Iron and Manganese Codoped Cobalt Tungstates Co_1–(x+y)Fe_xMn_yWO₄ as Efficient Photoelectrocatalysts for Oxygen Evolution Reaction

Abstract

Photoelectrocatalysts are robust materials for the production of energy through different ways such as water splitting. Narrow optical band gaps and high overpotentials are limiting the development of photoelectrocatalysts. In this study, a series of Co1–(x+y)Fe x Mn y WO4 solid solutions of cobalt tungstate codoped with iron and manganese have been synthesized hydrothermally. The synthesized solid solutions have been characterized by powder XRD, UV–visible spectra, cyclic voltammetry (CV), and linear sweep voltammetry (LSV). They all crystallize in a wolframite-type monoclinic crystal system with space group P2/c. Doping of iron and manganese leads to narrowing of the optical band gap of Co1–(x+y)Fe x Mn y WO4 from 2.60 to 2.04 eV. The electrocatalytic activity toward oxygen evolution reaction of all of the samples has been evaluated through LSV measurements. It is found that the sample named C5, which is codoped with manganese and iron, has the lowest onset potential and needs the lowest overpotential to attain the targeted 5 mA cm–2 and standard 10 mA cm–2 current densities as compared with all other synthesized samples. This study shows that the synthesized tungstates can be good candidates for the photoelectrocatalytic oxygen evolution reaction.

Crest to Trough Cellular Drifting of Green-Synthesized Zinc Oxide and Silver Nanoparticles

“…Current results were compared with previously reported work, and it has been observed (UV) that zinc oxide and silver NPs showed better and authentic confirmation. , These particles were further characterized using X-ray diffraction analysis (XRD) in the range of 20–80°. The intense and narrow diffraction peaks of ZnONPs revealed a cubic phase and high purity with distinct diffraction peaks in the 022, 101, 102, 110, 103, and 201 planes, whereas AgNPs also revealed a cubic phase and high purity with distinct diffraction peaks at the 111, 022, and −402 planes (Figure c). The structures of zinc oxide and silver were matched with already reported work, and it was found that the current structure for silver and zinc showed confirmation and can be used for physical, chemical, and biological applications. , High-resolution microscopy using a transmittance electron microscope (TEM) showed fine flower-shaped structures of ZnONPs measuring 25 nm (Figure d) and AgNPs measuring 30 nm with a regular spherical structure (Figure e).…”

“… 35 , 36 These particles were further characterized using X-ray diffraction analysis (XRD) in the range of 20–80°. The intense and narrow diffraction peaks of ZnONPs revealed a cubic phase and high purity with distinct diffraction peaks in the 022, 101, 102, 110, 103, and 201 planes, 37 whereas AgNPs also revealed a cubic phase and high purity with distinct diffraction peaks at the 111, 022, and −402 planes ( Figure 1 c). The structures of zinc oxide and silver were matched with already reported work, and it was found that the current structure for silver and zinc showed confirmation and can be used for physical, chemical, and biological applications.…”

Synthesis, Characterization, Immune Regulation, and Antioxidative Assessment of Yeast-Derived Selenium Nanoparticles in Cyclophosphamide-Induced Rats

“…13,14 The unique properties, functions, and applications of NPs such as silver, 15 gold, iron, 16 and Se-NPs have a lasting connection with their size and shape. Chemical and physical methods to synthesize Se-NPs, apart from being expensive, easy to aggregate, 17 and of unstable shape and size, there are other problems such as complex synthesis process, 18 not being environmentally friendly, and the requirement of strict conditions 19 limit the application of Se-NPs. By contrast, the biotemplate method (green synthesis method) for preparing Se-NPs from microorganisms, proteins, polysaccharides, and plant extracts 20 is considered as a potential substitute for chemical and physical methods because of its eco-friendliness, 21 less toxicity, high stability, 22 and narrow size and shape distribution.…”

Facile Synthesis and Characterization of Novel Carbon Nanofiber-Doped MWO4 (M–Mn, Co, Ni, Mn–Co, Mn–Ni, Ni–Co)-Based Nanostructured Electrode Materials for Application in Electrochemical Supercapacitors and Photoelectrochemical Water Splitting

“…These absorption peaks are related to typical forbidden d−d electronic transitions originating from the localized Co 2+ ions. 47 CW also exhibits edge absorption at approximately 510 nm, which is represented by the O 2p to W(5d) transition. 48 It has been found that mixing MW and NW in conjunction with CNF, referred to as a MNWC composite, results in better absorption of visible light compared to pristine MW and NW.…”

“…In the case of CW, two strong absorption peaks are observed at 580 and 790 nm. These absorption peaks are related to typical forbidden d−d electronic transitions originating from the localized Co 2+ ions 47. CW also exhibits edge absorption at approximately 510 nm, which is represented by the O 2p to W(5d) transition 48.…”