Copper dopants facilitated generation of high-valent cobalt sites for improved oxygen evolution

Abstract

Developing a reliable strategy to adjust dynamic reconstruction and formation of active oxygen species on electrocatalyst surfaces is crucial for enhancing the OER performance and still needs further elaborate elucidation. Here, we report a strategy for adjusting surface reconstruction of Co₄N, in which inert Co₃O₄ on the reconstruction surface is activated via Cu introduction (Cu-Co₄N), facilitating the deprotonation process to generate CoO₂, as evidenced using in situ Raman spectroscopy. The filled t_2g orbital of Cu²⁺ causes an asymmetric distribution of Cu–O–Co, which could facilitate electron transfer and optimize the adsorption of intermediates. Density functional theory calculations corroborate that Cu dopants can optimize the conversion energy barrier from *OH to *O via adjusting the adsorption of intermediates. The resulting electrocatalyst requires an overpotential of 234 mV to drive 10 mA cm⁻². The membrane electrode assembly electrolyser employing Cu-Co₄N operated steadily for at least 144 h at 1 A cm⁻². This work provides a promising way to adjust surface reconstruction and formation of active oxygen species for transition metal nitride-based OER catalysts.