Oxygen vacancy-rich N-doped carbon encapsulated BiOCl-CNTs heterostructures as robust electrocatalyst synergistically promote oxygen reduction and Zn-air batteries

The development of non-precious metal catalysts for oxygen reduction reactions (ORR) is vital for promising clean energy technologies such as fuel cells, and zinc-air batteries. Herein, we present a stepwise synthesis of N -doped and carbon encapsulated BiOCl-CNTs heterostructures. Electrocatalytic ORR studies show that the optimized catalyst has a high half-wave potential (E 1/2 ) of 0.85 V (vs. RHE), large limiting current density (-5.34 mA cm −2 @0.6 V) in alkaline medium, and nearly perfect 4 e − reduction characteristics, even surpassing commercial Pt/C. Meanwhile, the catalyst has exceptional durability (above 97.5 % after 40000 s) and strong resistance towards methanol poisoning. The good ORR activity also results in high-performance zinc-air batteries with a specific capacity (724 mAh g −1 @10 mA cm −2 ), a high open-circuit potential of 1.51 V and a peak power density of 170.7 mW cm −2 , as well as an ultra-long charge–discharge cycle stability (155 h), comparable with the Pt/C catalyst. The catalytic mechanism reveals that the excellent electrocatalytic performance originates from the synergistic effect of N doping, oxygen vacancies, and BiOCl sites.