A ruthenium–titania core–shell nanocluster catalyst for efficient and durable alkaline hydrogen evolution†

Abstract

Anion-exchange-membrane water electrolysis (AEMWE) is an emerging technology for hydrogen production. While nanoparticles are used as catalysts to enhance catalytic activity, they face durability challenges due to high surface energy and reactivity. Here we present a core–shell nanocluster catalyst featuring a Ru metal core encapsulated in a porous/reduced titania monolayer, incorporating Mo atoms. This core–shell structure not only protects the unstable metal core but also lowers the energy barriers for water dissociation. The synergistic interface formed by the titania heterostructure and Mo doping modulates the electron density distribution of ruthenium active sites, fine-tuning the d-band electronic structure and optimizing the intermediate binding strengths. As a result, exceptionally low overpotentials of just 2 mV at 10 mA cm⁻² and 120 mV at 500 mA cm⁻² could be achieved. In a practical AEMWE system, the core–shell catalyst shows an outstanding current density of 3.35 A cm⁻² under a cell voltage of 2.0 V at 60 °C, preserving its activity over 530 h of long-term electrolysis at 0.5 A cm⁻².