Abdullah M. Al-Mayouf

Cooperative Catalytic Effect of ZrO2 and α‐Fe2O3 Nanoparticles on BiVO4 Photoanodes for Enhanced Photoelectrochemical Water Splitting

Photoelectrochemical water splitting with metal oxide semiconductors offers a cost-competitive alternative for the generation of solar fuels. Most of the materials studied so far suffer from poor charge-transfer kinetics at the semiconductor/liquid interface, making compulsory the use of catalytic layers to overcome the large overpotentials required for the water oxidation reaction. Herein, we report a very soft electrolytic synthesis deposition method, which allows remarkably enhanced water oxidation kinetics of BiVO4 photoanodes by the sequential addition of Zr and Fe precursors. Upon a heat treatment cycle, these precursors are converted into monoclinic ZrO2 and α-Fe2 O3 nanoparticles, which mainly act as catalysts, leading to a five-fold increase of the water oxidation photocurrent of BiVO4 . This method provides a versatile platform that is easy to apply to different semiconductor materials, fully reproducible, and facile to scale-up on large area conductive substrates with attractive implications for technological deployment.

A sensitive electrochemical detection of hydroquinone using newly synthesized α-Fe2O3-graphene oxide nanocomposite as an electrode material

This article presents the effect of hematite phase iron oxide (α-Fe2O3) on the electrocatalytic activity of graphene oxide (GO) for electrochemical detection of hydroquinone in aqueous solution. The different weight percentage (wt%) (1, 2 and 3%) of α-Fe2O3 added GO nanocomposites were synthesized by wet-impregnation method. The cyclic voltammetry studies using 2% α-Fe2O3-GO modified glassy carbon electrodes was found to exhibit an excellent electrocatalytic activity than α-Fe2O3 and GO electrodes that may be due to the synergistic effect of α-Fe2O3nanoparicles and GO sheet. In addition, the modified electrode exhibited a good reproducibility as well as long-term stability. Hence, the 2% α-Fe2O3-GO can be a promising catalytic material for electrochemical sensor applications.

Dissolution of Magnetite Coupled with Iron of Various Surface Areas

Abstract The effect of the galvanic coupling between magnetite and iron on their dissolution was investigated in aqueous solutions containing ethylenediaminetetraacetic acid (EDTA) in the presence ...

Synthesis, characterization, multifunctional electrochemical (OGR/ORR/SCs) and photodegradable activities of ZnWO 4 nanobricks

AbstractBrick-shaped zinc tungstate nanoparticles have been synthesized by ecofriendly solvent-free process using molten salts. Zinc tungstate nanobricks (ZnWO4 Nbs) were characterized by powder x-ray diffraction (PXRD), FTIR, Raman, energy dispersive and electron microscopic studies. ZnWO4 Nbs are used as the multifunctional electrode materials to oxygen generation reactions (OGR), oxygen reduction reactions (ORR) and supercapacitors (SCs) as well as photo-catalysts in the waste-water treatment by the degradation of organic dyes. Low overpotential (ƞ10 = 0.475 V), low tafel slope (140 mV/dec), high current density (~70 mA/cm2) and good stability of the electrodes are the key results of the present studies for water electrolysis (OGR/ORR). ZnWO4 Nbs have also shown great interest in supercapacitors with efficient charge–discharge activities in 1 M KOH. The specific capacitance and energy density of ZnWO4 Nbs were found to be 250 F/g and 80 Wh/kg, respectively, at 5 mV/s, these values are relatively higher than that of previously reported specific capacitance and energy density value of metal tungstate nanoparticles. ZnWO4 Nbs as the photo-catalysts work very significantly for photocatalytic degradation of aqueous MB dye solution (~85 % in 3 h) in neutral medium. ZnWO4 Nanobricks show significant multifunctional electro-chemical activities in alkaline medium and photocatalytic degradation of organic dye in neutral medium.HighlightsEcofriendly solvent-free Synthesis of ZnWO4 Nanobricks (Nbs).ZnWO4 Nbs show admirable multifunctional electrochemical activities (OGR/ORR/SCs).Low overpotential, low Tafel values, relatively high current density and good stability of electrode materials are significant for OGR and ORR.ZnWO4 Nbs exhibit efficient supercapacitor performances with the specific capacitance (250 F/g) and energy density (80 Wh/kg) at 5 mV/s in 1 M KOH.ZnWO4 Nbs also work as photo-catalysts to enhance the degradation of aqueous organic dyes.

Zinc Tantalum Oxynitride (ZnTaO2N) Photoanode Modified with Cobalt Phosphate Layers for the Photoelectrochemical Oxidation of Alkali Water

Photoanodes fabricated by the electrophoretic deposition of a thermally prepared zinc tantalum oxynitride (ZnTaO2N) catalyst onto indium tin oxide (ITO) substrates show photoactivation for the oxygen evolution reaction (OER) in alkaline solutions. The photoactivity of the OER is further boosted by the photodeposition of cobalt phosphate (CoPi) layers onto the surface of the ZnTaO2N photoanodes. Structural, morphological, and photoelectrochemical (PEC) properties of the modified ZnTaO2N photoanodes are studied using X-ray diffraction (XRD), scanning electron microscopy (SEM), ultraviolet visible (UV−Vis) diffuse reflectance spectroscopy, and electrochemical techniques. The presence of the CoPi layer significantly improved the PEC performance of water oxidation in an alkaline sulphate solution. The photocurrent-voltage behavior of the CoPi-modified ZnTaO2N anodes was improved, with the influence being more prominent at lower oxidation potentials. A stable photocurrent density of about 2.3 mA·cm−2 at 1.23 V vs. RHE was attained upon visible light illumination. Relative to the ZnTaO2N photoanodes, an almost three-fold photocurrent increase was achieved at the CoPi/ZnTaO2N photoelectrode. Perovskite-based oxynitrides are modified using an oxygen-evolution co-catalyst of CoPi, and provide a new dimension for enhancing the photoactivity of oxygen evolution in solar-assisted water-splitting reactions.

Synthesis and Characterizations of Titanium Tungstophosphate Nanoparticles for Heavy Metal Ions Removal

Ionic exchange of multi-components titanium tungstophosphate nanoparticles (TiWP-NPs) were prepared using sol-gel reaction of titanium isoperoxide and tungestophosphoric acid (TPA) in presence of CTAB surfactant. The X-ray, BET and TEM characterizations showed that the nanoparticles exhibit the characteristic structure of titanium tungstophosphate and a BET surface area of 74 ± 3 m2/g was achieved. The TPA has shown an effect on the self-assembly process and maintains the TPA content to minimum would be beneficial for obtaining higher surface area of TiWP nanoparticles. Metal ions adsorption of Cu(II), Pb(II) or Cd(II) using the resulting titanium tungstophosphate nanparticles materials is investigated and up to 95% removal percentage was achieved. Using this method, nanoparticles of ionic exchange titanium tungstophosphate can be synthesized in the form of powder and amenable to mass production.