Voltage activation induced MoO42− dissolution to enhance performance of iron doped nickel molybdate for oxygen evolution reaction

Transition metal-based precatalysts are typically voltage-activated before electrochemical testing in the condition of alkaline oxygen evolution reaction . Nevertheless, the impact of voltage on the catalyst and the anion dissolution is frequently disregarded. In this study, Fe-doped NiMoO 4 (Fe-NiMoO 4 ) was synthesized as a precursor through a straightforward hydrothermal method , and MoFe-modified Ni (oxygen) hydroxide (MoFe-NiO x H y ) was obtained via cyclic voltammetry (CV) activation. The effects of voltage on Fe-NiMoO 4 and the dissolved inactive MoO 4 2− ions in the process were examined in relation to OER performance. It has demonstrated that the crystallinity of the catalyst is reduced by voltage, thereby enhancing its electrocatalytic activity . The electron distribution state can be adjusted during the application of voltage, leading to the generation of additional active sites and an acceleration in the reaction rate. Additionally, MoO 4 2− exhibits potential dependence during its dissolution. In the OER process, the dissolution of MoO 4 2− enhances the reconstruction degree of Fe-NiMoO 4 into the active substance and expedites the formation of active Ni(Fe)OOH. Hence, the optimized MoFe-NiO x H y exhibited exceptional electrocatalytic performance, with a current density of 100 mA cm −2 achieved at an overpotential of only 256 mV. This discovery contributes to a more comprehensive understanding of alkaline OER performance under the influence of applied voltage and the presence of inactive oxygen ions , offering a promising avenue for the development of efficient electrocatalysts .