Synchronous bi-modulation by nanoclusters and single atoms for high-efficient oxygen reduction electrocatalysis

Developing single-atom catalysts with robust performance for oxygen reduction reaction (ORR) is of paramount importance, whereas their unsatisfactory intrinsic activity remains a significant challenge. Herein, density functional theory simulation indicates that the synchronous bi-modulation by Co nanoclusters and Zn single atoms (ZnN4) can increase Co active centers' electron density, thus improving the intrinsic activity of Co single-atom (CoN4) sites. Inspired by these findings, a multiscale catalyst with highly-dispersed Co/Zn metal atoms and nanoclusters anchored on a porous N-doped carbon skeleton has been successfully synthesized. The resultant Co1/Zn20-N-C-200 exhibits remarkable ORR performance with a positive half-wave potential (E1/2 = 0.89 V), outstanding methanol tolerance, and superior stability in alkaline media, outperforming a majority of nonprecious metal-based catalysts and the benchmark Pt/C catalyst in some aspects. Co1/Zn20-N-C-200 also achieves high open-circuit voltage of 1.47 V and power density of 116 mW cm−2 when applied in the self-made Zn-air battery.