Elucidating the superwetting FeOOH-modified NiMoO₄ electrodes for efficient alkaline oxygen evolution reaction: An in-situ spectroscopy study

Exploring the dynamic surface reconstruction of the pre-catalysts throughout the oxygen evolution reaction (OER) and analyzing the real active species are essential for water electrolysis. Here, we report FeOOH modified NiMoO₄ nanowire arrays for efficient OER in alkaline. In-situ Raman, UV–vis and electrochemical impedance spectroscopies were employed to analyze the dynamic reconstruction process. Our results revealed that this process involves a fast dissolution of MoO₄^2- and the synthesis of Ni(Fe)OOH species, which are determined as the genuine catalysts for the OER reaction. The reconstructed superwetting catalyst exhibited excellent catalytic activity, achieving an overpotential of 281.1 mV at 100 mA cm⁻² and sustained operation for 1000 h. Density functional theory (DFT) simulations demonstrated that the reduced adsorption strength of OH* → O* step on Ni(Fe)OOH intermediates contributed to a lowered reaction energy barrier. Our work provides a simple method for modifying catalysts, accompanied by a comprehensive examination of the dynamic reconstruction process aimed at enhancing the kinetics of the pre-catalyst.