Self-catalyzed growth of Zn/Co-N-C carbon nanotubes derived from metal-organic frameworks as efficient oxygen reduction catalysts for Zn-air battery

Abstract

Designing cost-effective and high-performance carbon-based oxygen reduction reaction (ORR) electrocatalysts is crucial in the development of Zn-air batteries (ZABs). In this study, a facile one-pot synthesis approach is engineered to construct Zn/Co-N-C carbonaceous polyhedrons interconnected with self-catalyzed-grown carbon nanotubes (CNTs) from zeolitic imidazolium frameworks linked with graphene oxide nanosheets. The special N-doped three-dimensional (3D) carbon matrix allows manipulating the exposure of active sites and the synergistic interaction between metal nanoparticles and CNTs. The as-synthesized catalyst features impressive ORR activity in 0.1 mol L−1 KOH (E1/2 = 0.83 V) and 0.5 mol L−1 H2SO4 (E1/2 = 0.73 V), satisfactory cycling stability and methanol resistance comparable to those of the benchmark Pt/C catalyst (E1/2 = 0.80 V in 0.1 mol L−1 KOH, E1/2 = 0.75 V in 0.5 mol L−1 H2SO4). Furthermore, the as-established ZAB demonstrates a competitive peak power density (90 mW cm−2) and prominent long-term stability, which are better than those of devices based on the commercial Pt/C catalyst (82 mW cm−2). This work provides promising guidance for fabricating highly effective ORR catalysts with in situ formed CNTs, which can be applied in portable ZAB-related devices.