MOF-derived nitrogen-doped carbon-based trimetallic bifunctional catalysts for rechargeable zinc-air batteries

Zinc-air battery (ZAB) is a promising new metal-air energy system, but the large overpotentials of oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) around the air electrode lead to their poor energy efficiency. Herein, a novel bifunctional oxygen electrocatalyst is reported with the preparation of a zeolite imidazolate framework (ZIF-67) derived trimetallic composites decorated nitrogen-doped carbon, which consist of NiFe alloy and Co nanoparticles. The ZIF-derived porous N-doped carbon shell can speed up the mass transfer efficiency. Whereas the electronic effect between the formed NiFe alloy and Co nanoparticles, as well as the N-doped carbon framework can enrich the active centers and enhance the electrical conductivity. As a result, the NiFe-Co@NC-450 catalyst shows superior performance manifested as a small potential gap (Delta E = 0.857 V) between the overpotential at 10 mA cm(-2) (E (j=10)) for OER (460 mV) and half-wave potential (E (1/2)) for ORR (0.833 V). The liquid ZABs exhibit a high specific capacity reaching 798 mAh/g(Zn) and a stable cycling performance at 10 mA cm(-2) for more than 200 h. Meanwhile, the NiFe-Co@NC-450 based flexible ZABs also presents robust flexibility and stability. This study has certain implications for the development of economical, powerful and stable bifunctional catalysts for ZABs.

Automated summary

In this study, a novel bifunctional oxygen electrocatalyst based on ZIF-67 derived trimetallic composites decorated nitrogen-doped carbon was reported, showing superior catalytic performance and stability, which has potential implications for the development of economical, powerful and stable ZABs.