1,2,4-triazole-assisted metal-organic framework-derived nitrogen-doped carbon nanotubes with encapsulated Co4N particles as bifunctional oxygen electrocatalysts for rechargeable zinc-air batteries

Co4N@NCNTs with superior ORR and OER activity and stability were prepared by triazole -assisted in-situ pyrolysis of MOF-74/TZ. [Display omitted] •Co4N@NCNTs were prepared by triazole -assisted in-situ pyrolysis of MOF-74/TZ.•The possible structure outward contract evolution mechanism of Co4N@NCNTs was investigated.•Co4N@NCNT-900 showed superior ORR and OER catalytic activity and stability.•A ZAB with Co4N@NCNT-900 air cathode delivers higher power density and specific capacity. 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, Co4N particles encapsulated at the top of N-doped carbon nanotubes (Co4N@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 Co4N particles and the highly graphitized N-doped carbon nanotubes (NCNTs), Co4N@NCNTs obtained at 900 °C (Co4N@NCNT-900) exhibited astonishing catalytic performance in both ORR and OER, and high reversible oxygen bifunctional activity (ΔE = 0.685 V). Moreover, Co4N@NCNT-900 displayed a larger discharge power density (122 mW cm−2), a better specific capacity (811.8 mAh g−1), and more excellent durability during the ZAB test, implying that Co4N@NCNT-900 can act as a bifunctional high active catalyst in ZABs.