Electronic Structure Modulation Induced by the Synergy of Cobalt Low-Nuclearity Clusters and Mononuclear Sites for Efficient Oxygen Electrocatalysis
Zhijun Li, Hongxue Liu, Yuhao Wang, Siqi Ji, Yuqi Zhang, Yuesong Liu, Xue Lü, Huiya Teng, J. Hugh Horton, Yu Wang, Xinzhi Ma, Yujia Tang
Abstract
The development of high-performance bifunctional single-atom catalysts for use in applications, such as zinc–air batteries, is greatly impeded by mild oxygen reduction and evolution reactions (ORR and OER). Herein, we report a bifunctional oxygen electrocatalyst designed to overcome these limitations. The catalyst consists of well-dispersed low-nuclearity Co clusters and adjacent Co single atoms over a nitrogen-doped carbon matrix (Co SA+C /NC). The precisely tailored asymmetric electronic structures are achieved with strong electronic interactions between these Co species. The Co clusters optimize the adsorption/desorption strength of oxygenated intermediates on single-atomic Co sites to endow exceptional activity under alkaline conditions with a half-wave potential ( E 1/2 ) of 0.91 V and an overpotential (η) of 340 mV at 10 mA cm –2 . In addition, a zinc–air battery assembled with Co SA+C /NC achieves a high power density of 284.1 mW cm –2 and a long operational lifespan of 400 h, superior to those of the benchmark Pt/C + RuO 2 . Experimental findings and theoretical analysis reveal that the enhanced bifunctional activity stems from the synergistic interactions between Co clusters and single-atomic Co sites. Consequently, the overbinding of *OH is suppressed with accelerated *OH removal. This work establishes the design principle of advanced electrocatalysts with multiphase metal species bearing strong electronic interactions.