Chemical Surface Reconstruction of Transition Metal Borides Catalysts Toward Practical Overall Water Splitting

The wide application of alkaline water electrolysis is significantly restricted by the lack of highly efficient catalyst that can withstand an industrial current density (>400 mA cm −2 ) for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Herein, a simple “chemical surface reconstruction” strategy was proposed to develop transition metal borides (TMBs) with exceptional activity and durability towards this challenge. We adopt a simple chemical etching process in the presence of Fe to reconstruct the composition and structure of TMBs, enabling favorable electronic structure and high density of active sites exposure. An optimized surface reconstructed Fe-NiMoB catalyst can drive 500 mA cm −2 at overpotentials of only 123 and 330 mV for HER and OER, respectively. Remarkably, Fe-NiMoB catalyst can deliver a stable 1.3 A cm −2 at a cell voltage of 2.0 V for 120 hours in simulated industrial condition (80 o C in 30% KOH solution)