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A Cu-C i oxygen-evolution catalyst (C i is inorganic carbonate) is prepared from of the abundant elements copper. They are generated in situ in carbonate solution (pH 10.25) with copper(I) complex under mild conditions (room temperature, atmospheric pressure, and near-neutral solution). The result indicates that the prepared Cu-C i catalyst is amorphous. The average oxygen-evolution rate is 33.88 μmol h −1 cm −2 . An oxygen evolution overpotential of 263.8 mV is required at a current density of 1 mA cm −2 . Factors affected catalytic activity during water splitting, including temperature and type of electrolyte, are investigated. The phase, structure, morphology, composition, and catalytic activity of Cu-C i catalyst are analyzed using a variety of characterization methods, namely, X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, high resolution transmission electron microscopy and electrochemical measurement. [ABSTRACT FROM AUTHOR]

In this paper we synthesized a crystalline Ag-C i oxygen-evolution catalyst with an entirely new composition and structure in situ in a carbonate solution (pH = 8.3) with Ag+ at 70 °C. We studied the factors that influenced the synthesis of the oxygen-evolution catalyst (electrolyte environment temperature, silver ion concentration, concentration of carbonates) under mild conditions. The structure, morphology, composition, and catalytic activity of Ag-C i catalyst were analyzed using techniques such as X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and electrochemical measurements. Our results showed that the diffraction peaks of the Ag-C i catalysts synthesized at 70 °C were consistent with the AgO phase and that the catalytic composition of the Ag-C i catalyst was the AgⅠO/AgⅡO redox couple. The oxygen-evolution rate of the catalyst synthesized in a carbonate solution (pH = 8.3) at 70 °C was 50 times higher than that synthesized at 5 °C (18.3 μmol h−1); additionally, its oxygen evolution overpotential decreased to 246.7 mV. The electrolyte solution and Ag+ ion concentration greatly impacted the catalytic activity of the Ag-C i catalyst for water splitting. [ABSTRACT FROM AUTHOR]

Abstract: A weakly acidic H3BO3 solution (pH = 5.1) was used to synthesize new oxygen-evolution catalysts for water splitting under mild conditions. Two novel oxygen-evolution catalysts, Co–BA i and Mn–BA i (BA i = inorganic boric acid), were obtained in the H3BO3 solution with added Co2+ and Mn2+, respectively. The average oxygen evolution rate in the H3BO3 solution with Co2+ was 0.3133 μmol/h, about 70 times greater than the rate without a metal ion; the rate with Mn2+ was 1.13 μmol/h, about 250 times greater. The phases, morphologies, and compositions of the Co–BA i and Mn–BA i catalysts were analysed by X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy. [Copyright &y& Elsevier]

Silver-based catalysts with an adjustable structure are promising as efficient oxygen evolution catalysts. Four types of silver-oxide (AgO) morphologies were obtained by potentiostatic deposition in situ in organic carboxylate by altering the amount of ammonia as the complexing agent. AgO films can be used in the oxygen-evolution reaction; AgO that is formed by using potassium acetate that contains 1.32 mM ammonia as an electrolyte exhibits preferable performance. Catalyzed water oxidation occurs in 0.1 mol/L potassium phosphate solution (pH 12.3) with an average activity of 3.5 mA/cm 2 , and persists for at least 10 h at 2.03 V (vs. Reversible Hydrogen Electrode, RHE). Overpotential is 438 mV at a current density of 1 mA/cm 2 . The Faradaic efficiency is 94.4%. Samples were well characterized by X-ray powder diffraction, scanning electron microscopy and X-ray photoelectron spectroscopy. [ABSTRACT FROM AUTHOR]

We describe the preparation of three partially ordered iron-based catalyst films (Fe-OAc, Fe-Pro, Fe-But) with nanoporous structure by electrodeposition from organate electrolytes containing Fe 2+ . The anions of the organic acids assisted the partial ordering of the nanostructured Fe(III) catalysts for water oxidation. A model involving an electrical double layer is invoked to explain the role of the organate electrolyte system in their formation. Analytical results have revealed the main component of the iron-based films to be a β-FeOOH structure. The Fe-But catalyst catalyzed water oxidation in 0.1 m potassium carbonate solution with an average activity of 1.48 mA cm −2 and an overpotential of 433 mV. [ABSTRACT FROM AUTHOR]

We describe a novel nanostructured iron oxide catalyst film electrodeposited from iron(II) triflate under mild conditions (room temperature, atmospheric pressure, and near-neutral solution) that can catalyze water oxidation in potassium carbonate solution. The structure, morphology, composition, and catalytic activity of the catalyst were characterized by X-ray diffractometry, scanning electron microscopy, energy-dispersive X-ray spectroscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, and electrochemical measurements. The results indicate that nanostructured iron oxide is an active electrocatalyst for water oxidation at higher catalytic current and low overpotential. [ABSTRACT FROM AUTHOR]