LAUSR

The development of nonprecious metal catalysts with both oxygen reduction and evolution reactions (ORR/OER) is very important for Zn-air batteries (ZABs). Herein, a Co5.47 N particles and Fe single atoms co-doped hollow carbon nanofiber self-supporting membrane (H-CoFe@NCNF) is synthesized by a coaxial electrospinning strategy combined with pyrolysis. X-ray absorption fine spectroscopy analyses confirm the state of the cobalt nitride and Fe single atoms. As a result, H-CoFe@NCNF exhibits a superior bifunctional performance of Eonset  = 0.96 V for ORR, and Ej = 10 = 1.68 V for OER. Density functional theory calculations show that H-CoFe@NCNF has a moderate binding strength to oxygen due to the coexistence of nanoparticle and single atoms. Meanwhile, the Co site is more favorable to the OER, while the Fe site facilitates the ORR, and the proton and charge transfer between N and metal atoms further lower the reaction barriers. The liquid ZAB composed of H-CoFe@NCNF has a charge-discharge performance of ≈1100 h and a peak power density of 205 mW cm-2 . The quasi-solid-state ZAB assembled by the self-supporting membrane of H-CoFe@NCNF is proven to operate stably in any bending condition.