In Situ/Operando Study of Nitrogen-Enriched Resin-Sustained Nickel Diselenide in Alkaline Water Oxidation: A Thermodynamic and Density Functional Theory Perspective

This study elucidates the pivotal role of NiSe2 nanoparticles embedded in a nitrogen-rich resin (NiSe2@NER-400) as efficient pre-electrocatalysts for the oxygen evolution reaction (OER) in 1.0 M KOH. In situ/operando UV–vis spectroscopy reveals the progressive formation of selenite (SeO32–) species, followed by their conversion to selenate (SeO42–) species under OER conditions. The presence of surface selenates is significant due to their strong interaction with the central metal sites, which enhances the OER activity. Notably, the electrocatalyst exhibits superior catalytic performance, delivering a low onset overpotential of 253 mV versus RHE and a Tafel slope of 91 mV dec–1. Density functional theory calculations provide optimized structural models supported by simulated FT-IR spectra, HOMO–LUMO energy gap analysis, and molecular electrostatic potential mapping, confirming the stability of the composite. These models further offer mechanistic insights into the mechanism of the OER pathway in alkaline media. Collectively, these results demonstrate that the electrocatalyst is a promising electrocatalyst for efficient OER applications.