Revealing Anion-Mediated Dynamic Reconstruction of Transition Metal Phosphide Electrocatalysts During Oxygen Evolution Reaction

Transition metal phosphides exhibit excellent efficiency in the oxygen evolution reaction under alkaline conditions, and they have garnered widespread recognition. Currently, most studies have focused on the evolution and role of metal cations in the oxygen evolution reaction process, while attention to phosphorus elements is relatively scarce. Actually, phosphides possess unique properties that distinguish them from other metal compounds, and the role of phosphorus in them cannot be ignored. This study used nickel phosphide (Ni₂P) as a model catalyst to reveal the reconstruction and dynamic behavior of anions under alkaline conditions through cyclic voltammetry. The results indicate that as the cycle progresses, surface phosphides are converted into active oxyhydroxides. It is worth noting that the presence of the P element accelerates the rapid completion of the reconstruction process but also exhibits triple synergistic functions. First, the internal phosphorus nuclei of the active layer act as conductive scaffolds, effectively enhancing the efficiency of electron conduction. Second, the oxygen-containing anions formed in situ on metal hydroxides optimize the adsorption of reaction intermediates. Finally, the phosphorus atoms dissolved in the electrolyte suppress nickel loss, improve stability, and increase the electrochemical activity specific surface area, exposing more active sites. This study elucidates the oxygen evolution reaction mechanism of phosphides from a novel perspective, enhancing comprehension of surface reconstruction phenomena and the characteristics of active sites, guiding the rational design of phosphide pre-catalysts.