Sulfur-induced structural and electronic engineering of Ru nanoclusters for highly efficient hydrogen evolution

Abstract

The electron metal–support interaction (EMSI) in carbon-supported metal catalysts plays a crucial role in the catalytic performance. However, understanding the enhancement mechanism of EMSI in electrocatalysis remains challenging. Herein, we report an in situ synthesis of ultrafine Ru nanoparticles (∼4.08 nm) anchored on S,N co-doped carbon microflowers (denoted as Ru@S,N-CMFs hereafter), where the heteroatom S is captured by N vacancies, for efficient hydrogen evolution electrocatalysis. Atomic-resolution morphological and spectroscopic characterization collectively indicates that compared to the common Ru@N-CMFs, the sulfur atoms occupying the nitrogen vacancies in Ru@S,N-CMFs can interact with Ru to form Ru–S bonds. This can strengthen the EMSI to promote electron enrichment and induce structural defects at Ru sites, thus synergistically achieving efficient catalytic activity for the alkaline hydrogen evolution reaction (HER). Therefore, the Ru@S,N-CMFs exhibit outstanding HER activity (18 mV at 10 mA cm⁻²), excellent reaction kinetics (23 mV dec⁻¹) and distinguished electrochemical stability, surpassing the commercial benchmark and most reported catalysts in a 1.0 M KOH electrolyte. Furthermore, the Ru@S,N-CMF-assembled anion exchange membrane water electrolyzer functions at a low voltage (1.75 V at 1 A cm⁻²) and maintains stable operation at 1 A cm⁻² for over 246 h.