Boosting hydrogen evolution activity: next-nearest oxygen coordination in dual-phase supra-nanostructured multiprincipal element alloy catalysts†

Achieving near-zero overpotential for a large-scale hydrogen evolution reaction (HER) using multi-principal element alloys is a formidable challenge. These alloys, characterized by their diverse compositions and complex atomic configurations, offer a broad spectrum of catalytic sites, positioning them as candidates of interest in energy and environmental applications. However, conventional methods for improving the catalytic performance of these alloys, which focus on element composition and the cocktail effect, frequently undervalue the role of structural design. In this work, we introduce an innovative approach that integrates oxygen incorporation with dual-phase supra-nanostructuring to boost the catalytic efficacy of a multi-principal element alloy via industrial magnetron sputtering at ambient temperature. Specifically, the oxygen-incorporated crystal-amorphous dual-phase supra-nanostructured palladium/multi-principal element alloy (denoted as SNDP-Pd@HEAA) presents a plethora of uniformly distributed interfaces enriched with unique next-nearest oxygen-coordinated active sites, which contribute to its exceptional HER performance. The SNDP-Pd@HEAA exhibits a near zero overpotential of 10.16 mV at a current density of 10 mA cm⁻², which is much lower than that of 34.01 mV of commercial 20% Pt/C. Remarkably, it retains a reliable long-term stability of ∼1000 h at 500 mA cm⁻² in an anion exchange membrane (AEM) device, which is significantly higher than that of the reported commercial Pt/C||IrO₂ system. The structural and computational results reveal that the SNDP-Pd@HEAA comprising Pd-rich nanocrystalline cores and O-rich amorphous glassy shells produces plentiful active interfaces and special active Pd sites with next-nearest O coordination, thus actively promoting water adsorption capacity and accelerating hydrogen proton adsorption/desorption. This SNDP nanostructure production and oxygen-incorporated manipulation technique, as well as the next-nearest O-coordinated active sites mechanism, establishes a new paradigm for hydrogen evolution reaction catalysts.