RuCo clusters stabilized by Co single atoms: alloying effect and small size effect facilitate hydrogen electrocatalysis kinetics

The development of efficient catalysts is essential to promote slow hydrogen reaction kinetics in alkaline solutions. Herein, an ultrathin ZIF-derived efficient HOR/HER electrocatalyst, with Co single-atom-anchored RuCo clusters on N-doped graphitized carbon nanosheets (RuCo/SANC NS), is designed and constructed by a step-bystep calcination strategy. In the RuCo/SANC NS, Co atoms dispersed in carbon nanosheets induce the formation of ultrasmall RuCo clusters and stabilize the RuCo clusters. Abundant coordinatively unsaturated Ru sites are formed on the surface of RuCo clusters due to the small size effect. The electronic structure of the Ru site is regulated by the alloying effect with Co, optimizing the adsorption energy to *H and *OH and accelerating the HER/HOR kinetics. The RuCo/SANC NS catalyst exhibits excellent mass activity with HER of 13.58 A/mgRu and HOR of 3.85 A/mgRu, which are about 35.35 and 48.13 times that of Pt/C.