1,2,4-triazole-assisted metal-organic framework-derived nitrogen-doped carbon nanotubes with encapsulated Co 4 N particles as bifunctional oxygen electrocatalysts for rechargeable zinc-air batteries

The design of high-performance oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) dual-functional catalysts is not only important for the further applications of zinc-air batteries (ZABs) but also a major challenge in the field of energy conversion. The cheap 1,2,4-triazole (1,2,4-TZ) can be decomposed easily by heat, making it a high research value in carbon catalysts derived from metal-organic frameworks (MOFs). Here, Co N particles encapsulated at the top of N-doped carbon nanotubes (Co N@NCNTs) were conveniently prepared by 1,2,4-TZ-assisted pyrolysis of Co-MOF-74 for the first time. Owing to the excellent activity of Co N particles and the highly graphitized N-doped carbon nanotubes (NCNTs), Co N@NCNTs obtained at 900 °C (Co N@NCNT-900) exhibited astonishing catalytic performance in both ORR and OER, and high reversible oxygen bifunctional activity (ΔE = 0.685 V). Moreover, Co N@NCNT-900 displayed a larger discharge power density (122 mW cm ), a better specific capacity (811.8 mAh g ), and more excellent durability during the ZAB test, implying that Co N@NCNT-900 can act as a bifunctional high active catalyst in ZABs.