| 1. |
- Chalangar, Ebrahim, PhD student, 1984-, et al.
(author)
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Nanopatterned rGO/ZnO : Al seed layer for vertical growth of single ZnO nanorods
- 2023
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In: Nanotechnology. - Bristol : Institute of Physics Publishing (IOPP). - 0957-4484 .- 1361-6528. ; 34:25, s. 1-7
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Journal article (peer-reviewed)abstract
- In this work, we demonstrate a novel low-cost template-assisted route to synthesize vertical ZnO nanorod arrays on Si (100). The nanorods were grown on a patterned double seed layer comprised of reduced graphene oxide (rGO) and Al-doped ZnO nanoparticles. The seed layer was fabricated by spray-coating the substrate with graphene and then dip-coating it into a Al-doped ZnO sol-gel solution. The growth template was fabricated from a double-layer resist, spin-coated on top of the rGO/ZnO:Al seed layer, and patterned by colloidal lithography. The results show a successful chemical bath deposition of vertically aligned ZnO nanorods with controllable diameter and density in the nanoholes in the patterned resist mask. Our novel method can presumably be used to fabricate electronic devices on virtually any smooth substrate with a thermal budget of 1 min at 300 °C with the seed layer acting as a conductive strain-relieving back contact. The top contact can simply be made by depositing a suitable transparent conductive oxide or metal, depending on the specific application. © 2023 The Author(s). Published by IOP Publishing Ltd.
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| 2. |
- Dawi, E. A., et al.
(author)
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Ag/AgCl Decorated Ionic Liquid@Tantalum Pentoxide Nanostructures: Fabrication, Photocatalytic Activity, and Cytotoxicity Effects Against Human Brain Tumor Cells
- 2023
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In: JOURNAL OF INORGANIC AND ORGANOMETALLIC POLYMERS AND MATERIALS. - : SPRINGER. - 1574-1443. ; 33, s. 2647-2660
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Journal article (peer-reviewed)abstract
- Environmental contaminants have become a major concern for human beings due to their adverse effects on drinking water quality. Heterogeneous photocatalysis has been extensively investigated as a potential strategy to minimize the consequences of as-related processes. Using a room-temperature ionic liquid-mediated co-precipitation method, Ag@AgCl nanoparticles were loaded onto tantalum pentoxide to make a plasmonic photocatalyst to remove Congo Red dye. The physicochemical properties of the photocatalysts were characterized by X-ray diffraction powder (XRD), Scanning Electron Microscopy (SEM), Energy Dispersive X-ray (EDX), Diffuse Reflectance Spectroscopy (DRS), Fourier-transform infrared spectroscopy (FTIR), Transmission Electron Microscopy (TEM), photoluminescence (PL), and nitrogen adsorption-desorption isotherms. The results indicate that 96% of the dye was degraded within 20 min with a rate constant of 0.14 min(-1). The key radicals involved in the photocatalysis, recognized as O-2(center dot-) species, were identified by electron spin resonance (ESR) in the presence of 5,5-dimethyl-1-pyrroline-N-oxide (DMPO), as the spin trapping agent. Our findings and quenching experiments elucidates the mechanism of the charge carrier migration. The cytotoxicity activity of the nanostructures was also examined against human brain glioblastoma tumor cells for the first time. A precise analysis of the cell death pathway was conducted using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT), mitochondrial membrane potential (MMP), reactive oxygen species (ROS), and caspase activity assays in combination with fluorescence microscopy images. The prepared nanomaterials were found to be promising candidates for treating the organic pollutants and biomedical waste effluents from academic and industrial activities.
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| 3. |
- Mangrio, Sanjha, et al.
(author)
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Advanced Urea Precursors Driven NiCo2O4 Nanostructures Based Non-Enzymatic Urea Sensor for Milk and Urine Real Sample Applications
- 2023
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In: Biosensors. - : MDPI. - 2079-6374. ; 13:4
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Journal article (peer-reviewed)abstract
- The electrochemical performance of NiCo2O4 with urea precursors was evaluated in order to develop a non-enzymatic urea sensor. In this study, NiCo2O4 nanostructures were synthesized hydrothermally at different concentrations of urea and characterized using scanning electron microscopy and X-ray diffraction. Nanostructures of NiCo2O4 exhibit a nanorod-like morphology and a cubic phase crystal structure. Urea can be detected with high sensitivity through NiCo2O4 nanostructures driven by urea precursors under alkaline conditions. A low limit of detection of 0.05 and an analytical range of 0.1 mM to 10 mM urea are provided. The concentration of 006 mM was determined by cyclic voltammetry. Chronoamperometry was used to determine the linear range in the range of 0.1 mM to 8 mM. Several analytical parameters were assessed, including selectivity, stability, and repeatability. NiCo2O4 nanostructures can also be used to detect urea in various biological samples in a practical manner.
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| 4. |
- Mustafa, Elfatih Mohammed, 1977-
(author)
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Composite Nanostructured Materials for Renewable Energy Applications
- 2023
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Doctoral thesis (other academic/artistic)abstract
- Diverse sources of energy are becoming increasingly significant in today's world. The most common source of energy today is fossil fuels, such as coal, oil, and gas. While this energy source has many advantages, it also comes with many problems. In order to meet this demand, environmentally friendly and sustainable alternatives to energy are urgently needed. Renewable energy such as hydro, wind, photovoltaics, biomass, and geothermal is an attractive and promising kind of energy. Solar energy is among the most efficient, cleanest, and cheapest sources of energy. In this thesis, two photo-processes are utilized to produce solar energy using nanostructured materials. One is photocatalysis, mainly photoelectrochemical (PEC) water splitting for hydrogen production and photodegradation of organic dyes, and another is a sunlight-powered photovoltaic cell. In this thesis, we aim to demonstrate optimized low-cost sustainable electrodes based on nanostructured materials for solar energy applications. For PEC water splitting two materials namely ZnO NRs and CuO NLs are fabricated by hydrothermal methods followed by deposition of different materials such as Ag2WO4 and AgBr. These materials show relatively high PEC water splitting efficiency using sunlight. Similarly, for the photodegradation of organic dyes Ta2O5 is used with the addition of Ag/AgCl nanoparticles (Ag/AgCl NPs), which results in an effective plasmonic photocatalyst for the removal of water-soluble Congo red (CR) dye compounds. For high-efficiency solar cells two methods are applied. Firstly, a FDTD simulation method was applied to study the plasmon enhancement of light absorption from p-i-n junction GaAs nanowires. Secondly a study of anisotropic deformation of colloidal particles exposed to heavy ions irradiation. Finally, a novel low-cost template-assisted method was used in order to improve the alignment of ZnO NRs grown on Si substrates.
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| 5. |
- Mustafa, Elfatih Mohammed, et al.
(author)
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Efficient CuO/Ag2WO4 photoelectrodes for photoelectrochemical water splitting using solar visible radiation
- 2023
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In: RSC Advances. - : ROYAL SOC CHEMISTRY. - 2046-2069. ; 13:17, s. 11297-11310
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Journal article (peer-reviewed)abstract
- Water splitting energy production relies heavily on the development of high-performance photoelectrochemical cells (PECs). Among the most highly regarded semiconductor materials, cupric oxide (CuO) is an excellent photocathode material. Pristine CuO does not perform well as a photocathode due to its tendency to recombine electrons and holes rapidly. Photocathodes with high efficiency can be produced by developing CuO-based composite systems. The aim of our research is to develop an Ag2WO4/CuO composite by incorporating silver tungstate (Ag2WO4) nanoparticles onto hydrothermally grown CuO nanoleaves (NLs) by successive ionic layer adsorption and reaction (SILAR). To prepare CuO/Ag2WO4 composites, SILAR was used in conjunction with different Ag2WO4 nanoparticle deposition cycles. Physicochemical characterization reveals well-defined nanoleaves morphologies with tailored surface compositions. Composite CuO/Ag2WO4 crystal structures are governed by the monoclinic phase of CuO and the hexagonal phase of Ag2WO4. It has been demonstrated that the CuO/Ag2WO4 composite has outstanding performance in the PEC water splitting process when used with five cycles. In the CuO/Ag2WO4 photocathode, water splitting activity is observed at low overpotential and high photocurrent density, indicating that the reaction takes place at low energy barriers. Several factors contribute to PEC performance in composites. These factors include the high density of surface active sites, the high charge separation rate, the presence of favourable surface defects, and the synergy of CuO and Ag2WO4 photoreaction. By using SILAR, silver tungstate can be deposited onto semiconducting materials with strong visible absorption, enabling the development of energy-efficient photocathodes.
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| 6. |
- Solangi, Muhammad Yameen, et al.
(author)
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In-situ growth of nonstoichiometric CrO0.87 and Co3O4 hybrid system for the enhanced electrocatalytic water splitting in alkaline media
- 2023
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In: International journal of hydrogen energy. - : PERGAMON-ELSEVIER SCIENCE LTD. - 0360-3199 .- 1879-3487. ; 48:93, s. 36439-36451
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Journal article (peer-reviewed)abstract
- The development of electrocatalysts for electrochemical water splitting has received considerable attention in response to the growing demand for renewable energy sources and environmental concerns. In this study, a simple hydrothermal growth approach was developed for the in-situ growth of non-stoichiometric CrO0.87 and Co3O4 hybrid materials. It is apparent that the morphology of the prepared material shows a heterogeneous aggregate of irregularly shaped nanoparticles. Both CrO0.87 and Co3O4 have cubic crystal structures. Its chemical composition was governed by the presence of Co, Cr, and O as its main constituents. For understanding the role CrO0.87 plays in the half-cell oxygen evolu-tion reaction (OER) in alkaline conditions, CrO0.87 was optimized into Co3O4 nanostructures. The hybrid material with the highest concentration of CrO0.87 was found to be highly efficient at driving OER reactions at 255 mV and 20 mA cm(-2). The optimized material demonstrated excellent durability for 45 h and a Tafel slope of 56 mV dec(-1). Several factors may explain the outstanding performance of CrO0.87 and Co3O4 hybrid materials, including multiple metallic oxidation states, tailored surface properties, fast charge transport, and surface defects. An alternative method is proposed for the preparation of new generations of electrocatalysts for the conversion and storage of energy. (c) 2023 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.
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