Hydrogen spillover nanoalloy: cathodic protection against reverse current degradation for intermittent water electrolysis.

Abstract

Alkaline water electrolysis stands as a promising avenue for large-scale green hydrogen production. Nickel-molybdenum (NiMo) alloys are efficient electrocatalysts towards the hydrogen evolution reaction on the cathode side, yet their metallic composition suffers from instability under intermittent power conditions. Herein, we introduce a hydrogen spillover-enabled nickel-gold (NiAu) alloy into NiMo cathodes, where hydrogen can be dynamically stored and released during intermittent operation to consume reverse current during power shutdown. Combining density functional theory and interfacial molecular dynamics simulations with experiments, we demonstrate that the release and oxidation of hydrogen species from the hydrogen spillover alloy during shutdown serve to protect the NiMo cathode from oxidation, thereby enhancing electrochemical stability under intermittent conditions. Our findings provide atomic-level insights into hydrogen spillover-mediated cathode protection under dynamic operating conditions, offering new design principles for stabilizing metastable alloy interfaces and engineering degradation-resistant catalytic architectures.