Electronic redistribution through the interface of MnCo2O4–Ni3N nano-urchins prompts rapid In situ phase transformation for enhanced oxygen evolution reaction

Abstract

One of the most coveted objectives in the realm of energy conversion technologies is the development of highly efficient and economically viable electrocatalysts for the oxygen evolution reaction. The commercialization of such techniques has thus far been impeded by their slow response kinetics. One of the many ways to develop highly effective electrocatalysts is to judiciously choose a coupling interface that maximizes catalyst performance. In this study, the in situ electrochemical phase transformation of MnCo₂O₄–Ni₃N into MnCo₂O₄–NiOOH is described. The catalyst has an exceptional overpotential of 224 mV to drive a current density of 10 mA cm⁻². Strong interfacial contact is seen in the MnCo₂O₄–Ni₃N catalyst, leading to a considerable electronic redistribution between the MnCo₂O₄ and Ni₃N phases. This causes an increase in the valence state of Ni, which makes it an active site for the adsorption of *OH, O*, and *OOH (intermediates). This charge transfer facilitates the rapid phase transformation to form NiOOH from Ni₃N. At a higher current density of 300 mA cm⁻², the catalyst remained stable for a period of 140 h. DFT studies also revealed that the in situ-formed NiOOH on the MnCo₂O₄ surface results in superior OER kinetics compared to that of NiOOH alone.