Vacancy induced microstrain in high-entropy alloy film for sustainable hydrogen production under universal pH conditions

Abstract

Electrocatalytic hydrogen production plays an essential role in generating eco-friendly fuels for energy storage and transportation within a sustainable energy framework. High-entropy alloys (HEAs), with their abundant compositional variety, significantly expand the scope of material libraries and have received substantial research interest in energy and environmental technologies. However, the conventional approach to modulating HEA catalysts through element selection and exploiting the cocktail effect overlooks the potential of the high designability of high-entropy solid solutions. Herein, we present a novel strain engineering strategy to further enhance the catalytic performance of a desirable HEA composition by incorporating vacancy-induced microstrain into an HEA film. The strain engineered HEA film delivers an economically viable industrial water electrolysis capacity at an ampere-level current density of 1 A cm⁻² with overpotentials of 104 and 106 mV under alkaline and acidic conditions, respectively. Remarkably, it retains long-term sustainability of ∼500 h at 100 mA cm⁻² in an anion exchange membrane (AEM) device, demonstrating a lifespan 40 times that of a commercial Pt/C||IrO₂ system. Microstructural analyses and computational calculations indicate that the active sites with a low coordination environment enhance charge transferability, and thus promote the water adsorption capacity. Furthermore, the microstrain effect downshifts in the d-band center of Pt to a near-optimal position, which subsequently lowers the binding affinity between Pt and intermediates, resulting in enhanced hydrogen evolution reaction activity. Our work demonstrates a practical strain engineering strategy that provides a new avenue to enhance the performance of catalysts for sustainable energy conversion.