Amorphization-enabled decoupling of hydrogen and hydroxide binding on RuSi for efficient alkaline hydrogen evolution

Abstract

Catalyst optimization for the alkaline hydrogen evolution reaction (HER) is fundamentally constrained by scaling relations between hydrogen binding energy (HBE) and hydroxide binding energy (OHBE), yet rational design strategies capable of synergistically optimizing both descriptors have remained experimentally elusive. Herein, we demonstrate that independent regulation of HBE and OHBE dramatically accelerates alkaline HER kinetics by employing a structurally flexible amorphous RuSi (a-RuSi) as a dual-site model catalyst. Through annealing-induced evolution of structural order and local Ru–Si coordination, the adsorption energetics of H* and OH* are decoupled, which breaks the conventional scaling relationship and shifts the catalytic activity maximum to a higher-performance regime. The disordered structure generates diverse Ruδ−–Siδ+ Lewis acid–base pairs via ligand-to-metal charge transfer, enabling synergistic H2O activation and balanced intermediate binding. This yields an ultralow overpotential of 7.85 ± 0.35 mV at 10 mA cm−2 with remarkable durability over 1000 h at 1 A cm−2 in 1 M KOH. Critically, this work constructs an experimental 3D activity-HBE–OHBE descriptor map for the RuSi catalyst series, highlighting the importance of balanced H and OH binding in bifunctional alkaline HER catalysis.