First-principles design of a superior electrocatalyst to Pt for hydrogen production in alkaline media

Abstract

Pt electrocatalysts are known to be surprisingly inactive for the hydrogen evolution reaction (HER) in alkaline media due to their high activation barrier for water decomposition. Despite extensive research over several decades, only a few electrocatalysts with exceptional efficiency and stability have been reported, primarily due to an incomplete understanding of the mechanism and catalyst design principles. Therefore, we investigated the underlying mechanism of the proposed catalyst design for Pt monolayer surface alloy (Pt/W(110)) and nanoparticle (W@Pt) structures, focusing on (i) the surface strain effect and (ii) the ligand effect (charge transfer). Using first-principles calculations, we demonstrated that fabricating Pt nanoparticles increases the H₂O adsorption energy, with lower dissociation energy barrier expected, only shifts the rate-determining step (RDS) to H₂ desorption. When pure Pt structures are modified with W substrates, the dual effects of strain and ligand interactions control the activities of the bulk pseudo-binary Pt/W(110) surface alloy and W@Pt core–shell nanoparticles in the opposite manner. The W@Pt nanoparticles uniformly destabilized all intermediates, increasing the water dissociation activation barrier. In contrast, the Pt/W(110) surface heterogeneously regulated the adsorption intensities of the intermediates, breaking the scaling law of catalysis. We clearly elucidated this heterogeneous behavior in terms of eigenstress-induced surface strain and charge transfer. Our study is expected to provide quantum-mechanical insights into the design of active electrocatalysts by controlling key atomic-level descriptors and addressing the long-standing issue of inactive Pt catalysts in alkaline media.