Abstract
Reducing the oxygen adsorption energy barrier is vital to accelerate the oxygen reduction reaction (ORR). Herein, we report a mesoporous cake-like structured Zn-N/Cu-N electrocatalyst (ZnCu-N-C) with robust electrocatalytic performance and exceptional durability in 0.1 M KOH solution. The mesoporous cake-like structure is promising to expose more active sites. Extended X-ray absorption fine spectroscopy and X-ray photoelectron spectroscopy confirmed the existence of M-Nx (M = Zn, Cu). More importantly, the density functional theory (DFT) calculations corroborate that the Zn-N/Cu-N dual active center can reduce the oxygen adsorption energy barrier. Therefore, the optimized ZnCu-N-C electrocatalyst is ahead of commercial Pt/C (20 wt%) in all aspects. Moreover, the ZnCu-N-C-based Zn–air batteries exhibit outstanding long-term stability of 240 cycles, a large power density of 156.2 mW cm−2, and a high specific capacity of 732.7 mA h g−1. This work may provide new guidance for the rational design of cathode catalysts in Zn-air batteries.
The mesoporous cake-like co-doped with zinc, copper and nitrogen are constructed by pyrolyzing the ZnCu-MOFs precursors as an effective ORR electrocatalyst for advanced Zn–air batteries. The robust electrocatalytic activity is attributed to the Zn-N/Cu-N pair active center that reduces the oxygen adsorption energy barrier, and the mesoporous structure promotes rapid mass transfer. [Display omitted]
•ZnCu-N-C catalyst with pair active sites was constructed by high-temperature pyrolysis of ZnCu-ZIF.•The catalyst exhibits robust ORR activity outperformed Pt/C in alkaline media.•The ZnCu-N-C catalyst exceeds state-of-the-art Pt/C in practical Zn-air battery.•DFT calculations and EXAFS provided profoundly insight about high ORR activity.