Tailoring the synergetic effect of CoN center and sulfur heteroatomic in co-doped carbon electrocatalyst for high performance rechargeable ZnO2 batteries

The trade-off between activity and durability of the oxygen redox reaction (OER and ORR) catalysts, caused by sluggish kinetics and distinct reaction requirements, seriously hinders the application of rechargeable Zn O 2 batteries. Although precious metal catalysts show high activity, they are constrained by cost. Transition-metal catalysts are promising alternatives, but their strong adsorption of oxygen intermediates leads to high reaction energy barriers. Herein, we developed a Co N,SC catalyst (with S atoms doped in the second coordination layer of Co N sites) via coordination reactions and ball milling method. The Co N,SC electrocatalyst exhibits excellent bifunctional performance, with a low potential difference of 0.63 V between the E 1/2(ORR) and the OER overpotential. More importantly, the homemade Zn O 2 battery has a high discharge peak power density of 265.82 mW · cm −2 , a specific capacity of 792.18 mAh · g Zn −1 , and excellent charge-discharge stability with highly reversible energy conversion efficiency. DFT calculations indicate doping with S can enhance the conductivity of the catalysts, adjust the state electron density of the Co N site, and make the d-band center of the Co 3d orbital move down. Therefore, the adsorption energy barriers of the Co N sites to the rate-determining step (O 2  → *OOH in ORR; *OH → *O in OER) are significantly reduced, thus promoting the oxygen redox catalysis reaction kinetics. Our findings open new opportunities for the rational design of non-noble metal catalysts to enhance ORR and OER performance and further improve Zn O 2 battery activities.