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  • 1. Bestill onlineKjøp publikasjonen >>
    Adam, Rania Elhadi
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik, elektroteknik och matematik. Linköpings universitet, Tekniska fakulteten.
    Synthesis and Characterization of Some Nanostructured Materials for Visible Light-driven Photo Processes2020Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Nanostructured materials for visible light driven photo-processes such as photodegradation of organic pollutants and photoelectrochemical (PEC) water oxidation for hydrogen production are very attractive because of the positive impact on the environment. Metal oxides-based nanostructures are widely used in these photoprocesses due to their unique properties. But single nanostructured metal oxide material might suffer from low efficiency and instability in aqueous solutions under visible light. These facts make it important to have an efficient and reliable nanocomposite for the photo-processes. The combination of different nanomaterials to form a composite configuration can produce a material with new properties. The new properties which are due to the synergetic effect, are a combination of the properties of all the counterparts of the nanocomposite. Zinc oxides (ZnO) have unique optical and electrical properties which grant it to be used in optoelectronics, sensors, solar cells, nanogenerators, and photocatalysis activities. Although ZnO absorbs visible light from the sun due to the deep level band, it mainly absorbs ultraviolet wavelengths which constitute a small portion of the whole solar spectrum range. Also, ZnO has a problem with the high recombination rate of the photogenerated electrons. These problems might reduce its applicability to the photo-process. Therefore, our aim is to develop and investigate different nanocomposites materials based on the ZnO nanostructures for the enhancement of photocatalysis processes using the visible solar light as a green source of energy. Two photo-processes were applied to examine the developed nanocomposites through photocatalysis: (1) the photodegradation of organic dyes, (2) PEC water splitting. In the first photo-process, we used the ZnO nanoparticles (NPs), Magnesium (Mg)-doped ZnO NPs, and plasmonic ZnO/graphene-based nanocomposite for the decomposition of some organic dyes that have been used in industries. For the second photo-process, ZnO photoelectrode composite with different silver-based semiconductors to enhance the performance of the ZnO photoelectrode was used for PEC reaction analysis to perform water splitting. The characterization and photocatalysis experiment results showed remarkable enhancement in the photocatalysis efficiency of the synthesized nanocomposites. The observed improved properties of the ZnO are due to the synergetic effects are caused by the addition of the other nanomaterials. Hence, the present thesis attends to the synthesis and characterization of some nanostructured materials composite with ZnO that are promising candidates for visible light-driven photo-processes.  

    Delarbeid
    1. Synthesis of ZnO nanoparticles by co-precipitation method for solar driven photodegradation of Congo red dye at different pH
    Åpne denne publikasjonen i ny fane eller vindu >>Synthesis of ZnO nanoparticles by co-precipitation method for solar driven photodegradation of Congo red dye at different pH
    2018 (engelsk)Inngår i: PHOTONICS AND NANOSTRUCTURES-FUNDAMENTALS AND APPLICATIONS, ISSN 1569-4410, Vol. 32, s. 11-18Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    Solar driven photocatalytic processes to remove organic pollutants from wastewater and other aqueous solutions is very important and useful due to its environmental benefits regarding sustainability aspect. In this article, we report a study on the use of bare zinc oxide (ZnO) nanoparticles (NPs) prepared by the chemical low temperature co-precipitation method and used as a catalyst to degrade the Congo red dye from aqueous solution using solar radiation. We performed the photocatalytic experiments for degradation of Congo red dye under solar radiation at different pH values. The results showed that the ZnO NPs are effective under solar radiation for degradation of Congo red dye. Even when the pH was varied down to 4 or raised to 10, the degradation was observed to be slightly improved. This result is due to the excess of radicals species, which enhance the photocatalytic process. In general, the observed degradation efficiency of the ZnO NPs is due to the deep level defects within the band gap that were introduced during the growth process of the ZnO NPs, which enhance the absorption wavelength band towards the visible light region. Recycling of the ZnO NPs for 3 successive runs have indicated the feasibility of reusing the NPs for several times. This implies that by using bare ZnO NPs an efficient approach for degradation of toxic waste can be achieved. Radical scavengers were used to evaluate the role of the radicals in the reaction mechanism.

    sted, utgiver, år, opplag, sider
    ELSEVIER SCIENCE BV, 2018
    Emneord
    ZnO nanoparticles; Point defects; Photocatalytic
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-153525 (URN)10.1016/j.photonics.2018.08.005 (DOI)000451653700003 ()
    Merknad

    Funding Agencies|department of Science and Technology, Linkoping University, Sweden

    Tilgjengelig fra: 2018-12-20 Laget: 2018-12-20 Sist oppdatert: 2020-03-18
    2. Synthesis of Mg-doped ZnO NPs via a chemical low-temperature method and investigation of the efficient photocatalytic activity for the degradation of dyes under solar light
    Åpne denne publikasjonen i ny fane eller vindu >>Synthesis of Mg-doped ZnO NPs via a chemical low-temperature method and investigation of the efficient photocatalytic activity for the degradation of dyes under solar light
    Vise andre…
    2020 (engelsk)Inngår i: Solid State Sciences, ISSN 1293-2558, E-ISSN 1873-3085, Vol. 99, artikkel-id 106053Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    Doped semiconductors nanostructures (NSs) have shown great interest as a potential for green and efficient photocatalysis activities. Magnesium (Mg)-doped zinc oxide (ZnO) nanoparticles (NPs) has been synthesized by a one-step chemical low temperature (60 °C) co-precipitation method without further calcination and their photocatalytic performance for photodegradation of Methylene blue (MB) dye under the illumination of solar light is investigated. The crystal structure of the synthesized NPs is examined by X-ray diffraction (XRD). XRD data indicates a slight shift towards higher 2θ angle in Mg-doped samples as compared to the pure ZnO NPs which suggest the incorporation of Mg2+ into ZnO crystal lattice. X-ray photoelectron spectroscopy (XPS), UV–Vis spectrophotometer and cathodoluminescence (CL) spectroscopy, were used to study electronics, and optical properties, respectively. The XPS analysis confirms the substitution of the Zn2+ by the Mg2+ into the ZnO crystal lattice in agreement with the XRD data. The photocatalytic activities showed a significant enhancement of the Mg-doped ZnO NPs in comparison with pure ZnO NPs. Hole/radical scavengers were used to reveal the mechanism of the photodegradation. It was found that the addition of the Mg to the ZnO lattices increases the absorption of the hydroxyl ions at the surface of the NPs and hence acts as a trap site leading to decrease the electron-hole pair and consequently enhancing the photodegradation.

    sted, utgiver, år, opplag, sider
    Elsevier, 2020
    Emneord
    ZnO nanoparticles, Mg-doped ZnO NPs, Photocatalytic, Photodegradation, Methylene blue, Congo red
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-164333 (URN)10.1016/j.solidstatesciences.2019.106053 (DOI)000516720100024 ()2-s2.0-85074706430 (Scopus ID)
    Tilgjengelig fra: 2020-03-18 Laget: 2020-03-18 Sist oppdatert: 2020-03-24bibliografisk kontrollert
    3. Graphene-based plasmonic nanocomposites for highly enhanced solar-driven photocatalytic activities
    Åpne denne publikasjonen i ny fane eller vindu >>Graphene-based plasmonic nanocomposites for highly enhanced solar-driven photocatalytic activities
    Vise andre…
    2019 (engelsk)Inngår i: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 9, nr 52, s. 30585-30598Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    High-efficiency photocatalysts are crucial for the removal of organic pollutants and environmental sustainability. In the present work, we report on a new low-temperature hydrothermal chemical method, assisted by ultrasonication, to synthesize disruptive plasmonic ZnO/graphene/Ag/AgI nanocomposites for solar-driven photocatalysis. The plasmonic nanocomposites were investigated by a wide range of characterization techniques, confirming successful formation of photocatalysts with excellent degradation efficiency. Using Congo red as a model dye molecule, our experimental results demonstrated a photocatalytic reactivity exceeding 90% efficiency after one hour simulated solar irradiation. The significantly enhanced degradation efficiency is attributed to improved electronic properties of the nanocomposites by hybridization of the graphene and to the addition of Ag/AgI which generates a strong surface plasmon resonance effect in the metallic silver further improving the photocatalytic activity and stability under solar irradiation. Scavenger experiments suggest that superoxide and hydroxyl radicals are responsible for the photodegradation of Congo red. Our findings are important for the fundamental understanding of the photocatalytic mechanism of ZnO/graphene/Ag/AgI nanocomposites and can lead to further development of novel efficient photocatalyst materials.

    sted, utgiver, år, opplag, sider
    Royal Meteorological Society, 2019
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-160568 (URN)10.1039/C9RA06273D (DOI)000487989300064 ()
    Merknad

    Funding agencies: Department of Science and Technology (ITN) at Campus Norrkoping, Linkoping University, Sweden; Knut and Alice Wallenberg FoundationKnut & Alice Wallenberg Foundation

    Tilgjengelig fra: 2019-09-30 Laget: 2019-09-30 Sist oppdatert: 2020-03-18bibliografisk kontrollert
    4. n–n ZnO–Ag2CrO4 heterojunction photoelectrodes with enhanced visible-light photoelectrochemical properties
    Åpne denne publikasjonen i ny fane eller vindu >>n–n ZnO–Ag2CrO4 heterojunction photoelectrodes with enhanced visible-light photoelectrochemical properties
    Vise andre…
    2019 (engelsk)Inngår i: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 9, nr 14, s. 7992-8001Artikkel i tidsskrift (Fagfellevurdert) 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

    sted, utgiver, år, opplag, sider
    Royal Society of Chemistry, 2019
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-155657 (URN)10.1039/C9RA00639G (DOI)000462646000051 ()2-s2.0-85062919263 (Scopus ID)
    Merknad

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

    Tilgjengelig fra: 2019-03-22 Laget: 2019-03-22 Sist oppdatert: 2020-03-18bibliografisk kontrollert
    5. ZnO/Ag/Ag2WO4 photo-electrodes with plasmonic behavior for enhanced photoelectrochemical water oxidation
    Åpne denne publikasjonen i ny fane eller vindu >>ZnO/Ag/Ag2WO4 photo-electrodes with plasmonic behavior for enhanced photoelectrochemical water oxidation
    Vise andre…
    2019 (engelsk)Inngår i: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 9, nr 15, s. 8271-8279Artikkel i tidsskrift (Fagfellevurdert) 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

    sted, utgiver, år, opplag, sider
    Royal Society of Chemistry, 2019
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-155655 (URN)10.1039/C8RA10141H (DOI)000461445300016 ()
    Tilgjengelig fra: 2019-03-22 Laget: 2019-03-22 Sist oppdatert: 2020-03-18bibliografisk kontrollert
    Fulltekst (pdf)
    fulltext
    Download (png)
    presentationsbild
  • 2.
    Adam, Rania Elhadi
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik, elektroteknik och matematik. Linköpings universitet, Tekniska fakulteten.
    Alnoor, Hatim
    Linköpings universitet, Institutionen för teknik och naturvetenskap. Linköpings universitet, Tekniska fakulteten.
    Pozina, Galia
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Liu, Xianjie
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Laboratoriet för organisk elektronik. Linköpings universitet, Tekniska fakulteten.
    Willander, Magnus
    Linköpings universitet, Tekniska fakulteten. Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik, elektroteknik och matematik.
    Nur, Omer
    Linköpings universitet, Tekniska fakulteten. Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik, elektroteknik och matematik.
    Synthesis of Mg-doped ZnO NPs via a chemical low-temperature method and investigation of the efficient photocatalytic activity for the degradation of dyes under solar light2020Inngår i: Solid State Sciences, ISSN 1293-2558, E-ISSN 1873-3085, Vol. 99, artikkel-id 106053Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Doped semiconductors nanostructures (NSs) have shown great interest as a potential for green and efficient photocatalysis activities. Magnesium (Mg)-doped zinc oxide (ZnO) nanoparticles (NPs) has been synthesized by a one-step chemical low temperature (60 °C) co-precipitation method without further calcination and their photocatalytic performance for photodegradation of Methylene blue (MB) dye under the illumination of solar light is investigated. The crystal structure of the synthesized NPs is examined by X-ray diffraction (XRD). XRD data indicates a slight shift towards higher 2θ angle in Mg-doped samples as compared to the pure ZnO NPs which suggest the incorporation of Mg2+ into ZnO crystal lattice. X-ray photoelectron spectroscopy (XPS), UV–Vis spectrophotometer and cathodoluminescence (CL) spectroscopy, were used to study electronics, and optical properties, respectively. The XPS analysis confirms the substitution of the Zn2+ by the Mg2+ into the ZnO crystal lattice in agreement with the XRD data. The photocatalytic activities showed a significant enhancement of the Mg-doped ZnO NPs in comparison with pure ZnO NPs. Hole/radical scavengers were used to reveal the mechanism of the photodegradation. It was found that the addition of the Mg to the ZnO lattices increases the absorption of the hydroxyl ions at the surface of the NPs and hence acts as a trap site leading to decrease the electron-hole pair and consequently enhancing the photodegradation.

  • 3.
    Adam, Rania Elhadi
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik, elektroteknik och matematik. Linköpings universitet, Tekniska fakulteten.
    Chalangar, Ebrahim
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik, elektroteknik och matematik. Linköpings universitet, Tekniska fakulteten. School of Information Technology, Halmstad University, Halmstad, Sweden.
    Pirhashemi, Mahsa
    Department of Chemistry, Faculty of Sciences, University of Mohaghegh Ardabili, Ardabil, Iran.
    Pozina, Galia
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Liu, Xianjie
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Ytors Fysik och Kemi. Linköpings universitet, Tekniska fakulteten.
    Palisaitis, Justinas
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Pettersson, Håkan
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik, elektroteknik och matematik. Linköpings universitet, Tekniska fakulteten. School of Information Technology, Halmstad University, Halmstad, Sweden; Solid State Physics and NanoLund, Lund University, Lund, Sweden.
    Willander, Magnus
    Linköpings universitet, Tekniska fakulteten. Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik, elektroteknik och matematik.
    Nur, Omer
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik, elektroteknik och matematik. Linköpings universitet, Tekniska fakulteten.
    Graphene-based plasmonic nanocomposites for highly enhanced solar-driven photocatalytic activities2019Inngår i: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 9, nr 52, s. 30585-30598Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    High-efficiency photocatalysts are crucial for the removal of organic pollutants and environmental sustainability. In the present work, we report on a new low-temperature hydrothermal chemical method, assisted by ultrasonication, to synthesize disruptive plasmonic ZnO/graphene/Ag/AgI nanocomposites for solar-driven photocatalysis. The plasmonic nanocomposites were investigated by a wide range of characterization techniques, confirming successful formation of photocatalysts with excellent degradation efficiency. Using Congo red as a model dye molecule, our experimental results demonstrated a photocatalytic reactivity exceeding 90% efficiency after one hour simulated solar irradiation. The significantly enhanced degradation efficiency is attributed to improved electronic properties of the nanocomposites by hybridization of the graphene and to the addition of Ag/AgI which generates a strong surface plasmon resonance effect in the metallic silver further improving the photocatalytic activity and stability under solar irradiation. Scavenger experiments suggest that superoxide and hydroxyl radicals are responsible for the photodegradation of Congo red. Our findings are important for the fundamental understanding of the photocatalytic mechanism of ZnO/graphene/Ag/AgI nanocomposites and can lead to further development of novel efficient photocatalyst materials.

    Fulltekst (pdf)
    fulltext
  • 4.
    Elhadi Adam, Rania Elhadi
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik, elektroteknik och matematik. Linköpings universitet, Tekniska fakulteten.
    Alnoor, Hatim
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Pozina, Galia
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Liu, Xianjie
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Ytors Fysik och Kemi. Linköpings universitet, Tekniska fakulteten.
    Willander, Magnus
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik, elektroteknik och matematik. Linköpings universitet, Tekniska fakulteten.
    Nur, Omer
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik, elektroteknik och matematik. Linköpings universitet, Tekniska fakulteten.
    Synthesis of Mg-doped ZnO NPs via a chemical low-temperature method and investigation of the efficient photocatalytic activity for the degradation of dyes under solar light2020Inngår i: Solid State Sciences, ISSN 1293-2558, E-ISSN 1873-3085, Vol. 99, artikkel-id 106053Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Doped semiconductors nanostructures (NSs) have shown great interest as a potential for green and efficient photocatalysis activities. Magnesium (Mg)-doped zinc oxide (ZnO) nanoparticles (NPs) has been synthesized by a one-step chemical low temperature (60 degrees C) co-precipitation method without further calcination and their photocatalytic performance for photodegradation of Methylene blue (MB) dye under the illumination of solar light is investigated. The crystal structure of the synthesized NPs is examined by X-ray diffraction (XRD). XRD data indicates a slight shift towards higher 2 theta angle in Mg-doped samples as compared to the pure ZnO NPs which suggest the incorporation of Mg2+ into ZnO crystal lattice. X-ray photoelectron spectroscopy (XPS), UV-Vis spectrophotometer and cathodoluminescence (CL) spectroscopy, were used to study electronics, and optical properties, respectively. The XPS analysis confirms the substitution of the Zn2+ by the Mg2+ into the ZnO crystal lattice in agreement with the XRD data. The photocatalytic activities showed a significant enhancement of the Mg-doped ZnO NPs in comparison with pure ZnO NPs. Hole/radical scavengers were used to reveal the mechanism of the photodegradation. It was found that the addition of the Mg to the ZnO lattices increases the absorption of the hydroxyl ions at the surface of the NPs and hence acts as a trap site leading to decrease the electron-hole pair and consequently enhancing the photodegradation.

  • 5.
    Elhadi Adam, Rania Elhadi
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap. Linköpings universitet, Tekniska fakulteten.
    Pozina, Galia
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Willander, Magnus
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska fakulteten.
    Nur, Omer
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska fakulteten.
    Synthesis of ZnO nanoparticles by co-precipitation method for solar driven photodegradation of Congo red dye at different pH2018Inngår i: PHOTONICS AND NANOSTRUCTURES-FUNDAMENTALS AND APPLICATIONS, ISSN 1569-4410, Vol. 32, s. 11-18Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Solar driven photocatalytic processes to remove organic pollutants from wastewater and other aqueous solutions is very important and useful due to its environmental benefits regarding sustainability aspect. In this article, we report a study on the use of bare zinc oxide (ZnO) nanoparticles (NPs) prepared by the chemical low temperature co-precipitation method and used as a catalyst to degrade the Congo red dye from aqueous solution using solar radiation. We performed the photocatalytic experiments for degradation of Congo red dye under solar radiation at different pH values. The results showed that the ZnO NPs are effective under solar radiation for degradation of Congo red dye. Even when the pH was varied down to 4 or raised to 10, the degradation was observed to be slightly improved. This result is due to the excess of radicals species, which enhance the photocatalytic process. In general, the observed degradation efficiency of the ZnO NPs is due to the deep level defects within the band gap that were introduced during the growth process of the ZnO NPs, which enhance the absorption wavelength band towards the visible light region. Recycling of the ZnO NPs for 3 successive runs have indicated the feasibility of reusing the NPs for several times. This implies that by using bare ZnO NPs an efficient approach for degradation of toxic waste can be achieved. Radical scavengers were used to evaluate the role of the radicals in the reaction mechanism.

  • 6.
    Elhadi Adam, Rania
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap. Linköpings universitet, Tekniska fakulteten.
    Mustafa, Elfatih
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska fakulteten.
    Elhag, Sami
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska fakulteten.
    Nur, Omer
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska fakulteten.
    Willander, Magnus
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska fakulteten.
    Photocatalytic properties for different metal-oxide nanomaterials2019Inngår i: Oxide-based Materials and Devices X, SPIE , 2019, artikkel-id 1091925Konferansepaper (Fagfellevurdert)
    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.

    Fulltekst (pdf)
    fulltext
  • 7.
    Elhadi Adam, Rania
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap. Linköpings universitet, Tekniska fakulteten.
    Pirhashemi, Mahsa
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska fakulteten. University of Mohaghegh Ardabili, Ardabil, Iran.
    Elhag, Sami
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska fakulteten.
    Liu, Xianjie
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Ytors Fysik och Kemi. Linköpings universitet, Tekniska fakulteten.
    Habibi-Yangjeh, Aziz
    University of Mohaghegh Ardabili, Ardabil, Iran.
    Willander, Magnus
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska fakulteten.
    Nur, Omer
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska fakulteten.
    ZnO/Ag/Ag2WO4 photo-electrodes with plasmonic behavior for enhanced photoelectrochemical water oxidation2019Inngår i: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 9, nr 15, s. 8271-8279Artikkel i tidsskrift (Fagfellevurdert)
    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

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  • 8.
    Mohammed, Rania Elhadi Adam
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap. Linköpings universitet, Tekniska fakulteten.
    Alnoor, Hatim
    Linköpings universitet, Institutionen för teknik och naturvetenskap. Linköpings universitet, Tekniska fakulteten.
    Elhag, Sami
    Linköpings universitet, Institutionen för teknik och naturvetenskap. Linköpings universitet, Tekniska fakulteten.
    Nur, Omer
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska fakulteten.
    Willander, Magnus
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska fakulteten.
    Zinc oxide nanostructures and its nano-compounds for efficient visible light photo-catalytic processes2017Inngår i: OXIDE-BASED MATERIALS AND DEVICES VIII, SPIE - International Society for Optical Engineering, 2017, Vol. 10105, artikkel-id UNSP 101050XKonferansepaper (Fagfellevurdert)
    Abstract [en]

    Zinc oxide (ZnO) in its nanostructure form is a promising material for visible light emission/absorption and utilization in different energy efficient photocatalytic processes. We will first present our recent results on the effect of varying the molar ratio of the synthesis nutrients on visible light emission. Further we will use the optimized conditions from the molar ration experiments to vary the synthesis processing parameters like stirring time etc. and the effect of all these parameters in order to optimize the efficiency and control the emission spectrum are investigated using different complementary techniques. Cathodoluminescence (CL) is combined with photoluminescence (PL) and electroluminescence (EL) as the techniques to investigate and optimizes visible light emission from ZnO/GaN light emitting diodes. We will then show and discuss our recent finding of the use of high quality ZnO nanoparticles (NPs) for efficient photo-degradation of toxic dyes using the visible spectra, namely with a wavelength up to 800 nm. In the end, we show how ZnO nanorods (NRs) are used as the first template to be transferred to bismuth zinc vanadate (BiZn2VO6). The BiZn2VO6 is then used to demonstrate efficient and cost effective hydrogen production through photo-electrochemical water splitting using solar radiation.

  • 9.
    Mustafa, Elfatih
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska fakulteten.
    Tahira, Aneela
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska fakulteten.
    Adam, Rania Elhadi
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska fakulteten.
    Ibupoto, Zafar Hussain
    Institute of Chemistry, University of Sindh, 76080, Jamshoro, Pakistan.
    Elhag, Sami
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska fakulteten.
    Willander, Magnus
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska fakulteten.
    Nur, Omer
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska fakulteten.
    Efficient Ni–Fe layered double hydroxides/ZnO nanostructures for photochemical water splitting2019Inngår i: Journal of Solid State Chemistry, ISSN 0022-4596, E-ISSN 1095-726X, Vol. 273, s. 186-191Artikkel i tidsskrift (Fagfellevurdert)
    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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    fulltext
  • 10.
    Pirhashemi, Mahsa
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska fakulteten. University of Mohaghegh Ardabili, Iran.
    Elhag, Sami
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska fakulteten.
    Elhadi Adam, Rania
    Linköpings universitet, Institutionen för teknik och naturvetenskap. Linköpings universitet, Tekniska fakulteten.
    Habibi-Yangjeh, Aziz
    University of Mohaghegh Ardabili, Iran.
    Liu, Xianjie
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Ytors Fysik och Kemi. Linköpings universitet, Tekniska fakulteten.
    Willander, Magnus
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska fakulteten.
    Nur, Omer
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska fakulteten.
    n–n ZnO–Ag2CrO4 heterojunction photoelectrodes with enhanced visible-light photoelectrochemical properties2019Inngår i: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 9, nr 14, s. 7992-8001Artikkel i tidsskrift (Fagfellevurdert)
    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

    Fulltekst (pdf)
    fulltext
  • 11.
    Savoyant, A.
    et al.
    Aix Marseille Univ, France.
    Rollo, M.
    Aix Marseille Univ, France.
    Texier, M.
    Aix Marseille Univ, France.
    Elhadi Adam, Rania Elhadi
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik, elektroteknik och matematik. Linköpings universitet, Tekniska fakulteten.
    Bernardini, S.
    Aix Marseille Univ, France.
    Pilone, O.
    Aix Marseille Univ, France.
    Margeat, O.
    Aix Marseille Univ, France.
    Nur, Omer
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik, elektroteknik och matematik. Linköpings universitet, Tekniska fakulteten.
    Willander, Magnus
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik, elektroteknik och matematik. Linköpings universitet, Tekniska fakulteten.
    Bertaina, S.
    Aix Marseille Univ, France.
    Light-induced high-spin state in ZnO nanoparticles2020Inngår i: Nanotechnology, ISSN 0957-4484, E-ISSN 1361-6528, Vol. 31, nr 9, artikkel-id 095707Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The effects of white-light irradiation on similar to 15.nm diameter ZnO nanoparticles are investigated by means of electron paramagnetic resonance, near liquid-nitrogen and liquid-helium temperatures. Under dark conditions, usual core- and surface-defects are detected, respectively, at g = 1.960 and g = 2.003. Under white-light illumination, the core-defect signal intensity is strongly increased, which is to be correlated to the light-induced conductivitys augmentation. Beside, a four-lines structure appears, with the same gravity center as that of the surface defects. Simulations and intensity power-dependence measurements show that this four-line-structure is very likely to arise from a localized high spin S = 2, induced by light irradiation, and subjected to a weak axial anisotropy. At 85K, this high-spin state can last several hours after the light-irradiation removal, probably due to highly spin-forbidden recombination process. The possible excited resonant complexes at the origin of this signal are discussed. Other light-induced S = 1/2-like centers are detected as well, which depend on the nanoparticles growth conditions.

    Fulltekst tilgjengelig fra 2020-12-10 06:00
  • 12.
    Willander, Magnus
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska fakulteten.
    Alnoor, Hatim
    Linköpings universitet, Institutionen för teknik och naturvetenskap. Linköpings universitet, Tekniska fakulteten.
    Savoyant, A.
    Aix Marseille Univ, France.
    Elhadi Adam, Rania Elhadi
    Linköpings universitet, Institutionen för teknik och naturvetenskap. Linköpings universitet, Tekniska fakulteten.
    Nur, Omer
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska fakulteten.
    Optical and magneto-optical properties of zinc-oxide nanostructures grown by the low-temperature chemical route2018Inngår i: OXIDE-BASED MATERIALS AND DEVICES IX, SPIE-INT SOC OPTICAL ENGINEERING , 2018, Vol. 10533, artikkel-id UNSP 105331DKonferansepaper (Fagfellevurdert)
    Abstract [en]

    We demonstrate that the low temperature synthesis chemical route can be utilized to control the functionality of zinc oxide (ZnO) nanoparticles (NPs) and nanorods (NRs) for optical and magneto-optical performance. Different structural, optical, electro-and magneto-optical results will be displayed and analyzed. In the first part, we show how high quality ZnO NPs can be efficient for photodegradation using ultra-violet radiation. In the second part we will present our recent results on the control of the core defects in cobalt doped ZnO NR. Here and by using electron paramagnetic resonance (EPR) measurements, the substitution of Co2+ ions in the ZnO NRs crystal is shown. The relation between the incorporation and core defects concentration will be discussed. The findings give access to the magnetic anisotropy of ZnO NRs grown by the low temperature chemical route and can lead to demonstrate room temperature ferromagnetism in nanostructures with potential for different device applications.

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