N, S co-doped carbon film wrapped Co nanoparticles for boosting oxygen reduction reaction

Abstract

Electrochemical energy (e.g., fuel cell and metal-air batteries) is featured by large theoretical energy density, high conversion efficiency, safe operation and pollution-free emission. However, the sluggish dynamics of oxygen reduction reaction (ORR) and high cost of noble metals hinder their widespread commercial applications in electrochemical energy devices. Herein, we present a method for the preparation of the N, S co-doped carbon film wrapped Co nanoparticles (Co/NSC) for ORR by aging and then pyrolyzing the mixture of cobalt salt and 1-(p-Toluenesulfonyl)imidazole. The co-doping of N and S facilitates the electron rearrangement of the carbon film, resulting in a rapid electron transfer. The core-shell structure enhances the interaction between N, S co-doped carbon film and Co nanoparticles. These features endow the Co/NSC catalyst an excellent ORR with a half-wave potential of 0.860 V and limiting current density of 6.2 mA cm-2, besides the superior anti-methanol. The Co/NSC catalyst as the air cathode grants the assembled zinc-air battery high open circuit voltage (1.467 V), large peak power density (156.2 mW cm-2), great specific capacity (747.9 mAh gZn-1), and excellent stability. Thus, the prepared Co/NSC catalyst exhibits a promising application in zinc-air battery. This work provides an approach for the synthesis of the carbon-shell coated non-noble metal catalyst and its subsequent applications in oxygen electrocatalysis.