Cobalt and nitrogen co-doping of porous carbon nanosphere as highly effective catalysts for oxygen reduction reaction and Zn-air battery

Abstract

Nonprecious-doped carbon materials are desirable as appropriate subsititutes for Pt-based catalysts in oxygen reduction reactions and metal-air batteries, but these materials currently present massive challenges due to their sluggish performance and insufficient stability. Herein, a straightforward synthesis strategy of embedding Co in porous carbon nanospheres is reported. Because of the rigid porous spherical structure and the existence of Co-Nx active sites, the as-prepared cathode catalyst exhibits an outstanding oxygen reduction performance (with an onset potential Eonset of 1.03 V vs RHE and a half-wave potential E1/2 of 0.93 V vs RHE) in 0.1 M KOH, outperforming that of commercial Pt/C (Eonset = 1.03 V and E1/2 = 0.87 V), and shows more rapid kinetics. Significantly, the nanomaterial shows a negligible degradation (ΔE1/2 = 4 mV) after 5000 continuous cycles, which surpasses that of most of the highly active electrocatalysts reported to date. In addition, an assembled Zn-air battery composed of this effective electrocatalysts exhibits higher open-circuit voltage (1.44 V), power density (109.5 mW cm−2), and discharge specific capacity (657.2 mA h g−1) as a primary battery and has a long cycle life as a rechargeable battery. This work provides a large-scale preparation route for synthesizing efficient electrocatalysts to drive the oxygen reduction reaction in Zn-air batteries.