Interface Charge Transfer of Heteroatom Boron Doping Cobalt and Cobalt Nitride for Boosting Water Oxidation

Designing high-performance transition-metal electrocatalysts with controlled active heterointerfacial sites for catalyzing the electrochemical oxygen evolution reaction (OER) is very desirable but remains a great challenge. Here, a facile strategy for the synthesis of transition-metal nitride-based interfacial electrocatalysts boron-doped cobalt/cobalt nitride (B-Co/Co₂N) is demonstrated with optimal heterointerfaces between Co and Co₂N electrocatalysts by introducing boron as a dopant to the former. Benefiting from the unique electronegativity of B, the obtained B-Co/Co₂N electrocatalysts show excellent OER performance with overpotential inputs of as low as 262 and 310 mV for 10 and 100 mA cm^-2, which are 1.4 and 6.6 times higher than those of Co/Co₂N with the same potential input, respectively. The experimental and theoretical results demonstrate the role of the B dopant in inducing charge redistribution of Co active sites in the Co/Co₂N interfacial region, which results in a downshift of the Co 3d band center, the optimal oxidation state of active sites for *OOH formation, and lower energy barriers. Furthermore, the assembled electrolyzer can steadily produce an industrial-grade current density of 1000 mA cm^-2 at a cell voltage input of only 1.81 V for at least 100 h with a Faradaic efficiency near 100%. This study provides a promising strategy for heteroatom-doped interfacial electrocatalysts with high performance for energy and environmental applications.