Heteroanion induced structural asymmetricity centered on Ru sites switches the rate-determining step of acid water oxidation

Abstract

The exploration of Ir-free-based oxygen evolution reaction (OER) catalysts is the key for electrolytic hydrogen production. Herein, a Se, S heteroanion modulation strategy is proposed to improve the OER activity and stability of cationic Ru sites through induced structural asymmetricity. Due to the differences between the intervening Se and S in atomic radius, metallicity and ionization energy, they not only alter the octahedral arrangement and bond length of the pristine RuS₂, but also act as a charge modulator to promote electron accumulation toward Ru. Impressively, the electronic structure and coordination environment optimized Ru₂(S₃Se) achieves hyper water oxidation activity (186 mV@10 mA cm⁻²), 28.2 and 10.5 times that of commercial RuO₂ in mass and specific activities, respectively. Moreover, the synergistic effect of Se and S effectively inhibits the formation of soluble Ru species, thereby upgrading the OER stability. Theoretical calculations and in situ detection technology further unveil the reaction path and structure changes on Ru₂(S₃Se) surfaces, rationalizing the enhanced performance by decreased energy barriers of the rate-determining step (RDS) and strong coupling of Se–Ru–S bonds.