Design of grain boundary enriched bimetallic borides for enhanced hydrogen evolution reaction

[Display omitted] •An effective strategy was developed to synthesize nanostructures with abundant grain boundaries.•DFT results confirm that grain boundaries have a higher intrinsic catalytic activity.•High HER catalytic performance (75 mV@10 mA cm−2) was achieved for metal borides. Grain boundaries can induce strained regions in the nanostructure of catalysts that can provide highly active surfaces with optimized electronic structures for catalysis. Although studies on grain boundary have been reported for catalysis, it is still challenging to construct nanostructures with rich grain boundaries and reveal their function mechanism. Herein, we present a facile strategy to synthesize bimetallic borides Ni3B/MoB nanosheets with abundant grain boundaries and unravel the impact of grain boundaries on electrocatalytic performance for hydrogen evolution reaction (HER). Experimental results, combined with theoretical calculations, revealed that the synthesized Ni3B/MoB featured numerous grain boundaries and optimized morphology. More importantly, the electronic states at the grain boundary were adjusted and ΔGH* was optimized. This resulted in highly intrinsic catalytic activities for HER in both acidic and alkaline conditions. This work sheds new light on the synthesis and regulation of transition metal borides and functional materials enriched grain boundaries for catalysis.