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Elhag, Sami
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Publications (10 of 15) Show all publications
Mustafa, E., Tahira, A., Adam, R. E., Ibupoto, Z. H., Elhag, S., Willander, M. & Nur, O. (2019). Efficient Ni–Fe layered double hydroxides/ZnO nanostructures for photochemical water splitting. Journal of Solid State Chemistry, 273, 186-191
Open this publication in new window or tab >>Efficient Ni–Fe layered double hydroxides/ZnO nanostructures for photochemical water splitting
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2019 (English)In: Journal of Solid State Chemistry, ISSN 0022-4596, E-ISSN 1095-726X, Vol. 273, p. 186-191Article in journal (Refereed) Published
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.

Place, publisher, year, edition, pages
Academic Press, 2019
Keywords
ZnO nanorods, Ni–Fe layered double hydroxides, Photochemical water splitting
National Category
Physical Sciences
Identifiers
urn:nbn:se:liu:diva-155658 (URN)10.1016/j.jssc.2019.03.004 (DOI)000466261100027 ()2-s2.0-85062437722 (Scopus ID)
Note

Funding agencies:  department of Science and Technology, Campus Norrkoping, Linkoping University, Sweden

Available from: 2019-03-22 Created: 2019-03-22 Last updated: 2019-06-22Bibliographically approved
Pirhashemi, M., Elhag, S., Elhadi Adam, R., Habibi-Yangjeh, A., Liu, X., Willander, M. & Nur, O. (2019). n–n ZnO–Ag2CrO4 heterojunction photoelectrodes with enhanced visible-light photoelectrochemical properties. RSC Advances, 9(14), 7992-8001
Open this publication in new window or tab >>n–n ZnO–Ag2CrO4 heterojunction photoelectrodes with enhanced visible-light photoelectrochemical properties
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2019 (English)In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 9, no 14, p. 7992-8001Article in journal (Refereed) Published
Abstract [en]

In this study, ZnO nanorods (NRs) were hydrothermally grown on an Au-coated glass substrate at a relatively low temperature (90 °C), followed by the deposition of Ag2CrO4 particles via a successive ionic layer adsorption and reaction (SILAR) route. The content of the Ag2CrO4 particles on ZnO NRs was controlled by changing the number of SILAR cycles. The fabricated ZnO–Ag2CrO4 heterojunction photoelectrodes were subjected to morphological, structural, compositional, and optical property analyses; their photoelectrochemical (PEC) properties were investigated under simulated solar light illumination. The photocurrent responses confirmed that the ability of the ZnO–Ag2CrO4 heterojunction photoelectrodes to separate the photo-generated electron–hole pairs is stronger than that of bare ZnO NRs. Impressively, the maximum photocurrent density of about 2.51 mA cm−2 at 1.23 V (vs. Ag/AgCl) was measured for the prepared ZnO–Ag2CrO4 photoelectrode with 8 SILAR cycles (denoted as ZnO–Ag2CrO4-8), which exhibited about 3-fold photo-enhancement in the current density as compared to bare ZnO NRs (0.87 mA cm−2) under similar conditions. The improvement in photoactivity was attributed to the ideal band gap and high absorption coefficient of the Ag2CrO4 particles, which resulted in improved solar light absorption properties. Furthermore, an appropriate annealing treatment was proven to be an efficient process to increase the crystallinity of Ag2CrO4 particles deposited on ZnO NRs, which improved the charge transport characteristics of the ZnO–Ag2CrO4-8 photoelectrode annealed at 200 °C and increased the performance of the photoelectrode. The results achieved in the present work present new insights for designing n–n heterojunction photoelectrodes for efficient and cost-effective PEC applications and solar-to-fuel energ

Place, publisher, year, edition, pages
Royal Society of Chemistry, 2019
National Category
Physical Sciences
Identifiers
urn:nbn:se:liu:diva-155657 (URN)10.1039/C9RA00639G (DOI)000462646000051 ()2-s2.0-85062919263 (Scopus ID)
Note

Funding agencies: University of Mohaghegh Ardabili-Iran and Linkoping University-Sweden; AForsk [17-457

Available from: 2019-03-22 Created: 2019-03-22 Last updated: 2019-04-18Bibliographically approved
Elhadi Adam, R., Mustafa, E., Elhag, S., Nur, O. & Willander, M. (2019). Photocatalytic properties for different metal-oxide nanomaterials. In: Oxide-based Materials and Devices X: . Paper presented at SPIE OPTO, February 2-7 2019, San Francisco, California, United States. SPIE, Article ID 1091925.
Open this publication in new window or tab >>Photocatalytic properties for different metal-oxide nanomaterials
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2019 (English)In: Oxide-based Materials and Devices X, SPIE , 2019, article id 1091925Conference paper, Published paper (Refereed)
Abstract [en]

We here demonstrate the synthesis of different nanostructures, including nanoparticles, nanorods, core-shell structures,and compound metal oxide nanostructures all synthesized by a low temperature chemical process. We furtherinvestigated their photocatalytic properties for degradation of toxic waste and their photochemical efficiency for watersplitting. All the photocatalytic properties as well as the photochemical properties were utilized using sun radiation. Theresults presented indicate huge potential for the investigated processes with positive impact to energy consumption andbenefits for the environment.

Place, publisher, year, edition, pages
SPIE, 2019
Series
Proceedings of SPIE, ISSN 0277-786X, E-ISSN 1996-756X ; 10919
National Category
Physical Sciences
Identifiers
urn:nbn:se:liu:diva-155664 (URN)10.1117/12.2517436 (DOI)000485015600006 ()
Conference
SPIE OPTO, February 2-7 2019, San Francisco, California, United States
Note

Funding agencies: Knut and Alice Wallenberg foundation (KAW), through a Wallenberg Scholar grant; China Scholarship CouncilChina Scholarship Council

Available from: 2019-03-22 Created: 2019-03-22 Last updated: 2019-09-30
Elhadi Adam, R., Pirhashemi, M., Elhag, S., Liu, X., Habibi-Yangjeh, A., Willander, M. & Nur, O. (2019). ZnO/Ag/Ag2WO4 photo-electrodes with plasmonic behavior for enhanced photoelectrochemical water oxidation. RSC Advances, 9(15), 8271-8279
Open this publication in new window or tab >>ZnO/Ag/Ag2WO4 photo-electrodes with plasmonic behavior for enhanced photoelectrochemical water oxidation
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2019 (English)In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 9, no 15, p. 8271-8279Article in journal (Refereed) Published
Abstract [en]

Ag-based compounds are excellent co-catalyst that can enhance harvesting visible light and increase photo-generated charge carrier separation owing to its surface plasmon resonance (SPR) effect in photoelectrochemical (PEC) applications. However, the PEC performance of a ZnO/Ag/Ag2WO4 heterostructure with SPR behavior has not been fully studied so far. Here we report the preparation of a ZnO/Ag/Ag2WO4 photo-electrode with SPR behavior by a low temperature hydrothermal chemical growth method followed by a successive ionic layer adsorption and reaction (SILAR) method. The properties of the prepared samples were investigated by different characterization techniques, which confirm that Ag/Ag2WO4 was deposited on the ZnO NRs. The Ag2WO4/Ag/ZnO photo-electrode showed an enhancement in PEC performance compared to bare ZnO NRs. The observed enhancement is attributed to the red shift of the optical absorption spectrum of the Ag2WO4/Ag/ZnO to the visible region (>400 nm) and to the SPR effect of surface metallic silver (Ag0) particles from the Ag/Ag2WO4 that could generate electron–hole pairs under illumination of low energy visible sun light. Finally, we proposed the PEC mechanism of the Ag2WO4/Ag/ZnO photo-electrode with an energy band structure and possible electron–hole separation and transportation in the ZnO/Ag/Ag2WO4 heterostructure with SPR effect for water oxidation. ER

Place, publisher, year, edition, pages
Royal Society of Chemistry, 2019
National Category
Physical Sciences
Identifiers
urn:nbn:se:liu:diva-155655 (URN)10.1039/C8RA10141H (DOI)000461445300016 ()
Available from: 2019-03-22 Created: 2019-03-22 Last updated: 2019-04-08Bibliographically approved
Elhag, S., Khun, K., Khranovskyy, V., Liu, X., Willander, M. & Nour, O. (2016). Efficient Donor Impurities in ZnO Nanorods by Polyethylene Glycol for Enhanced Optical and Glutamate Sensing Properties. Sensors, 16(2)
Open this publication in new window or tab >>Efficient Donor Impurities in ZnO Nanorods by Polyethylene Glycol for Enhanced Optical and Glutamate Sensing Properties
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2016 (English)In: Sensors, ISSN 1424-8220, E-ISSN 1424-8220, Vol. 16, no 2Article in journal (Refereed) Published
Abstract [en]

In this paper, we show that the possibility of using polyethylene glycol (EG) as a hydrogen source and it is used to assist the hydrothermal synthesis of ZnO nanorods (ZNRs). EG doping in ZNRs has been found to significantly improve their optical and chemical sensing characteristics toward glutamate. The EG was found to have no role on the structural properties of the ZNRs. However, the x-ray photoelectron spectroscopy (XPS) suggests that the EG could induce donor impurities effect in ZnO. Photoluminescence (PL) and UV-Vis. spectra demonstrated this doping effect. Mott-Schottky analysis at the ZNRs/electrolyte interface was used to investigate the charge density for the doped ZNRs and showed comparable dependence on the used amount of EG. Moreover, the doped ZNRs were used in potentiometric measurements for glutamate for a range from 10(-6) M to 10(-3) M and the potential response of the sensor electrode was linear with a slope of 91.15 mV/decade. The wide range and high sensitivity of the modified ZNRs based glutamate biosensor is attributed to the doping effect on the ZNRs that is dictated by the EG along with the high surface area-to-volume ratio. The findings in the present study suggest new avenues to control the growth of n-ZnO nanostructures and enhance the performance of their sensing devices.

Place, publisher, year, edition, pages
MDPI AG, 2016
Keywords
potentiometric sensor; ZnO nanorods; glutamate; doping
National Category
Electrical Engineering, Electronic Engineering, Information Engineering Chemical Sciences Physical Sciences
Identifiers
urn:nbn:se:liu:diva-126849 (URN)10.3390/s16020222 (DOI)000371787800096 ()26861342 (PubMedID)
Note

Funding Agencies|University of Kordofan, El-Obeid, Kordofan Sudan [700]

Available from: 2016-04-05 Created: 2016-04-05 Last updated: 2017-11-30
Elhag, S., Ibupoto, Z. H., Khranovskyy, V., Willander, M. & Nour, O. (2015). Habit-modifying additives and their morphological consequences on photoluminescence and glucose sensing properties of ZnO nanostructures, grown via aqueous chemical synthesis. Vacuum, 116, 21-26
Open this publication in new window or tab >>Habit-modifying additives and their morphological consequences on photoluminescence and glucose sensing properties of ZnO nanostructures, grown via aqueous chemical synthesis
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2015 (English)In: Vacuum, ISSN 0042-207X, E-ISSN 1879-2715, Vol. 116, p. 21-26Article in journal (Refereed) Published
Abstract [en]

Generally, the anisotropic shape of inorganic nano-crystal can be influenced by one or more of different parameters i.e. kinetic energy barrier, temperature, time, and the nature of the capping molecules. Here, different surfactants acting as capping molecules were used to assist the aqueous chemical growth of zinc oxide (ZnO) nanostructures on Au coated glass substrates. The morphology, crystal quality and the photoluminescence (PL) properties of the ZnO nanostructures were investigated. The PL properties of the prepared ZnO nanostructures at room temperature showed a dominant UV luminescence peak, while the "green yellow" emissions were essentially suppressed. Moreover, the ZnO nanostructures were investigated for the development of a glucose biosensor. An adsorbed molecule has direct contribution on the glucose oxidase/ZnO/Au sensing properties. We show that the performance of a ZnO-based biosensor can be improved by tailoring the properties of the ZnO biomolecule interface through engineering of the morphology, effective surface area, and adsorption capability.

Place, publisher, year, edition, pages
Elsevier, 2015
Keywords
ZnO nanostructures; Cationic and anionic molecules; PL spectra; Glucose sensitivity
National Category
Physical Chemistry
Identifiers
urn:nbn:se:liu:diva-119245 (URN)10.1016/j.vacuum.2015.02.026 (DOI)000354582900004 ()
Note

Funding Agencies|University of Kordofan Grant, El-Obeid, Kordofan Sudan [700]

Available from: 2015-06-15 Created: 2015-06-12 Last updated: 2017-12-04
Khun, K., Elhag, S., Ibupoto, Z. H., Khranovskyy, V., Nur, O. & Willander, M. (2015). Supramolecules-assisted ZnO nanostructures growth and their UV photodetector application. Solid State Sciences, 41, 14-18
Open this publication in new window or tab >>Supramolecules-assisted ZnO nanostructures growth and their UV photodetector application
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2015 (English)In: Solid State Sciences, ISSN 1293-2558, E-ISSN 1873-3085, Vol. 41, p. 14-18Article in journal (Refereed) Published
Abstract [en]

Zinc oxide (ZnO) nanosheets, nickel oxide (NiO) nanoflowers and their nanocomposite were grown on the fluorine doped tin oxide (FTO) substrate. The supramolecules-assisted ZnO growth by a hydrothermal method used to tune the morphology of the grown ZnO nanostructures to nanosheets morphology. The synthesis, purity and the optical properties of the grown material were characterized by scanning electron microscopy (SEM), x-ray diffraction (XRD), UV-visible spectrometry and photoluminescence (PL) analysis. The current-voltage (I-V) characterization of the ZnO/NiO heterojunction was performed at room temperature and showed an obvious nonlinear and rectifying response. A strong UV absorption with fast switching was observed from the ZnO/NiO composite heterojunction. The proposed UV photodetector based on this nano-composite is more stable, possesses fast rising and decaying time response approximately 100 ms and low leakage current was investigated. The findings indicate that the importance of the use of controlled nanostructures morphology for developing efficient nanodevices for various applications

Place, publisher, year, edition, pages
Elsevier, 2015
Keywords
ZnO/NiO nano-composite; UV absorption ZnO; nano-heterojunction; UV photodetector
National Category
Physical Sciences Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:liu:diva-112863 (URN)10.1016/j.solidstatesciences.2015.01.011 (DOI)000350888800003 ()
Note

On the day of the defence date the status of this article was Manuscript.

Available from: 2014-12-18 Created: 2014-12-18 Last updated: 2017-12-05Bibliographically approved
Elhag, S., Hussain Ibupoto, Z., Nur, O. & Willander, M. (2015). Synthesis of Co3O4 Cotton-Like Nanostructures for Cholesterol Biosensor. Materials, 8(1), 149-161
Open this publication in new window or tab >>Synthesis of Co3O4 Cotton-Like Nanostructures for Cholesterol Biosensor
2015 (English)In: Materials, ISSN 1996-1944, E-ISSN 1996-1944, Vol. 8, no 1, p. 149-161Article in journal (Refereed) Published
Abstract [en]

The use of templates to assist and possess a control over the synthesis of nanomaterials has been an attractive option to achieve this goal. Here we have used sodium dodecyl sulfate (SDS) to act as a template for the low temperature synthesis of cobalt oxide (Co3O4) nanostructures. The use of SDS has led to tune the morphology, and the product was in the form of "cotton-like" nanostructures instead of connected nanowires. Moreover, the variation of the amount of the SDS used was found to affect the charge transfer process in the Co3O4. Using Co3O4 synthesized using the SDS for sensing of cholesterol was investigated. The use of the Co3O4 synthesized using the SDS was found to yield an improved cholesterol biosensor compared to Co3O4 synthesized without the SDS. The improvement of the cholesterol sensing properties upon using the SDS as a template was manifested in increasing the sensitivity and the dynamic range of detection. The results achieved in this study indicate the potential of using template assisted synthesis of nanomaterials in improving some properties, e. g., cholesterol sensing.

Place, publisher, year, edition, pages
MDPI, 2015
Keywords
C3O4 nanostructures; surfactant; hydrothermal synthesis; potentiometric processes; cholesterol biosensor
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:liu:diva-114594 (URN)10.3390/ma8010149 (DOI)000348403400010 ()
Available from: 2015-02-27 Created: 2015-02-26 Last updated: 2017-12-04
Elhag, S., Ibupoto, Z. H., Liu, X., Nur, O. & Willander, M. (2014). Dopamine wide range detection sensor based on modified Co3O4 nanowires electrode. Sensors and actuators. B, Chemical, 203, 543-549
Open this publication in new window or tab >>Dopamine wide range detection sensor based on modified Co3O4 nanowires electrode
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2014 (English)In: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 203, p. 543-549Article in journal (Refereed) Published
Abstract [en]

Ultra-thin cobalt oxide (Co3O4) nanowires grown on gold coated glass substrates by the hydrothermal chemical deposition and have been used as a wide range dopamine potentiometric sensor. An anionic surfactant ( sodium dodecylbenzenesulfonate) was used to achieve assisted growth procedure. Moreover, a polymeric membrane containing polyvinyl chloride as plasticized polymer, p-cyclodextrin as ionophore, and potassium tetrakis (4-chlorophenyl) borate as ionic additive were immobilized on the Co3O4 nanostructures through electrostatic adsorption method. X-ray diffraction, X-ray photoelectron spectroscopy, and scanning electron microscopy were used to characterize the electrodes while ultraviolet-visible absorption was used to investigate the band gap of the Co3O4 nanostructures. The structural characterization showed a cubic crystalline, pure phase, and nanowires morphology of the Co3O4. However, the morphology is altered when the surfactant concentration has been changed. The Co3O4 chemical modified electrodes were used in potentiometric measurements for dopamine in a 10(-2) M acetic acid/sodium acetate solution having a pH of 5.45. For dopamine range from 10(-9) M to 10(-2) M, the potential response of the sensor electrode was linear with a slope of 52 mV/decade. The wide range and high sensitivity of the modified Co3O4 nanowires based sensor for dopamine is attributed to the defects on the metal oxide that is dictated by the used surfactant along with the high surface area-to-volume ratio.

Place, publisher, year, edition, pages
Elsevier, 2014
Keywords
Potentiometric sensor; Chemically modified electrode; Surfactant; Dopamine chemical sensor
National Category
Electrical Engineering, Electronic Engineering, Information Engineering Physical Sciences
Identifiers
urn:nbn:se:liu:diva-111254 (URN)10.1016/j.snb.2014.07.028 (DOI)000341455400072 ()
Available from: 2014-10-15 Created: 2014-10-14 Last updated: 2017-12-05Bibliographically approved
Ibupoto, Z. H., Elhag, S., AlSalhi, M. S., Nur, O. & Willander, M. (2014). Effect of Urea on the Morphology of Co3O4 Nanostructures and Their Application for Potentiometric Glucose Biosensor. Electroanalysis, 26(8), 1773-1781
Open this publication in new window or tab >>Effect of Urea on the Morphology of Co3O4 Nanostructures and Their Application for Potentiometric Glucose Biosensor
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2014 (English)In: Electroanalysis, ISSN 1040-0397, E-ISSN 1521-4109, Vol. 26, no 8, p. 1773-1781Article in journal (Refereed) Published
Abstract [en]

In this study, an effect of different concentrations of urea on the morphology of cobalt oxide (Co3O4) nanostructures was investigated. The Co3O4 nanostructures are fabricated on gold coated glass substrate by the hydrothermal method. The morphological and structural characterization was performed by scanning electron microscopy, and X-ray diffraction techniques. The Co3O4 nanostructures exhibit morphology of flowers-like and have comprised on nanowires due to the increasing amount of urea. The nanostructures were highly dense on the substrate and possess a good crystalline quality. The Co3O4 nanostructures were successfully used for the development of a sensitive glucose biosensor. The presented glucose biosensor detected a wide range of glucose concentrations from 1 x 10(-6) M to 1 x 10(-2) M with sensitivity of a -56.85 mV/decade and indicated a fast response time of less than 10 s. This performance could be attributed to the heterogeneous catalysis effect at glucose oxidase enzyme, nanoflowers, and nanowires interfaces, which have enhanced the electron transfer process on the electrode surface. Moreover, the reproducibility, repeatability, stability and selectivity were also investigated. All the obtained results indicate the potential use of the developed glucose sensor for monitoring of glucose concentrations at drugs, human serum and food industry related samples.

Place, publisher, year, edition, pages
Wiley-VCH Verlagsgesellschaft, 2014
Keywords
Nanostructures; Hydrothermal method; Glucose biosensor
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:liu:diva-110486 (URN)10.1002/elan.201400116 (DOI)000340557700016 ()
Available from: 2014-09-15 Created: 2014-09-12 Last updated: 2017-12-05Bibliographically approved
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