer resistance of 13.53 ohms for the chemically reduced composite, which was 50 and 26 times smaller than that of Co3O4 and untreated CuO-Co3O4, respectively. The electrochemically active surface area for the chemically reduced composite was found to be greater than that for pristine CuO, Co3O4 and untreated pristine CuO-Co3O4. These findings reveal the possibility of a new gateway for the capitalization of a chemically reduced sample into diverse energy storage and conversion systems such as lithium-ion batteries and supercapacitors.

  • 3.
    Aftab, Umair
    et al.
    Mehran Univ Engn and Technol, Pakistan.
    Tahira, Aneela
    Linköping University, Department of Science and Technology, Physics, Electronics and Mathematics. Linköping University, Faculty of Science & Engineering.
    Mazzaro, Raffaello
    Italian Natl Res Council, Italy.
    Morandi, Vittorio
    Italian Natl Res Council, Italy.
    Abro, Muhammad Ishaq
    Mehran Univ Engn and Technol, Pakistan.
    Baloch, Muhammad Moazam
    Mehran Univ Engn and Technol, Pakistan.
    Yu, Cong
    Chinese Acad Sci, Peoples R China.
    Ibupoto, Zafar Hussain
    Univ Sindh, Pakistan.
    Nickel-cobalt bimetallic sulfide NiCo(2)S(4)nanostructures for a robust hydrogen evolution reaction in acidic media2020In: RSC Advances, E-ISSN 2046-2069, RSC ADVANCES, Vol. 10, no 37, p. 22196-22203Article in journal (Refereed)
    Abstract [en]

    There are many challenges associated with the fabrication of efficient, inexpensive, durable and very stable nonprecious metal catalysts for the hydrogen evolution reaction (HER). In this study, we have designed a facile strategy by tailoring the concentration of precursors to successfully obtain nickel-cobalt bimetallic sulfide (NiCo2S4) using a simple hydrothermal method. The morphology of the newly prepared NiCo(2)S(4)comprised a mixture of microparticles and nanorods, which were few microns in dimension. The crystallinity of the composite sample was found to be excellent with a cubic phase. The sample that contained a higher amount of cobalt compared to nickel and produced single-phase NiCo(2)S(4)exhibited considerably improved HER performance. The variation in the salt precursor concentration during the synthesis of a material is a simple methodology to produce a scalable platinum-free catalyst for HER. The advantageous features of the multiple active sites of cobalt in the CN-21 sample as compared to that for pristine CoS and NiS laid the foundation for the provision of abundant active edges for HER. The composite sample produced a current density of 10 mA cm(-2)at an overpotential of 345 mV. Also, it exhibited a Tafel value of 60 mV dec(-1), which predominantly ensured rapid charge transfer kinetics during HER. CN-21 was highly durable and stable for 30 hours. Electrochemical impedance spectroscopy showed that the charge transfer resistance was 21.88 ohms, which further validated the HER polarization curves and Tafel results. CN-21 exhibited a double layer capacitance of 4.69 mu F cm(-2)and a significant electrochemically active surface area of 134.0 cm(2), which again supported the robust efficiency for HER. The obtained results reveal that our developed NiCo(2)S(4)catalyst has a high density of active edges, and it is a non-noble metal catalyst for the hydrogen evolution reaction. The present findings provide an alternative strategy and an active nonprecious material for the development of energy-related applications.

  • 4.
    Aftab, Umair
    et al.
    Mehran Univ Engn and Technol, Pakistan.
    Tahira, Aneela
    Linköping University, Department of Science and Technology, Physics, Electronics and Mathematics. Linköping University, Faculty of Science & Engineering.
    Samo, Abdul Hanan
    Mehran Univ Engn and Technol, Pakistan.
    Abro, Muhammad Ishaq
    Mehran Univ Engn and Technol, Pakistan.
    Baloch, Muhammad Moazam
    Mehran Univ Engn and Technol, Pakistan.
    Kumar, Mukesh
    Mehran Univ Engn and Technol, Pakistan.
    Sirajuddin,
    Univ Sindh Jamshoro, Pakistan.
    Ibupoto, Zafar Hussain
    Univ Sindh Jamshoro, Pakistan.
    Mixed CoS2@Co3O4 composite material: An efficient nonprecious electrocatalyst for hydrogen evolution reaction2020In: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 45, no 27, p. 13805-13813Article in journal (Refereed)
    Abstract [en]

    Hydrogen evolution reaction (HER) has been identified as a sustainable and environment friendly technology for a wide range of energy conversion and storage applications. The big barrier in realizing this green technology requires a highly efficient, earth-abundant, and low-cost electrocatalyst for HER. Various HER catalysts have been designed and reported, still, their performance is not up to the mark of Pt. Among them, cobalt-based, especially cobalt disulfide (CoS2) has shown significant HER activity and found suitable candidature for HER due to its low cost, simple to prepare, and exhibits good stability. Herein, we synthesized various nanostructured materials including pure CoS2, Co3O4 and their composites by wet chemical methods and found them active for HER. The scanning electron microscopy (SEM) has revealed a morphology of composite as a mixture of nanowires and round shape spherical nanoparticles with several microns in dimension. The X-ray diffraction (XRD) confirmed the cubic phase of CoS2 and cubic phase of Co3O4 in the composite materials. The chemical deposition of CoS2 onto Co3O4 has tailored the HER activity of CoS2@Co3O4 composite material. Two CoS2@Co3O4 composite materials were produced with varying amounts of Co3O4 and labeled as samples 1 and 2. The Co3O4 reduced the adsorption energy for hydrogen, decreased the aggregation of CoS2 and uplifted the stability of CoS2@Co3O4 a composite material in alkaline media. Sample 1 requires an overpotential of 320 mV to reach a current density of 10 mA/cm(2) and it exhibits a Tafel slope of 42 mVdec(-1) which is the key indicator for the fast HER kinetics on sample 1. The sample 1 is highly durable for 50 h and also it has excellent stability. The electrochemical impedance spectroscopy (EIS) revealed a small charge transfer resistance of 28.81 Ohms for the sample 1 with high capacitance double-layer value of 0.81 mF. EIS has supported polarization and Tafel slope results. Based on the partial physical characterization and the electrochemical results, the as-obtained sample 1 (CoS2@Co3O4 composite material) will find potential applications in an extended range of energy conversion and storage devices owing to its low cost, high abundance, and excellent efficiency. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

  • 5.
    Ahmed Khand, Aftab
    et al.
    Tsinghua Univ Beijing, Peoples R China; Univ Sindh Jamshoro, Pakistan.
    Ahmed Lakho, Saeed
    Univ Karachi, Pakistan.
    Tahira, Aneela
    Linköping University, Department of Science and Technology, Physics, Electronics and Mathematics. Linköping University, Faculty of Science & Engineering.
    Ahmed, Mansoor
    Univ Karachi, Pakistan.
    Aftab, Umair
    MUET, Pakistan.
    Abro, Muhammad Ishaq
    MUET, Pakistan.
    Juno, Awais Ahmed
    Ziauddin Univ, Pakistan.
    Nafady, Ayman
    King Saud Univ, Saudi Arabia.
    Ibupoto, Zafar Hussain
    Univ Sindh Jamshoro, Pakistan.
    Synthesis of Sheet Like Nanostructures of NiO Using Potassium Dichromate as Surface Modifying Agent for the Sensitive and Selective Determination of Amlodipine Besylate (ADB) Drug2021In: Electroanalysis, ISSN 1040-0397, E-ISSN 1521-4109, Vol. 33, no 5, p. 1121-1128Article in journal (Refereed)
    Abstract [en]

    The monitoring of hypertension drugs is very critical and important to sustain a healthy life. In this study, we have synthesized nickel oxide (NiO) nanostructures using potassium dichromate as surface modifying agent by hydrothermal method. These NiO nanostructures were found highly active for the oxidation of ADB besylate (ADB). The unit cell structure and morphology were investigated by scanning electron microscopy (SEM) and powder X-ray diffraction (XRD) techniques. The SEM study has confirmed the nano sheet like morphology and XRD analysis has described the cubic unit arrays of NiO. After the physical characterization, NiO nanostructures were used to modify the surface of glassy carbon electrode (GCE) by drop casting method. Then cyclic voltammetry (CV) was used to characterize the electrochemical activity of NiO nanostructures in the0.1 M phosphate buffer solution of pH 10.0 and a well resolved oxidation peak was identified at 0.70 V. The linear range for the NiO nanostructures was observed from 20-90 nM with a regression coefficient of 0.99 using CV. The calculated limit of detection (LOD) was 2.125 nM and the limit of quantification (LOQ) was 4.08 nM. Further to validate the CV calibration plot, an amperometry experiment was performed on the NiO nanostructures and sensors exhibited a linear range of 10 nM to 115 nM with LOD of 1.15 nM. The proposed approach was successfully used for the determination of ADB from commercial tablets and it reveals that the sensor could be capitalized to monitor ADB concentrations from pharmaceutical products. The use of potassium dichromate as a surface modifying agent for the metal oxide nanostructures may be of great interest to manipulate their crystal and surface properties for the extended range of biomedical and energy related applications.

  • 6.
    Amin, Sidra
    et al.
    Univ Sindh, Pakistan; Shaheed Benazir Bhutto Univ, Pakistan.
    Tahira, Aneela
    Linköping University, Department of Science and Technology, Physics, Electronics and Mathematics. Linköping University, Faculty of Science & Engineering.
    Solangi, Amber
    Univ Sindh, Pakistan.
    Nafady, Ayman
    King Saud Univ, Saudi Arabia.
    Ibupoto, Zafar Hussain
    Univ Sindh, Pakistan.
    MoSx-Co3O4 Nanocomposite for Selective Determination of Ascorbic Acid2021In: Journal of Nanoscience and Nanotechnology, ISSN 1533-4880, E-ISSN 1533-4899, Vol. 21, no 4, p. 2595-2603Article in journal (Refereed)
    Abstract [en]

    Designing a nanocomposite with sensitive and selective determination of ascorbic acid is challenging task. It is possible through the exploitation of attractive features of nanoscience and nanotechnology for the synthesis of nanostructured materials. Herein, we report the decoration of nanoparticle of MoSx on the surface of Co3O4 nanowires by hydrothermal method. The MoSx nanoparticles shared the large surface on the Co3O4 nanowires, thus it supported in the development enzyme free ascorbic acid sensor. Non-enzymatic sensor based on MoSx-Co3O4 composite was found very selective for the determination of ascorbic acid (AA) in phosphate buffer solution of pH 7.4. The MoSx-Co3O4 nanocomposite was used to modify the glassy carbon electrode to measure AA from variety of practical samples. The MoSx-Co3O4 nanocomposite was used to modify the glassy carbon electrode and it has shown the attractive analytical features such as a low working potential +0.3 V, linear range of concentration from 100-7000 mu M, low limit of detection 14 mu M, and low limit of quantification (LOQ) of 42 mu M. The developed sensor is highly selective and stable. Importantly, it was applied successfully for the practical applications such as detection of AA from grapefruit, tomato and lemon juice. The excellent electrochemical properties of fabricated MoSx-Co3O4 nanocomposite can be attributed to the increasing electro active surface area of MoSx. The presented nanocomposite is earth abundant, environment friendly and inexpensive and it holds promising features for the selective and sensitive determination of AA from practical applications. The nanocomposite can be capitalized into the wide range of biomedical applications.

  • 7.
    Bhatti, Adeel Liaquat
    et al.
    Univ Sindh, Pakistan.
    Aftab, Umair
    Mehran Univ Engn & Technol, Pakistan.
    Tahira, Aneela
    Linköping University, Department of Science and Technology, Physics, Electronics and Mathematics. Linköping University, Faculty of Science & Engineering.
    Abro, Muhammad Ishaq
    Mehran Univ Engn & Technol, Pakistan.
    Mari, Riaz Hussain
    Univ Sindh, Pakistan.
    Samoon, Muhammad Kashif
    Univ Sindh, Pakistan.
    Aghem, Muhammad Hassan
    Univ Sindh, Pakistan.
    Shaikh, Nek Muhammad
    Univ Sindh, Pakistan.
    Mugheri, Abdul Qayoom
    Univ Sindh, Pakistan.
    Ibupoto, Zafar Hussain
    Univ Sindh, Pakistan.
    An Efficient and Functional Fe3O4/Co3O4 Composite for Oxygen Evolution Reaction2021In: Journal of Nanoscience and Nanotechnology, ISSN 1533-4880, E-ISSN 1533-4899, Vol. 21, no 4, p. 2675-2680Article in journal (Refereed)
    Abstract [en]

    The design of efficient, stable, durable and noble metal free electro catalysts for oxygen evolution reaction (OER) are of immediate need, but very challenging task. In this study, iron induction into cobalt oxide (Co3O4) has resulted composite structure by wet chemical method. The iron impurity has brought an electronic disorder into Fe3O4/cobalt oxide composite thereby efficient oxygen evolution reaction is demonstrated. An addition of iron content into composite resulted the alternation of morphology from Nano rods to clusters of nanoparticles. The successive addition of iron into composite system reduced the onset potential of OER as compared to the pristine cobalt oxide. A Tafel slope of 80 mVdec(-1) indicates the favorable oxygen evolution reaction kinetics on the sample 4. An over-potential of 370 mV is required to reach a 10 mAcm(-2) current density which is acceptable for a nonprecious catalyst. The catalyst is highly durable and stable for 30 hours. Electrochemical impedance spectroscopy further provided a deeper insight on charge transfer resistance and sample 4 has low charge transfer resistance that supported the OER polarization curves. The sample 4 has more electrochemical active surface area of 393.5 cm(2). These obtained results are exciting and highlighting the importance of composite structure and leave a huge space for the future investigations on composite materials for energy related applications.

  • 8.
    Bhatti, Adeel Liaquat
    et al.
    Univ Sindh, Pakistan.
    Aftab, Umair
    Mehran Univ Engn and Technol, Pakistan.
    Tahira, Aneela
    Linköping University, Department of Science and Technology, Physics, Electronics and Mathematics. Linköping University, Faculty of Science & Engineering.
    Abro, Muhammad Ishaq
    Mehran Univ Engn and Technol, Pakistan.
    Samoon, Muhammad Kashif
    Ctr Pure and Appl Geol Univ Sindh, Pakistan.
    Aghem, Muhammad Hassan
    Ctr Pure and Appl Geol Univ Sindh, Pakistan.
    Bhatti, Muhamad Ali
    Ctr Environm Sci, Pakistan.
    HussainIbupoto, Zafar
    Univ Sindh, Pakistan.
    Facile doping of nickel into Co3O4 nanostructures to make them efficient for catalyzing the oxygen evolution reaction2020In: RSC Advances, E-ISSN 2046-2069, RSC ADVANCES, Vol. 10, no 22, p. 12962-12969Article in journal (Refereed)
    Abstract [en]

    Designing a facile and low-cost methodology to fabricate earth-abundant catalysts is very much needed for a wide range of applications. Herein, a simple and straightforward approach was developed to tune the electronic properties of cobalt oxide nanostructures by doping them with nickel and then using them to catalyze the oxygen evolution reaction (OER) in an aqueous solution of 1.0 M KOH. The addition of a nickel impurity improved the conductivity of the cobalt oxide, and further increased its activity towards the OER. Analytical techniques such as scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and powder X-ray diffraction (XRD) were used to investigate, respectively, the morphology, composition and crystalline structure of the materials used. The nickel-doped cobalt oxide material showed randomly oriented nanowires and a high density of nanoparticles, exhibited the cubic phase, and contained cobalt, nickel and oxygen as its main elements. The nickel-doped cobalt oxide also yielded a Tafel slope of 82 mV dec(-1) and required an overpotential of 300 mV to reach a current density of 10 mA cm(-2). As an OER catalyst, it was shown to be durable for 40 h. Electrochemical impedance spectroscopy (EIS) analysis showed a low charge-transfer resistance of 177.5 ohms for the nickel-doped cobalt oxide, which provided a further example of its excellent OER performance. These results taken together indicated that nickel doping of cobalt oxide can be accomplished via a facile approach and that the product of this doping can be used for energy and environmental applications.

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  • 9.
    Bhatti, Muhammad Ali
    et al.
    Univ Sindh Jamshoro, Pakistan.
    Almaani, Khalida Faryal
    Univ Sindh Jamshoro, Pakistan.
    Shah, Aqeel Ahmed
    NED Univ Engn & Technol, Pakistan.
    Tahira, Aneela
    Linköping University, Department of Science and Technology, Physics, Electronics and Mathematics. Linköping University, Faculty of Science & Engineering.
    Chandio, Ali Dad
    NED Univ Engn & Technol, Pakistan.
    Mugheri, Abdul Qayoom
    Univ Sindh Jamshoro, Pakistan.
    Bhatti, Adeel liaquat
    Univ Sindh Jamshoro, Pakistan.
    Waryani, Baradi
    Univ Sindh Jamshoro, Pakistan.
    Medany, Shymaa S.
    Cairo Univ, Egypt.
    Nafady, Ayman
    King Saud Univ, Saudi Arabia.
    Ibupoto, Zafar Hussain
    Univ Sindh Jamshoro, Pakistan.
    Low Temperature Aqueous Chemical Growth Method for the Doping of W into ZnO Nanostructures and Their Photocatalytic Role in the Degradration of Methylene Blue2022In: Journal of cluster science, ISSN 1040-7278, E-ISSN 1572-8862, Vol. 33, no 4, p. 1445-1456Article in journal (Refereed)
    Abstract [en]

    In this research work, we have produced tungsten (W) doped ZnO nanostructures via low-temperature aqueous chemical growth method. The morphology, crystal arrays and composition was investigated by scanning electron microscopy (SEM), powder X-ray diffraction (XRD) and energy dispersive X-rays (EDX) respectively. The SEM results indicate the nanowire morphology before and after the doping of W into ZnO and XRD study has shown the hexagonal crystallography of W doped ZnO samples. The EDX study has confirmed the successful doping of W into ZnO crystal lattices. The photodegradation performance of methylene blue was evaluated with W doped ZnO samples and pristine ZnO in aqueous solution. The measured degradation efficiencies for the different W doped ZnO samples were 5 wt%, 10 wt%, 15 wt% and 20 wt% at pH 5 are 87.8%, 92.3%, 92.8% and 96.9%), at pH 9 (72.1%, 90.7%, 92.1%, and 96.4%) and at pH 11 (80%, 85%, 87% and 89%) for the time interval of 90 min respectively. The pH of dye solution has significant effect on the degradation efficiency. These findings show that the W doped ZnO samples have superior degradation efficiency of 96.6% in a very short interval of time. The swift degradation kinetics for the W doped ZnO samples is attributed to the reduction in the energy band gap, decrease in particle size, enhanced surface area, decrease in the recombination rate and foster charge separation process. The obtained results are exciting and providing efficient earth-abundant photocatalysts for the energy and environmental purposes.Kindly confirm the Given names and Family names for all the authors.They are correct.

  • 10.
    Bhatti, Muhammad Ali
    et al.
    Univ Sindh Jamshoro, Pakistan.
    Shah, Aqeel Ahmed
    Univ Engn & Technol Karachi, Pakistan.
    Almaani, Khalida Faryal
    Univ Sindh Jamshoro, Pakistan.
    Tahira, Aneela
    Linköping University, Department of Science and Technology, Physics, Electronics and Mathematics. Linköping University, Faculty of Science & Engineering.
    Chandio, Ali Dad
    Univ Engn & Technol Karachi, Pakistan.
    Willander, Magnus
    Linköping University, Department of Science and Technology, Physics, Electronics and Mathematics. Linköping University, Faculty of Science & Engineering.
    Nur, Omer
    Linköping University, Department of Science and Technology, Physics, Electronics and Mathematics. Linköping University, Faculty of Science & Engineering.
    Mugheri, Abdul Qayoom
    Univ Sindh Jamshoro, Pakistan.
    Bhatti, Adeel Liaquat
    Univ Sindh Jamshoro, Pakistan.
    Waryani, Baradi
    Univ Sindh Jamshoro, Pakistan.
    Nafady, Ayman
    King Saud Univ, Saudi Arabia.
    Ibupoto, Zafar Hussain
    Univ Sindh Jamshoro, Pakistan.
    TiO2/ZnO Nanocomposite Material for Efficient Degradation of Methylene Blue2021In: Journal of Nanoscience and Nanotechnology, ISSN 1533-4880, E-ISSN 1533-4899, Vol. 21, no 4, p. 2511-2519Article in journal (Refereed)
    Abstract [en]

    In this research work, we have produced a composite material consisting titanium dioxide (TiO2) and zinc oxide (ZnO) nanostructures via precipitation method. Scanning electron microscopy (SEM) study has shown the mixture of nanostructures consisting nanorods and nano flower. Energy dispersive spectroscopy (EDS) study has confirmed the presence of Ti, Zn and O as main elements in the composite. X-ray diffraction (XID) study has revealed that the successful presence of TiO2 and ZnO in the composite. The composite material exhibits small optical energy band gap which led to reduction of the charge recombination rate of electron-hole pairs. The band gap for the composite TiO2/ZnO samples namely 1, 2, 3 and 4 is 3.18, 3.00, 2.97 and 2.83 eV respectively. Small optical bandgap gives less relaxation time for the recombination of electron and hole pairs, thus favorable photodegradation is found. The degradation efficiency for the TiO2/ZnO samples for methylene blue in order of 55.03%, 75.7%, 85.14% and 90.08% is found for the samples 1, 2, 3 and 4 respectively. The proposed study of titanium dioxide addition into ZnO is facile and inexpensive for the development of efficient photocatalysts. This can be capitalized at large scale for the energy and environmental applications.

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  • 11.
    Bhatti, Muhammad Ali
    et al.
    Univ Sindh Jamshoro, Pakistan.
    Shah, Aqeel Ahmed
    NED Univ Engn and Technol Karachi, Pakistan.
    Almani, Khalida Faryal
    Univ Sindh Jamshoro, Pakistan.
    Tahira, Aneela
    Linköping University, Department of Science and Technology, Physics, Electronics and Mathematics. Linköping University, Faculty of Science & Engineering.
    Chalangar, Ebrahim
    Linköping University, Department of Science and Technology, Physics, Electronics and Mathematics. Linköping University, Faculty of Science & Engineering.
    Chandio, Ali Dad
    NED Univ Engn and Technol Karachi, Pakistan.
    Nur, Omer
    Linköping University, Department of Science and Technology, Physics, Electronics and Mathematics. Linköping University, Faculty of Science & Engineering.
    Willander, Magnus
    Linköping University, Department of Science and Technology, Physics, Electronics and Mathematics. Linköping University, Faculty of Science & Engineering.
    Ibupoto, Zafar Hussain
    Univ Sindh Jamshoro, Pakistan.
    Efficient photo catalysts based on silver doped ZnO nanorods for the photo degradation of methyl orange2019In: Ceramics International, ISSN 0272-8842, E-ISSN 1873-3956, Vol. 45, no 17, p. 23289-23297Article in journal (Refereed)
    Abstract [en]

    In this study, the doped ZnO nanorods with silver (Ag) as photosensitive material are prepared by the solvothermal method. The structural and optical characterization is carried out by the scanning electron microscopy, X-ray diffraction, energy dispersive spectroscopy and UV-visible spectroscopy. The use of Ag as dopant did not alter the morphology of ZnO except sample 4 which has flower like morphology. The Ag, Zn and O are the main constituent of doped materials. The XRD revealed a hexagonal phase for ZnO and cubic phase for silver and confirmed the successful doping of Ag. The photocatalytic activity of Ag doped ZnO nanorods was investigated for the photo degradation of methyl orange. The photocatalytic measurements show that 88% degradation of methyl orange by the sample 4 within the 2 h of UV light treatment (365 nm) is significant advancement in the photocatalyst and provide the inexpensive and promising materials for the photochemical applications.

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  • 12.
    Bhatti, Muhammad Ali
    et al.
    Univ Sindh Jamshoro, Pakistan.
    Tahira, Aneela
    Linköping University, Department of Science and Technology, Physics, Electronics and Mathematics. Linköping University, Faculty of Science & Engineering.
    Chandio, Ali dad
    NED Univ Engn & Technol Karachi, Pakistan.
    Almani, Khalida Faryal
    Univ Sindh Jamshoro, Pakistan.
    Bhatti, Adeel Liaquat
    Univ Sindh Jamshoro, Pakistan.
    Waryani, Baradi
    Univ Sindh Jamshoro, Pakistan.
    Nafady, Ayman
    King Saud Univ, Saudi Arabia.
    Ibupoto, Zafar Hussain
    Univ Sindh Jamshoro, Pakistan.
    Enzymes and phytochemicals from neem extract robustly tuned the photocatalytic activity of ZnO for the degradation of malachite green (MG) in aqueous media2021In: Research on chemical intermediates (Print), ISSN 0922-6168, E-ISSN 1568-5675, Vol. 47, no 4, p. 1581-1599Article in journal (Refereed)
    Abstract [en]

    The malachite green (MG) is very difficult to degrade in water; thus, it needs an efficient photocatalyst. In this study, neem extract was used to tune the surface and crystal properties of ZnO nanostructures for the photodegradation of MG. The biosynthesized ZnO samples were prepared by hydrothermal method in the presence of 5, 10 and 15 mL of neem extract. The structural characterization has shown nanoparticle like morphology of ZnO as revealed by scanning electron microscopy (SEM) and hexagonal phase was confirmed by powder X-ray diffraction (XRD) technique. The XRD analysis has shown a shift in the 2 theta towards lower angle for ZnO with increasing amount of neem extract. Also, the crystallite particle size of ZnO was decreased with increasing neem extract. The UV-visible spectroscopy has shown the decrease in the optical band gap of ZnO, and the lowest band gap is possessed by ZnO sample produced with 15 mL of neem extract. The ZnO sample obtained with 15 mL of neem extract has shown approximately 99% degradation efficiency for MG for 70 min in aqueous solution. The superior photocatalytic activity of ZnO sample with 15 mL of neem extract could be attributed from the decrease in charge recombination rate due to the decreased optical band gap and particle size.

  • 13.
    Ibupoto, Zafar Hussain
    et al.
    Chinese Acad Sci, Peoples R China; Univ Sindh, Pakistan.
    Tahira, Aneela
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Raza, Hamid
    Univ Medial and Hlth Sci, Pakistan.
    Ali, Gulzar
    Univ Sindh, Pakistan.
    Khand, Aftab Ahmed
    Tsinghua Univ, Peoples R China.
    Jilani, Nabila Shah
    Univ Sindh, Pakistan.
    Mallah, Arfana Begum
    Univ Sindh, Pakistan.
    Yu, Cong
    Chinese Acad Sci, Peoples R China.
    Willander, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Synthesis of Heart/Dumbbell-Like CuO Functional Nanostructures for the Development of Uric Acid Biosensor2018In: Materials, E-ISSN 1996-1944, Vol. 11, no 8, article id 1378Article in journal (Refereed)
    Abstract [en]

    It is always demanded to prepare a nanostructured material with prominent functional properties for the development of a new generation of devices. This study is focused on the synthesis of heart/dumbbell-like CuO nanostructures using a low-temperature aqueous chemical growth method with vitamin B-12 as a soft template and growth directing agent. CuO nanostructures are characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) techniques. CuO nanostructures are heart/dumbbell like in shape, exhibit high crystalline quality as demonstrated by XRD, and have no impurity as confirmed by XPS. Apparently, CuO material seems to be porous in structure, which can easily carry large amount of enzyme molecules, thus enhanced performance is shown for the determination of uric acid. The working linear range of the biosensor is 0.001 mM to 10 mM with a detection limit of 0.0005 mM and a sensitivity of 61.88 mV/decade. The presented uric acid biosensor is highly stable, repeatable, and reproducible. The analytical practicality of the proposed uric acid biosensor is also monitored. The fabrication methodology is inexpensive, simple, and scalable, which ensures the capitalization of the developed uric acid biosensor for commercialization. Also, CuO material can be used for various applications such as solar cells, lithium ion batteries, and supercapacitors.

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  • 14.
    Khokhar, Shams Parveen
    et al.
    Univ Sindh Jamshoro, Pakistan.
    Abbasi, Mazhar Ali
    Univ Sindh Jamshoro, Pakistan.
    Aftab, Umair
    Mehran Univ Engn & Technol, Pakistan.
    Abro, Muhammad Ishaq
    Mehran Univ Engn & Technol, Pakistan.
    Shah, Aqeel Ahmed
    NED Univ Engn Sci & Technol, Pakistan.
    Chandio, Ali Dad
    NED Univ Engn Sci & Technol, Pakistan.
    Bhatti, Adeel Liaquat
    Univ Sindh Jamshoro, Pakistan.
    Tahira, Aneela
    Linköping University, Department of Science and Technology, Physics, Electronics and Mathematics. Linköping University, Faculty of Science & Engineering.
    Ibupoto, Zafar Hussain
    Univ Sindh Jamshoro, Pakistan.
    An Efficient Nickel Sulfide@NiO Nanocomposite Catalyst with High Density of Active Sites for the Hydrogen Evolution Reaction in Alkaline Media2021In: Journal of Nanoscience and Nanotechnology, ISSN 1533-4880, E-ISSN 1533-4899, Vol. 21, no 4, p. 2520-2528Article in journal (Refereed)
    Abstract [en]

    Efficient hydrogen evolution reaction (HER) catalysts based on the earth-abundant materials are highly vital to design practical and environmentally friendly water splitting devices. In this study, we present an optimized strategy for the development of active catalysts for hydrogen evolution reaction HER. The composite catalysts are prepared with the nanosurface of NiO for the deposition of NiS by hydrothermal method. In alkaline electrolyte, the NIS/NiO nanocomposite has shown excellent catalytic HER properties at the low onset potential and small Tafel slope of 72 mV dec(-1). A current density of 10 mA/cm(2) is achieved by the nanocomposite obtained with 0.4 gram of NiO as nanosurface for the deposition of NiS (sample 4) at the cost of 429 mV versus RHE. The sample 4 carries more active sites that allow it to act as excellent HER catalyst. Based on this study, we conclude that increasing the nickel oxide content into composite sample facilitates the HER process. Additionally, a long term HER stability for 10 hours and good durability is also demonstrated by the sample 4. Our findings reveal that the optimization of nickel oxide content in the preparation of catalyst leads to the excellent HER activity for the design of practical water splitting devices and other related applications.

  • 15.
    Lal, Ramesh
    et al.
    Shah Abdul Latif Univ, Pakistan.
    Bhatti, Muhammad Ali
    Univ Sindh Jamshoro, Pakistan.
    Shahzad, Ghazala
    Liaquat Univ Med & Hlth Sci, Pakistan.
    Tahira, Aneela
    Linköping University, Department of Science and Technology, Physics, Electronics and Mathematics. Linköping University, Faculty of Science & Engineering.
    Panhwar, Mahjabeen
    Univ Sindh, Pakistan.
    Lal, Bhajan
    Shah Abdul Latif Univ, Pakistan.
    Nafady, Ayman
    King Saud Univ, Saudi Arabia.
    Ibupoto, Zafar Hussain
    Univ Sindh, Pakistan.
    Chemically Coupled Multiwall Carbon Nanotubes with Leaf-Like Nanostructures of NiO for Sensitive and Selective Determination of Uric Acid2021In: Journal of Electronic Materials, ISSN 0361-5235, E-ISSN 1543-186X, Vol. 50, no 5, p. 2852-2859Article in journal (Refereed)
    Abstract [en]

    The chemical coupling of NiO nanostructures with thermally treated multiwall carbon nanotubes (MWCNTs) is not reported as it provides an enhanced dispersion of composite material in water. The dispersion of MWCNTs has been considered a big challenge. For this purpose, we first thermally treated MWCNTs at 1000 degrees C in air for 30 min. Then, thermally treated MWCNTs were chemically coupled with NiO nanostructures by a hydrothermal method. The material characterization in terms of structure, morphology, and composition is well studied by different analytical techniques. The NiO composite (sample 2) with highest weight of MWCNTs had a leaf-like morphology and it exhibits a cubic phase of NiO. Cyclic voltammetry (CV) was used to study the electrochemical activity of prepared composite material towards the oxidation of uric acid in the phosphate buffer solution of pH 7.0. Sample 2 showed a well-behaved anodic peak with enhanced peak current and exhibited a linear range from 0.01 mM to 2.5 mM for uric acid with a low limit of detection 0.001mM. Sample 2 was found to be very selective under the environment of competing interferents such as urea, glucose, lactic acid and ethanol. This sample exhibits significant stability, thus it is a potential protocol for the monitoring of uric acid from real samples. This study provides a low-cost platform for the fabrication of efficient materials for various applications such as batteries, fuel cells and water splitting.

  • 16.
    Mugheri, Abdul Qayoom
    et al.
    Univ Sindh Jamshoro, Pakistan.
    Tahira, Aneela
    Linköping University, Department of Science and Technology, Physics, Electronics and Mathematics. Linköping University, Faculty of Science & Engineering.
    Aftab, Umair
    Mehran Univ Engn & Technol, Pakistan.
    Abro, Muhammad Ishaq
    Mehran Univ Engn & Technol, Pakistan.
    Bhatti, Adeel Liaquat
    Inst Phys Univ Sindh Jamshoro, Pakistan.
    Ali, Shahid
    Univ Baluchistan, Pakistan.
    Abbasi, Mazhar Ali
    Inst Phys Univ Sindh Jamshoro, Pakistan.
    Ibupoto, Zafar Hussain
    Univ Sindh Jamshoro, Pakistan.
    A Low Charge Transfer Resistance CuO Composite for Efficient Oxygen Evolution Reaction in Alkaline Media2021In: Journal of Nanoscience and Nanotechnology, ISSN 1533-4880, E-ISSN 1533-4899, Vol. 21, no 4, p. 2613-2620Article in journal (Refereed)
    Abstract [en]

    An efficient, simple, environment-friendly and inexpensive cupric oxide (CuO) electrocatalyst for oxygen evolution reaction (OER) is demonstrated. CuO is chemically deposited on the porous carbon material obtained from the dehydration of common sugar. The morphology of CuO on the porous carbon material is plate-like and monoclinic crystalline phase is confirmed by powder X-ray diffraction. The OER activity of CuO nanostructures is investigated in 1 M KOH aqueous solution. To date, the proposed electrocatalyst has the lowest possible potential of 1.49 V versus RHE (reversible hydrogen electrode) to achieve a current density of 20 mA/cm(2) among the. CuO based electrocatalysts and has Tafel slope of 115 mV dec(-1). The electrocatalyst exhibits an excellent long-term stability for 6 hours along with significant durability. The enhanced catalytic active centers of CuO on the carbon material are due to the porous structure of carbon as well as strong coupling between CuO-C. The functionalization of metal oxides or other related nanostructured materials on porous carbon obtained from common sugar provides an opportunity for the development of efficient energy conversion and energy storage systems.

  • 17.
    Mugheri, Abdul Qayoom
    et al.
    Univ Sindh Jamshoro, Pakistan.
    Tahira, Aneela
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Aftab, Umair
    Mehran Univ Engn and Technol, Pakistan.
    Abro, Muhammad Ishaq
    Mehran Univ Engn and Technol, Pakistan.
    Chaudhry, Saleem Raza
    Univ Engn and Technol, Pakistan.
    Amaral, Luis
    Univ Engn and Technol, Pakistan; Univ Lisbon, Portugal.
    Ibupoto, Zafar Hussain
    Univ Sindh Jamshoro, Pakistan.
    Facile efficient earth abundant NiO/C composite electrocatalyst for the oxygen evolution reaction Electronic supplementary information (ESI) available. See DOI: 10.1039/c8ra10472g2019In: RSC Advances, E-ISSN 2046-2069, Vol. 9, no 10, p. 5701-5710Article in journal (Refereed)
    Abstract [en]

    Due to the increasing energy consumption, designing efficient electrocatalysts for electrochemical water splitting is highly demanded. In this study, we provide a facile approach for the design and fabrication of efficient and stable electrocatalysts through wet chemical methods. The carbon material, obtained by the dehydration of sucrose sugar, provides high surface area for the deposition of NiO nanostructures and the resulting NiO/C catalysts show higher activity towards the OER in alkaline media. During the OER, a composite of NiO with 200 mg C can produce current densities of 10 and 20 mA cm(-2) at a bias of 1.45 V and 1.47 V vs. RHE, respectively. Electrochemical impedance spectroscopy experiments showed the lowest charge transfer resistance and the highest double layer capacitance in the case of the NiO/C composite with 200 mg C. The presence of C for the deposition of NiO nanostructures increases the active centers and consequently a robust electrocatalytic activity is achieved. The obtained results in terms of the low overpotential and small Tafel slope of 55 mV dec(-1) for non-precious catalysts are clear indications for the significant advancement in the field of electrocatalyst design for water splitting. This composite material based on NiO/C is simple and scalable for widespread use in various applications, especially in supercapacitors and lithium-ion batteries.

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  • 18.
    Mugheri, Abdul Qayoom
    et al.
    Univ Sindh Jamshoro, Pakistan.
    Tahira, Aneela
    Linköping University, Department of Science and Technology, Physics, Electronics and Mathematics. Linköping University, Faculty of Science & Engineering.
    Aftab, Umair
    Mehran Univ Engn and Technol, Pakistan.
    Abro, Muhammad Ishaq
    Mehran Univ Engn and Technol, Pakistan.
    Mallah, Arfana Begum
    Univ Sindh Jamshoro, Pakistan.
    Memon, Gulam Zuhra
    Univ Sindh Jamshoro, Pakistan.
    Khan, Humaira
    Univ Sindh Jamshoro, Pakistan.
    Abbasi, Mazhar Ali
    Univ Sindh, Pakistan.
    Halepoto, Imran Ali
    Univ Sindh, Pakistan.
    Chaudhry, Saleem Raza
    Univ Engn and Technol, Pakistan.
    Ibupoto, Zafar Hussain
    Univ Sindh Jamshoro, Pakistan.
    An advanced and efficient Co3O4/C nanocomposite for the oxygen evolution reaction in alkaline media2019In: RSC Advances, E-ISSN 2046-2069, RSC ADVANCES, Vol. 9, no 59, p. 34136-34143Article in journal (Refereed)
    Abstract [en]

    The design of efficient nonprecious catalysts for the hydrogen evolution reaction (HER) or the oxygen evolution reaction (OER) is a necessary, but very challenging task to uplift the water-based economy. In this study, we developed a facile approach to produce porous carbon from the dehydration of sucrose and use it for the preparation of nanocomposites with cobalt oxide (Co3O4). The nanocomposites were studied by the powder X-ray diffraction and scanning electron microscopy techniques, and they exhibited the cubic phase of cobalt oxide and porous structure of carbon. The nanocomposites showed significant OER activity in alkaline media, and the current densities of 10 and 20 mA cm(-2) could be obtained at 1.49 and 1.51 V versus reversible hydrogen electrode (RHE), respectively. The impedance study confirms favorable OER activity on the surface of the prepared nanocomposites. The nanocomposite is cost-effective and can be capitalized in various energy storage technologies.

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  • 19.
    Mugheri, Abdul Qayoom
    et al.
    Univ Sindh Jamshoro, Pakistan.
    Tahira, Aneela
    Linköping University, Department of Science and Technology, Physics, Electronics and Mathematics. Linköping University, Faculty of Science & Engineering.
    Aftab, Umair
    Mehran Univ Engn & Technol, Pakistan.
    Bhatti, Adeel Liaquat
    Univ Sindh Jamshoro, Pakistan.
    Lal, Ramesh
    Shah Abdul Latif Univ Khairpur Mirs, Pakistan.
    Bhatti, Muhammad Ali
    Univ Sindh Jamshoro, Pakistan.
    Memon, Ghulam Zuhra
    Univ Sindh Jamshoro, Pakistan.
    Mallah, Arfana Begum
    Univ Sindh Jamshoro, Pakistan.
    Abassi, Mazhar Ali
    Univ Sindh Jamshoro, Pakistan.
    Nafady, Ayman
    King Saud Univ, Saudi Arabia.
    Ibupoto, Zafar Hussain
    Univ Sindh Jamshoro, Pakistan.
    Chemically Coupled Cobalt Oxide Nanosheets Decorated onto the Surface of Multiwall Carbon Nanotubes for Favorable Oxygen Evolution Reaction2021In: Journal of Nanoscience and Nanotechnology, ISSN 1533-4880, E-ISSN 1533-4899, Vol. 21, no 4, p. 2660-2667Article in journal (Refereed)
    Abstract [en]

    Cobalt oxide has been widely investigated among potential transition metal oxides for the electrochemical energy conversion, storage, and water splitting. However, they have inherently low electronic conductivity and high corrosive nature in alkaline media. Herein, we propose a promising and facile approach to improve the conductivity and charge transport of cobalt oxide Co3O4 through chemical coupling with well-dispersed multiwall carbon nanotubes (MWCNTs) during hydrothermal treatment. The morphology of prepared composite material consisting of nanosheets which are anchored on the MWCNTs as confirmed by scanning electron microscopy (SEM). A cubic crystalline system is exhibited by the cobalt oxide as confirmed by the X-ray diffraction study. The Co, O, and C are the only elements present in the composite material. FTIR study has indicated the successful coupling of cobalt oxide with MWCNTs. The chemically coupled cobalt oxide onto the surface of MWCNTs composite is found highly active towards oxygen evolution reaction (OER) with a low onset potential 1.44 V versus RHE, low overpotential 262 mV at 10 mAcm(-2) and small Tafel slope 81 mV dec(-1). For continuous operation of 40 hours during durability test, no decay in activity was recorded. Electrochemical impedance study further revealed a low charge transfer resistance of 70.64 Ohms for the composite material during the electrochemical reaction and which strongly favored OER kinetics. This work provides a simple, low cost, and smartly designing electrocatalysts via hydrothermal reaction for the catalysis and energy storage applications.

  • 20.
    Mugheri, Abdul Qayoom
    et al.
    Univ Sindh, Pakistan.
    Tahira, Aneela
    Linköping University, Department of Science and Technology, Physics, Electronics and Mathematics. Linköping University, Faculty of Science & Engineering.
    Aftab, Umair
    Mehran Univ Engn and Technol, Pakistan.
    Bhatti, Adeel Liaquat
    Univ Sindh, Pakistan.
    Memon, Nusrat Naeem
    Univ Sindh, Pakistan.
    Memon, Jamil-ur-Rehman
    Univ Sindh, Pakistan.
    Abro, Muhammad Ishaque
    Mehran Univ Engn and Technol, Pakistan.
    Shah, Aqeel Ahmed
    NED Univ Engn Sci and Technol, Pakistan.
    Willander, Magnus
    Linköping University, Department of Science and Technology, Physics, Electronics and Mathematics. Linköping University, Faculty of Science & Engineering.
    Hullio, Ahmed Ali
    Univ Sindh, Pakistan.
    Ibupoto, Zafar Hussain
    Univ Sindh, Pakistan.
    Efficient tri-metallic oxides NiCo2O4/CuO for the oxygen evolution reaction2019In: RSC ADVANCES, Vol. 9, no 72, p. 42387-42394Article in journal (Refereed)
    Abstract [en]

    In this study, a simple approach was used to produce nonprecious, earth abundant, stable and environmentally friendly NiCo2O4/CuO composites for the oxygen evolution reaction (OER) in alkaline media. The nanocomposites were prepared by a low temperature aqueous chemical growth method. The morphology of the nanostructures was changed from nanowires to porous structures with the addition of CuO. The NiCo2O4/CuO composite was loaded onto a glassy carbon electrode by the drop casting method. The addition of CuO into NiCo2O4 led to reduction in the onset potential of the OER. Among the composites, 0.5 grams of CuO anchored with NiCo2O4 (sample 2) demonstrated a low onset potential of 1.46 V vs. a reversible hydrogen electrode (RHE). A current density of 10 mA cm(-2) was achieved at an over-potential of 230 mV and sample 2 was found to be durable for 35 hours in alkaline media. Electrochemical impedance spectroscopy (EIS) indicated a small charge transfer resistance of 77.46 ohms for sample 2, which further strengthened the OER polarization curves and indicates the favorable OER kinetics. All of the obtained results could encourage the application of sample 2 in water splitting batteries and other energy related applications.

  • 21.
    Mustafa, Elfatih Mohammed
    et al.
    Linköping University, Department of Science and Technology, Physics, Electronics and Mathematics. Linköping University, Faculty of Science & Engineering.
    Tahira, Aneela
    Linköping University, Department of Science and Technology, Physics, Electronics and Mathematics. Linköping University, Faculty of Science & Engineering.
    Elhadi Adam, Rania Elhadi
    Linköping University, Department of Science and Technology, Physics, Electronics and Mathematics. Linköping University, Faculty of Science & Engineering.
    Ibupoto, Zafar Hussain
    Univ Sindh, Pakistan.
    Elhag, Sami
    Linköping University, Department of Science and Technology, Physics, Electronics and Mathematics. Linköping University, Faculty of Science & Engineering.
    Willander, Magnus
    Linköping University, Department of Science and Technology, Physics, Electronics and Mathematics. Linköping University, Faculty of Science & Engineering.
    Nur, Omer
    Linköping University, Department of Science and Technology, Physics, Electronics and Mathematics. Linköping University, Faculty of Science & Engineering.
    Correction: Efficient Ni-Fe layered double hydroxides/ ZnO nanostructures for photochemical water splitting (vol 273, pg 186, 2019)2021In: Journal of Solid State Chemistry, ISSN 0022-4596, E-ISSN 1095-726X, Vol. 293, article id 121764Article in journal (Other academic)
    Abstract [en]

    n/a

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  • 22.
    Mustafa, Elfatih
    et al.
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Tahira, Aneela
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Adam, Rania Elhadi
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Ibupoto, Zafar Hussain
    Institute of Chemistry, University of Sindh, 76080, Jamshoro, Pakistan.
    Elhag, Sami
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Willander, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Nur, Omer
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Efficient Ni–Fe layered double hydroxides/ZnO nanostructures for photochemical water splitting2019In: Journal of Solid State Chemistry, ISSN 0022-4596, E-ISSN 1095-726X, Vol. 273, p. 186-191Article in journal (Refereed)
    Abstract [en]

    Zinc oxide (ZnO) nanostructures are widely investigated for photocatalytic applications but the functional properties are limited by the fast carrier recombination rate, which is an intrinsic property of ZnO. To optimize the recombination rate of ZnO, a study is carried out in which it is covered with Ni-Fe layered double hydroxides and synergistic effects are created which boosted the photocatalytic activity of ZnO. The nanostructured materials are synthesized by the low temperature aqueous chemical growth and electrodeposition methods. These nanostructures are characterized by scanning electron microscopy (SEM) and powder X-ray diffraction (XRD) technique. SEM study has revealed a Ni–Fe LDH coated ZnO NRs. The powder XRD has showed a cubic phase of the Ni-Fe layered double hydroxide on the ZnO NRs having an excellent crystalline quality. The optical characterization has shown low scattering of light for the Ni–Fe LDH coated ZnO NRs sample. The sample prepared with deposition time of 25 s showed excellent photochemical water splitting properties compared to counter photo-anodes in alkaline media. The photo response was highly stable and fast. The incident photon to current conversion efficiency for the photo-anode of Ni–Fe(LDHs)/ZnO over 25 s was 82% at a maximum absorption of 380 nm compared to the pristine ZnO NRs which has 70% at the same wavelength. This study is providing a simple, cost effective, earth abundant and environment friendly methodology for the fabrication of photo-anodes for diverse applications specifically water oxidation and solar radiation driven water splitting.

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  • 23.
    Qayoom Mugheri, Abdul
    et al.
    Univ Sindh Jamshoro, Pakistan.
    Tahira, Aneela
    Linköping University, Department of Science and Technology, Physics, Electronics and Mathematics. Linköping University, Faculty of Science & Engineering.
    Aftab, Umair
    Mehran Univ Engn and Technol, Pakistan.
    Ishaq Abro, Muhammad
    Mehran Univ Engn and Technol, Pakistan.
    Chaudhry, Saleem Raza
    Univ Engn and Technol, Pakistan.
    Amaral, Luis
    Univ Lisbon, Portugal.
    Ibupoto, Zafar Hussain
    Univ Sindh Jamshoro, Pakistan.
    Co3O4/ NiO bifunctional electrocatalyst for water splitting2019In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 306Article in journal (Refereed)
    Abstract [en]

    The development of noble metal free and active bifunctional catalysts for water splitting in alkaline media is highly demanded but very challenging. Herein, synergetic effects developed between two nonprecious metal oxides, Co3O4 and NiO, are reported, with the resulting composite showing promising properties as a catalyst for alkaline water electrolysis. The activity of the composite material towards both the HER and the OER was enhanced and the dynamic potential decreased, as compared with its counterparts. Importantly, low Tafel slopes of 101 and 61 mVdec(-1) are found for the composite catalyst for OER and HER respectively. EIS measurements revealed a decreased impedance response of the composite dominated by the intermediate frequency relaxation, related to the adsorption of intermediates. Moreover, based on the structural features the improved catalytic activity of the composite is also due to high electroactive surface area, swift electron transfer kinetics, and excellent electrical chemical coupling between Co3O4 and NiO. (c) 2019 Elsevier Ltd. All rights reserved.

  • 24.
    Shah, Aqeel Ahmed
    et al.
    NED Univ Engn & Technol Karachi, Pakistan.
    Bhatti, Muhammad Ali
    Univ Sindh Jamshoro, Pakistan.
    Chandio, Ali Dad
    NED Univ Engn & Technol Karachi, Pakistan.
    Almani, Khalida Faryal
    Univ Sindh Jamshoro, Pakistan.
    Abbasi, Mazhar Ali
    Univ Sindh Jamshoro, Pakistan.
    Bhatti, Adeel Liaquat
    Univ Sindh Jamshoro, Pakistan.
    Mugheri, Abdul Qayoom
    Univ Sindh Jamshoro, Pakistan.
    Willander, Magnus
    Linköping University, Department of Science and Technology, Physics, Electronics and Mathematics. Linköping University, Faculty of Science & Engineering.
    Nur, Omer
    Linköping University, Department of Science and Technology, Physics, Electronics and Mathematics. Linköping University, Faculty of Science & Engineering.
    Waryani, Baradi
    Univ Sindh Jamshoro, Pakistan.
    Tahira, Aneela
    Linköping University, Department of Science and Technology, Physics, Electronics and Mathematics. Linköping University, Faculty of Science & Engineering.
    Ibupoto, Zafar Hussain
    Univ Sindh Jamshoro, Pakistan.
    Tin as an Effective Doping Agent into ZnO for the Improved Photodegradation of Rhodamine B2021In: Journal of Nanoscience and Nanotechnology, ISSN 1533-4880, E-ISSN 1533-4899, Vol. 21, no 4, p. 2529-2537Article in journal (Refereed)
    Abstract [en]

    We have fabricated ZnO nano rods by hydrothermal method and successively doped them with tin (Sn) using different concentrations of 25, 50, 75 and 100 mg of tin chloride. XRD of the fabricated structures showed that ZnO possess hexagonal wurtzite phase. Scanning electron microscopy (SEM) was used to explore the morphology and it shows nanorod like morphology for all samples and no considerable change in the structural features were found. The dimension of nanorod is 200 to 300 nm. The doped materials were then investigated for their photo catalytic degradation of environmental pollutant Rhodamine B. The performance of doped ZnO is compared with the pristine ZnO. Scanning electron microscopy (SEM) was used to explore the morphology and it shows nanorod like morphology for all samples and no considerable change in the structural features were found. The dimension of nanorod is 200 to 300 nm. XRD of the fabricated structures showed that ZnO possess hexagonal wurtzite phase. Photo catalytic activity of rhodamine B was investigated under UV light and a maximum degradation efficiency of 85% was obtained. The optical property reveals the reduction in band gap of upto 17.14% for 100 mg Sn doped ZnO. The degradation is followed by the pseudo order kinetics. The produced results are unique in terms of facile synthesis of Sn doped ZnO and excellent photo degradation efficiency, therefore these materials can be used for other environmental applications.

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  • 25.
    Shah, Aqeel Ahmed
    et al.
    NED University of Engineering and Technology Karachi, Pakistan.
    Bhatti, Muhammad Ali
    University of Sindh Jamshoro, Sindh, Pakistan.
    Tahira, Aneela
    Linköping University, Department of Science and Technology, Physics, Electronics and Mathematics. Linköping University, Faculty of Science & Engineering.
    Chandio, Ali Dad
    NED University of Engineering and Technology Karachi, Pakistan.
    Channa, Iftikhar A.
    NED University of Engineering and Technology Karachi, Pakistan.
    Sahito, Ali Ghulam
    University of Sindh Jamshoro, Sindh, Pakistan.
    Chalangar, Ebrahim
    Linköping University, Department of Science and Technology, Physics, Electronics and Mathematics. Linköping University, Faculty of Science & Engineering.
    Willander, Magnus
    Linköping University, Faculty of Science & Engineering. Linköping University, Department of Science and Technology, Physics, Electronics and Mathematics.
    Nur, Omer
    Linköping University, Faculty of Science & Engineering. Linköping University, Department of Science and Technology, Physics, Electronics and Mathematics.
    Ibupoto, Zafar Hussain
    University of Sindh Jamshoro, Sindh, Pakistan.
    Facile synthesis of copper doped ZnO nanorods for the efficient photo degradation of methylene blue and methyl orange2020In: Ceramics International, ISSN 0272-8842, E-ISSN 1873-3956, ISSN 0272-8842, Vol. 46, no 8, p. 9997-10005Article in journal (Refereed)
    Abstract [en]

    In this study, zinc oxide (ZnO) nanorods are doped with copper by low temperature aqueous chemical growth method using different concentrations of copper 5 mg, 10 mg, 15 mg and 20 mg and labeled as sample 1, 2, 3 and 4 respectively. The morphology and phase purity of nanostructures was investigated by scanning electron microscopy, and powder X-ray diffraction techniques. The optical characterization was carried out through UV-Vis spectrophotometer. The band gap of coper doped ZnO has brought reduction at 250-600 nm and it indicates the fewer time for the recombination of electron and hole pairs, thus enhanced photo degradation efficiency is found. ZnO exhibits nanorods like shape even after the doping of copper. The photo degradation efficiency for the two chronic dyes such as methyl orange MO and methylene blue MB was found to be 57.5% and 60% respectively for a time of 180 mints. This study suggests that the copper impurity in ZnO can tailor its photocatalytic activity at considerable rate. The proposed photo catalysts are promising and can be used for the waste water treatment and other environmental applications.

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  • 26. Order onlineBuy this publication >>
    Tahira, Aneela
    Linköping University, Department of Science and Technology, Physics, Electronics and Mathematics. Linköping University, Faculty of Science & Engineering.
    Electrochemical water splitting based on metal oxide composite nanostructures2020Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The occurrence of available energy reservoirs is decreasing steeply, therefore we are looking for an alternative and sustainable renewable energy resources. Among them, hydrogen is considered as green fuel with a high density of energy. In nature, hydrogen is not found in a free state and it is most likely present in the compound form for example H2O. Water covers almost 75% of the earth planet. To produce hydrogen from water, it requires an efficient catalyst. For this purpose, noble materials such as Pt, Ir, and Ru are efficient materials for water splitting. These precious catalysts are rare in nature, very costly, and are restricted from largescale applications. Therefore, search for a new earth-abundant and nonprecious materials is a hot spot area in the research today. Among the materials, nanomaterials are excellent candidates because of their potential properties for extended applications, particularly in energy systems. The fabrication of nanostructured materials with high specific surface area, fast charge transport, rich catalytic sites, and huge ion transport is the key challenge for turning nonprecious materials into precious catalytic materials. In this thesis, we have investigated nonprecious nanostructured materials and they are found to be efficient for electrochemical water splitting. These nanostructured materials include MoS2-TiO2, MoS2, TiO2, MoSx@NiO, NiO, nickeliron layered double hydroxide (NiFeLDH)/Co3O4, NiFeLDH, Co3O4, Cu-doped MoS2, Co3O4- CuO, CuO, etc. The composition, morphology, crystalline structure, and phase purities are investigated by a wide range of analytical instruments such as XPS, SEM, HRTEM, and XRD. The production of hydrogen/oxygen from water is obtained either in the acidic or alkaline media. Based on the functional characterization we believe that these newly produced nanostructured materials can be capitalized for the development of water splitting, batteries, and other energy-related devices.

    List of papers
    1. Advanced Electrocatalysts for Hydrogen Evolution Reaction Based on Core-Shell MoS2/TiO2 Nanostructures in Acidic and Alkaline Media
    Open this publication in new window or tab >>Advanced Electrocatalysts for Hydrogen Evolution Reaction Based on Core-Shell MoS2/TiO2 Nanostructures in Acidic and Alkaline Media
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    2019 (English)In: ACS Applied Energy Materials, E-ISSN 2574-0962, Vol. 2, no 3, p. 2053-2062Article in journal (Refereed) Published
    Abstract [en]

    Hydrogen production as alternative energy source is still a challenge due to the lack of efficient and inexpensive catalysts, alternative to platinum. Thus, stable, earth abundant, and inexpensive catalysts are of prime need for hydrogen production via hydrogen evolution reaction (HER). Herein, we present an efficient and stable electrocatalyst composed of earth abundant TiO2 nanorods decorated with molybdenum disulfide thin nanosheets, a few nanometers thick. We grew rutile TiO2 nanorods via the hydrothermal method on conducting glass substrate, and then we nucleated the molybdenum disulfide nanosheets as the top layer. This composite possesses excellent hydrogen evolution activity in both acidic and alkaline media at considerably low overpotentials (350 mV and 700 mV in acidic and alkaline media, respectively) and small Tafel slopes (48 and 60 mV/dec in acidic and alkaline conditions, respectively), which are better than several transition metal dichalcogenides, such as pure molybdenum disulfide and cobalt diselenide. A good stability in acidic and alkaline media is reported here for the new MoS2/TiO2 electrocatalyst. These results demonstrate the potential of composite electrocatalysts for HER based on earth abundant, cost-effective, and environmentally friendly materials, which can also be of interest for a broader range of scalable applications in renewable energies, such as lithium sulfur batteries, solar cells, and fuel cells.

    Place, publisher, year, edition, pages
    AMER CHEMICAL SOC, 2019
    Keywords
    hydrogen evolution reaction; MoS2; TiO2; catalyst; acidic; alkaline
    National Category
    Other Chemical Engineering
    Identifiers
    urn:nbn:se:liu:diva-163971 (URN)10.1021/acsaem.8b02119 (DOI)000462944700053 ()
    Note

    Funding Agencies|Knut & Alice Wallenberg FoundationKnut & Alice Wallenberg Foundation [2016.0346]; Kempe Foundation [JCK-1606]; European Unions Horizon 2020 research and innovation programme [654002]

    Available from: 2020-03-05 Created: 2020-03-05 Last updated: 2020-12-15
    2. MoSx@NiO Composite Nanostructures: An Advanced Nonprecious Catalyst for Hydrogen Evolution Reaction in Alkaline Media
    Open this publication in new window or tab >>MoSx@NiO Composite Nanostructures: An Advanced Nonprecious Catalyst for Hydrogen Evolution Reaction in Alkaline Media
    Show others...
    2019 (English)In: Advanced Functional Materials, ISSN 1616-301X, E-ISSN 1616-3028, Vol. 29, no 7, article id 1807562Article in journal (Refereed) Published
    Abstract [en]

    The design of the earth-abundant, nonprecious, efficient, and stable electrocatalysts for efficient hydrogen evolution reaction (HER) in alkaline media is a hot research topic in the field of renewable energies. A heterostructured system composed of MoSx deposited on NiO nanostructures (MoSx@NiO) as a robust catalyst for water splitting is proposed here. NiO nanosponges are applied as cocatalyst for MoS2 in alkaline media. Both NiO and MoS2@NiO composites are prepared by a hydrothermal method. The NiO nanostructures exhibit sponge-like morphology and are completely covered by the sheet-like MoS2. The NiO and MoS2 exhibit cubic and hexagonal phases, respectively. In the MoSx@NiO composite, the HER experiment in 1 m KOH electrolyte results in a low overpotential (406 mV) to produce 10 mA cm(-2) current density. The Tafel slope for that case is 43 mV per decade, which is the lowest ever achieved for MoS2-based electrocatalyst in alkaline media. The catalyst is highly stable for at least 13 h, with no decrease in the current density. This simple, cost-effective, and environmentally friendly methodology can pave the way for exploitation of MoSx@NiO composite catalysts not only for water splitting, but also for other applications such as lithium ion batteries, and fuel cells.

    Place, publisher, year, edition, pages
    Wiley-VCH Verlagsgesellschaft, 2019
    Keywords
    alkaline media; electrolysis; MoSx@NiO composites
    National Category
    Materials Chemistry
    Identifiers
    urn:nbn:se:liu:diva-155574 (URN)10.1002/adfm.201807562 (DOI)000459719800018 ()2-s2.0-85059344786 (Scopus ID)
    Note

    Funding Agencies|Knut and Alice Wallenberg Foundation; Kempe Foundation; LTU Lab fund program; Generalitat de Catalunya [2017 SGR 327, JRM 2017 SGR 1246]; Spanish MINECO project [ENE2017-85087-C3]; Severo Ochoa Programme (MINECO) [SEV-2013-0295-17-1]; CERCA Programme/Generalitat de Catalunya

    Available from: 2019-03-20 Created: 2019-03-20 Last updated: 2020-05-14Bibliographically approved
    3. An efficient bifunctional electrocatalyst based on a nickel iron layered double hydroxide functionalized Co3O4 core shell structure in alkaline media
    Open this publication in new window or tab >>An efficient bifunctional electrocatalyst based on a nickel iron layered double hydroxide functionalized Co3O4 core shell structure in alkaline media
    Show others...
    2019 (English)In: Catalysis Science & Technology, ISSN 2044-4753, E-ISSN 2044-4761, Vol. 9, no 11, p. 2879-2887Article in journal (Refereed) Published
    Abstract [en]

    Developing highly active nonprecious metal and binder free bifunctional electrocatalysts for water splitting is a challenging task. In this study, we used a simple strategy to deposit a nickel iron layered double hydroxide (NiFeLDH) onto cobalt oxide (Co3O4) nanowires. The cobalt oxide nanowires are covered with thin nanosheets of NiFeLDH forming a core shell structure. The Co3O4 nanowires contain the mixed oxidation states of Co2+ and Co3+, and the surface modification of Co3O4 nanowires has shown synergetic effects due to there being more oxygen defects, catalytic sites, and enhanced electronic conductivity. Further, the core shell structure of Co3O4 nanowires demonstrated a bifunctional activity for water splitting in 1 M KOH aqueous solution. From the hydrogen evolution reaction (HER), a current density of 10 mA cm - 2 is achieved at a potential of - 0.303 V vs. reversible hydrogen electrode (RHE). Meanwhile for the case of the oxygen evolution reaction (OER), a current density of 40 mA cm - 2 is measured at a potential of 1.49 V vs. RHE. Also, this electrocatalyst has shown a considerable long- term stability of 15 h for both the HER and the OER. Importantly, electrochemical impedance spectroscopy has shown that the NiFeLDH integration onto cobalt oxide exhibited around 3 fold decrease of charge transfer resistance for both the HER and the OER in comparison with pristine cobalt oxide films, which reveals an excellent electrocatalytic activity for both faradaic processes. All these results confirm that the proposed electrocatalyst can be integrated into an efficient water splitting system.

    Place, publisher, year, edition, pages
    Royal Society of Chemistry, 2019
    National Category
    Materials Chemistry
    Identifiers
    urn:nbn:se:liu:diva-158546 (URN)10.1039/c9cy00351g (DOI)000470710300013 ()2-s2.0-85066976848 (Scopus ID)
    Available from: 2019-07-03 Created: 2019-07-03 Last updated: 2024-01-08Bibliographically approved
    4. Advanced Co3O4-CuO nano-composite based electrocatalyst for efficient hydrogen evolution reaction in alkaline media
    Open this publication in new window or tab >>Advanced Co3O4-CuO nano-composite based electrocatalyst for efficient hydrogen evolution reaction in alkaline media
    2019 (English)In: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 44, no 48, p. 26148-26157Article in journal (Refereed) Published
    Abstract [en]

    In this study, we incorporate a copper impurity into (Co3O4) nanowires precursor that turn them into an active catalyst for the hydrogen evolution reaction in 1M KOH. The XRD and XPS results are in good agreement and confirmed the formation of Co3O4-CuO nano composite by wet chemical method. To date, the performance of hydrogen evolution reaction in alkaline for the composite catalyst is comparable or superior to cobalt oxide based HER electro-catalysts. The HER catalyst exhibits the lowest Tafel slope of 65 mVdec(-1) for the cobalt-based catalysts in alkaline media. A current density of 10 mA/cm(2) is achieved at a potential of 0.288 V vs reversible hydrogen electrode (RHE). The mixed transition metal oxide Co3O4-CuO based HER electro-catalyst is highly stable and durable. The EIS results demonstrates that HER is highly favorable on the Co3O4-CuO due to the relatively small charge transfer resistance (173.20 Ohm) and higher capacitance values (1.97 mF). (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

    Place, publisher, year, edition, pages
    PERGAMON-ELSEVIER SCIENCE LTD, 2019
    Keywords
    Composite metal oxide; Electro-catalyst; Hydrogen evolution reaction
    National Category
    Other Chemical Engineering
    Identifiers
    urn:nbn:se:liu:diva-162348 (URN)10.1016/j.ijhydene.2019.08.120 (DOI)000494890900004 ()
    Available from: 2019-11-28 Created: 2019-11-28 Last updated: 2024-01-08
    5. The chemically reduced CuO-Co3O4 composite as a highly efficient electrocatalyst for oxygen evolution reaction in alkaline media
    Open this publication in new window or tab >>The chemically reduced CuO-Co3O4 composite as a highly efficient electrocatalyst for oxygen evolution reaction in alkaline media
    Show others...
    2019 (English)In: Catalysis Science & Technology, ISSN 2044-4753, E-ISSN 2044-4761, Vol. 9, no 22, p. 6274-6284Article in journal (Refereed) Published
    Abstract [en]

    The fabrication of efficient, alkaline-stable and nonprecious electrocatalysts for the oxygen evolution reaction is highly needed; however, it is a challenging task. Herein, we report a noble metal-free advanced catalyst, i.e. the chemically reduced mixed transition metal oxide CuO-Co3O4 composite, with outstanding oxygen evolution reaction activity in alkaline media. Sodium borohydride (NaBH4) was used as a reducing agent for the mixed transition metal oxide CuO-Co3O4. The chemically reduced composite carried mixed valence states of Cu and Co, which played a dynamic role in driving an excellent oxygen evolution reaction process. The X-ray photo-electron spectroscopy (XPS) study confirmed high density of active sites in the treated sample with a large number of oxygen vacancies. The developed electrocatalyst showed the lowest overpotential of 144.5 mV vs. the reversible hydrogen electrode (RHE) to achieve the current density of 40 mA cm(-2) and remained stable for 40 hours throughout the chronoamperometry test at the constant potential of 1.39 V vs. RHE. Moreover, the chemically reduced composite was highly durable. Electrochemical impedance spectroscopy (EIS) confirmed the low charge transfer resistance of 13.53 ohms for the chemically reduced composite, which was 50 and 26 times smaller than that of Co3O4 and untreated CuO-Co3O4, respectively. The electrochemically active surface area for the chemically reduced composite was found to be greater than that for pristine CuO, Co3O4 and untreated pristine CuO-Co3O4. These findings reveal the possibility of a new gateway for the capitalization of a chemically reduced sample into diverse energy storage and conversion systems such as lithium-ion batteries and supercapacitors.

    Place, publisher, year, edition, pages
    ROYAL SOC CHEMISTRY, 2019
    National Category
    Materials Chemistry
    Identifiers
    urn:nbn:se:liu:diva-162507 (URN)10.1039/c9cy01754b (DOI)000496465000004 ()
    Available from: 2019-12-13 Created: 2019-12-13 Last updated: 2024-01-08
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  • 27.
    Tahira, Aneela
    et al.
    Linköping University, Department of Science and Technology, Physics, Electronics and Mathematics. Linköping University, Faculty of Science & Engineering.
    Ibupoto, Zafar Hussain
    Univ Sindh, Pakistan.
    Nafady, Ayman
    King Saud Univ, Saudi Arabia.
    Willander, Magnus
    Linköping University, Department of Science and Technology, Physics, Electronics and Mathematics. Linköping University, Faculty of Science & Engineering.
    Nur, Omer
    Linköping University, Department of Science and Technology, Physics, Electronics and Mathematics. Linköping University, Faculty of Science & Engineering.
    Efficient and Stable Co3O4/ZnO Nanocomposite for Photochemical Water Splitting2022In: Journal of cluster science, ISSN 1040-7278, E-ISSN 1572-8862, Vol. 33, no 1, p. 387-394Article in journal (Refereed)
    Abstract [en]

    In this study, an efficient Co3O4/ZnO based composite was prepared by the low temperature aqueous chemical growth method for photoelectrochemical water splitting. Both ZnO and Co3O4 constituents are identified in the composite sample through X-ray diffraction technique. Scanning electron microscopy has shown the nanorod like morphology of ZnO with etched top surface. The energy dispersive spectroscopy has shown the presence of cobalt, oxygen and zinc as the main elements in the composite samples. The Co3O4/ZnO composite (with low content of cobalt chloride hexahydrate) shows a significant increase in the photocurrent density (3 mA/cm(2) at 0.5 V vs Ag/AgCl, which is 10 times higher than the pristine ZnO). Importantly, a fast and stable photocurrent response is found at an illumination of 1 Sun of light. The superior performance of the Co3O4/ZnO composite system is attributed to the facile promotion of electron-hole charge carrier separation and favourable charge transport. Furthermore, the electrochemical impedance spectroscopy showed a small charge transfer resistance of 259.30 Ohms for the composite material and consequently a robust water splitting is obtained. The prepared composite is earth abundant, inexpensive and scalable, therefore it can be used for diverse applications.

  • 28.
    Tahira, Aneela
    et al.
    Linköping University, Department of Science and Technology, Physics, Electronics and Mathematics. Linköping University, Faculty of Science & Engineering.
    Ibupoto, Zafar Hussain
    Univ Sindh Jamshoro, Pakistan.
    Vagin, Mikhail
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Science & Engineering.
    Aftab, Umair
    Mehran Univ Engn and Technol, Pakistan.
    Abro, Muhammad Ishaq
    Mehran Univ Engn and Technol, Pakistan.
    Willander, Magnus
    Linköping University, Department of Science and Technology, Physics, Electronics and Mathematics. Linköping University, Faculty of Science & Engineering.
    Nur, Omer
    Linköping University, Department of Science and Technology, Physics, Electronics and Mathematics. Linköping University, Faculty of Science & Engineering.
    An efficient bifunctional electrocatalyst based on a nickel iron layered double hydroxide functionalized Co3O4 core shell structure in alkaline media2019In: Catalysis Science & Technology, ISSN 2044-4753, E-ISSN 2044-4761, Vol. 9, no 11, p. 2879-2887Article in journal (Refereed)
    Abstract [en]

    Developing highly active nonprecious metal and binder free bifunctional electrocatalysts for water splitting is a challenging task. In this study, we used a simple strategy to deposit a nickel iron layered double hydroxide (NiFeLDH) onto cobalt oxide (Co3O4) nanowires. The cobalt oxide nanowires are covered with thin nanosheets of NiFeLDH forming a core shell structure. The Co3O4 nanowires contain the mixed oxidation states of Co2+ and Co3+, and the surface modification of Co3O4 nanowires has shown synergetic effects due to there being more oxygen defects, catalytic sites, and enhanced electronic conductivity. Further, the core shell structure of Co3O4 nanowires demonstrated a bifunctional activity for water splitting in 1 M KOH aqueous solution. From the hydrogen evolution reaction (HER), a current density of 10 mA cm - 2 is achieved at a potential of - 0.303 V vs. reversible hydrogen electrode (RHE). Meanwhile for the case of the oxygen evolution reaction (OER), a current density of 40 mA cm - 2 is measured at a potential of 1.49 V vs. RHE. Also, this electrocatalyst has shown a considerable long- term stability of 15 h for both the HER and the OER. Importantly, electrochemical impedance spectroscopy has shown that the NiFeLDH integration onto cobalt oxide exhibited around 3 fold decrease of charge transfer resistance for both the HER and the OER in comparison with pristine cobalt oxide films, which reveals an excellent electrocatalytic activity for both faradaic processes. All these results confirm that the proposed electrocatalyst can be integrated into an efficient water splitting system.

    Download full text (pdf)
    fulltext
  • 29.
    Tahira, Aneela
    et al.
    Linköping University, Department of Science and Technology, Physics, Electronics and Mathematics. Linköping University, Faculty of Science & Engineering.
    Ibupoto, Zafar Hussain
    Univ Sindh, Pakistan.
    Willander, Magnus
    Linköping University, Department of Science and Technology, Physics, Electronics and Mathematics. Linköping University, Faculty of Science & Engineering.
    Nur, Omer
    Linköping University, Department of Science and Technology, Physics, Electronics and Mathematics. Linköping University, Faculty of Science & Engineering.
    Advanced Co3O4-CuO nano-composite based electrocatalyst for efficient hydrogen evolution reaction in alkaline media2019In: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 44, no 48, p. 26148-26157Article in journal (Refereed)
    Abstract [en]

    In this study, we incorporate a copper impurity into (Co3O4) nanowires precursor that turn them into an active catalyst for the hydrogen evolution reaction in 1M KOH. The XRD and XPS results are in good agreement and confirmed the formation of Co3O4-CuO nano composite by wet chemical method. To date, the performance of hydrogen evolution reaction in alkaline for the composite catalyst is comparable or superior to cobalt oxide based HER electro-catalysts. The HER catalyst exhibits the lowest Tafel slope of 65 mVdec(-1) for the cobalt-based catalysts in alkaline media. A current density of 10 mA/cm(2) is achieved at a potential of 0.288 V vs reversible hydrogen electrode (RHE). The mixed transition metal oxide Co3O4-CuO based HER electro-catalyst is highly stable and durable. The EIS results demonstrates that HER is highly favorable on the Co3O4-CuO due to the relatively small charge transfer resistance (173.20 Ohm) and higher capacitance values (1.97 mF). (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

    Download full text (pdf)
    fulltext
  • 30.
    Ujan, Zaheer Ahmed
    et al.
    Univ Sindh Jamshoro, Pakistan.
    Tahira, Aneela
    Linköping University, Department of Science and Technology, Physics, Electronics and Mathematics. Linköping University, Faculty of Science & Engineering.
    Mahesar, Aftab Ahmed
    Mehran Univ Engn & Technol, Pakistan.
    Markhand, Akhter Hussain
    Univ Sindh Jamshoro, Pakistan.
    Bhatti, Adeel Liaquat
    Univ Sindh Jamshoro, Pakistan.
    Mugheri, Abdul Qayoom
    Univ Sindh Jamshoro, Pakistan.
    Bhatti, Muhammad Ali
    Univ Sindh Jamshoro, Pakistan.
    Shaikh, Nek Muhammad
    Univ Sindh Jamshoro, Pakistan.
    Mari, Riaz Hussain
    Univ Sindh Jamshoro, Pakistan.
    Nafady, Ayman
    King Saud Univ, Saudi Arabia.
    Ibupoto, Zafar Hussain
    Univ Sindh Jamshoro, Pakistan.
    The Crystal Disorder into ZnO with Addition of Bromine and Its Outperform Role in the Photodegradation of Methylene Blue2022In: Journal of cluster science, ISSN 1040-7278, E-ISSN 1572-8862, Vol. 33, no 1, p. 281-291Article in journal (Refereed)
    Abstract [en]

    In this research work, bromine (Br) is successfully doped into ZnO nanostructures using solvothermal method. The morphology, crystalline features, and composition of Br doped ZnO nanostructures were studied by scanning electron microscopy (SEM), X-ray diffraction (XRD) and energy dispersive X ray spectroscopy (EDX) respectively. These newly prepared nanostructured materials were tested as photocatalysts for the photodegradation of methylene blue (MB) in aqueous solution under UV light. The kinetic rate constants were observed in the order (20% Br/ZnO > 15% Br/ZnO > 10% Br/ZnO > 5% Br/ZnO >pristine ZnO), thus they are indicating that the increasing Br dopant level has linear effect on the photodegradation of MB. The photocatalytic degradation efficiency of 60% was achieved for the pristine ZnO during the irradiation of UV light for 5 h, however 20% Br doped ZnO nanostructures has shown enhanced degradation efficiency of 97.63% during the irradiation of UV light for short interval of time of 2.2 h. The 20% Br/ZnO describes the highest rate constant value of (24.13 x 10(-3) min(-1)), for time period of 2.2 h and this values is about 8 and 4 times higher than the pristine ZnO (3.72 x 10(-3) min(-1)) and 5% Br/ZnO (6.13 x 10(-3) min(-1)), respectively. The obtained results of 20% Br doped ZnO sample are superior or equal in performance than the recently reported works. The catalytic mechanism is also proposed and it indicates the role of electrons coming from the bromine ion might act as radical for the degradation of MB. The present approach is simpler, environment friendly, scalable and could be of great consideration for the diverse energy and environment related applications. Graphic

  • 31.
    Waryani, Baradi
    et al.
    Fisheries Univ Sindh, Pakistan.
    Tahira, Aneela
    Linköping University, Department of Science and Technology, Physics, Electronics and Mathematics. Linköping University, Faculty of Science & Engineering.
    Ameen, Sidra
    Univ Sindh, Pakistan.
    Willander, Magnus
    Linköping University, Department of Science and Technology, Physics, Electronics and Mathematics. Linköping University, Faculty of Science & Engineering.
    Abbasi, Abdul Rasool
    Fisheries Univ Sindh, Pakistan.
    Ibupoto, Zafar Hussain
    Univ Sindh, Pakistan.
    Correction: The Enzyme Free Uric Acid Sensor Based on Iron Doped CuO Nanostructures for the Determination of Uric Acid from Commercial Seafood (Oct, 10.1007/s11664-020-08345-x, 2020)2021In: Journal of Electronic Materials, ISSN 0361-5235, E-ISSN 1543-186X, Vol. 50, no 1, p. 397-397Article in journal (Other academic)
    Abstract [en]

    n/a

  • 32.
    Waryani, Baradi
    et al.
    Fisheries Univ Sindh, Pakistan.
    Tahira, Aneela
    Linköping University, Department of Science and Technology, Physics, Electronics and Mathematics. Linköping University, Faculty of Science & Engineering.
    Ameen, Sidra
    Univ Sindh, Pakistan.
    Willander, Magnus
    Linköping University, Department of Science and Technology, Physics, Electronics and Mathematics. Linköping University, Faculty of Science & Engineering.
    Abbasi, Abdul Rasool
    Fisheries Univ Sindh, Pakistan.
    Ibupoto, Zafar Hussain
    Univ Sindh, Pakistan.
    The Enzyme Free Uric Acid Sensor Based on Iron Doped CuO Nanostructures for the Determination of Uric Acid from Commercial Seafood2020In: Journal of Electronic Materials, ISSN 0361-5235, E-ISSN 1543-186X, Vol. 49, no 10, p. 6123-6129Article in journal (Refereed)
    Abstract [en]

    In this study, a wet chemical method was used to produce iron-doped CuO nanostructures. Cyclic voltammetry was employed to record sensor signals in a saline phosphate buffer solution of pH 7.3. Iron added into CuO nanostructures contributed electrons to the conduction band of CuO, showing a well-resolved electro-oxidation peak for uric acid. The developed sensor exhibits a wide linear range of uric acid concentrations from 0.05 mM to 4 mM. The limit of detection for the sensor was found to be 0.01 mM. The sensor is highly selective, sensitive, and stable. The results of the in vitro analysis of uric acid motivated the researchers to measure the uric acid from the marine shellfishPerna viridisand razor clamSolen dactylus. The obtained results reveal that the proposed sensor will help to avoid the gout and could be used as an early safeguard of human health.

1 - 32 of 32
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