posted on 2024-02-09, 17:11authored byHui-Min Xu, Hong-Rui Zhu, Zhi-Jie Zhang, Chen-Jin Huang, Ting-Yu Shuai, Qi-Ni Zhan, Gao-Ren Li
A long-term goal of rechargeable zinc–air batteries
(ZABs)
has always been to design bifunctional electrocatalysts that are robust,
effective, and affordable for the oxygen reduction reaction (ORR)
and oxygen evolution reaction (OER). It has become a feasible method
to construct metal/metal oxide interfaces to achieve superior electrocatalytic
performance for ORR and OER by enhanced charge transfer. In this study,
Co/Co3O4 heterojunctions were successfully prepared
and encased in porous N-doped mesoporous carbon (Co/Co3O4@NC) via a simple condensation-carbonization-etching
method. The extensive specific surface area of Co/Co3O4@NC facilitates effective interaction between the electrolyte
and the catalyst, thereby enabling sufficient exposure of active sites
for the ORR and the OER, consequently enhancing the rate of transport
of active species. The well-designed Co/Co3O4@NC delivers superior ORR catalytic activity with a half-wave potential
of 0.82 V (vs RHE) and a low overpotential of 347 mV at 10 mA cm–2 for OER in alkaline solution. The power density of
Co/Co3O4@NC-based alkaline aqueous ZAB (156.5
mW cm–2) is superior to the commercial Pt/C + IrO2-based alkaline aqueous ZAB, and the cycling stability of
ZAB is up to 220 h. In addition, Co/Co3O4@NC-based
ZAB shows a high power density (50.1 mW cm–2). The
construction of metal/metal oxide heterojunction encased in N-doped
mesoporous carbon provides a novel route for the design of bifunctional
electrocatalysts for high-performance ZABs.