An acid-etched low-Pt high-entropy alloy with significantly boosted activity for alkaline hydrogen evolution

High-entropy alloys (HEAs) have attracted wide attention in the field of electrocatalysis owing to their tunable catalytic activity, multielement synergy and high stability. However, it remains challenging to develop efficient HEA catalysts for the alkaline hydrogen evolution reaction (HER) due to their vast multielement space and unidentified active sites. Herein, we report the synthesis and characterization of a low-Pt Nb 35 V 30 Mo 10 Cu 10 Pt 15 HEA catalyst by combining arc-melting and acid etching. Remarkably, the acid-etched HEA exhibits an ultralow overpotential of 28 mV and a small Tafel slope of 40.9 mV dec −1 at 10 mA cm −2 in 1.0 M KOH solution, comparable with the commercial Pt/C catalyst. First principles calculations show that the enhanced catalytic performance is due to the significant reduction of the energy barrier for breaking the H-OH bond from the multi-active sites. Our work demonstrates that the combination of multisite synergy and acid-induced surface modification provides a novel strategy to develop efficient catalysts for alkaline HER. • A low-Pt Nb-V-Mo-Pt-Cu HEA for alkaline HER is prepared by combining arc-melting and acid etching method. • The acid etching makes HEA form a loosen surface structure with more exposed Pt active sites. • It achieves a low overpotential of 28 mV@10 mA cm −2 , a Tafel slope of 40.9 mV dec −1 and good durability in 1.0 M KOH. • The multisite synergy and boosted catalytic activity contribute to the remarkable catalytic performance.