A multisite HEA catalyst with etching-induced active surface for synergistic alkaline hydrogen evolution

Abstract

Developing high-activity electrocatalysts is crucial for the sustainable hydrogen production. This study presents a scalable strategy that combines arc-melted high-entropy alloy (HEA) synthesis with selective acid etching to create a superior catalyst for alkaline hydrogen evolution reaction (HER). The designed Nb<inf>30</inf>Mo<inf>25</inf>V<inf>20</inf>Pt<inf>15</inf>Ir<inf>10</inf> HEA undergoes controlled etching, which selectively removes specific elements to construct a highly active surface with exposing and stabilizing Pt/Ir active sites. The optimized catalyst demonstrates exceptional performance, achieving an ultralow overpotential of 24 mV at 10 mA cm−2, a Tafel slope of 35.6 mV dec−1, and remarkable stability in 1.0 M KOH electrolyte. More importantly, it exhibits a superior precious metal mass activity of 0.081 A mg−1<inf>Pt + Ir</inf> and a high turnover frequency of 1.14 s−1 at 100 mV, surpassing the commercial Pt/C. Experimental characterization and DFT calculations reveal a synergistic multisite mechanism where Pt sites facilitate optimal H∗ adsorption while Mo–Ir bridge sites modulate surface OH∗ interaction, collectively enhancing the reaction kinetics. This work provides new insights into designing high-performance, cost-effective electrocatalysts through rational HEA engineering and post-synthetic surface modification.