Zhenjiang Li, Xuehua Wang, Jing Liu, Chenghai Gao, Luhua Jiang, Yusheng Lin, and Alan Meng*

ABSTRACT

The development of high-efficiency non-noble metal catalysts for the oxygen reduction reaction (ORR) is of paramount significance to sustainable energy-conversion technologies. Herein, a three-dimensional (3D) honeycomb nanostructure comprised of mesoporous N-doped carbon nanosheets encapsulating isolated cobalt and vanadium nitride nanoparticles (denoted Co−VN−NC) is synthesized through a facile one-step pyrolysis method. The catalyst prepared under optimal temperature exhibits excellent ORR performance with an Eonset of 0.032 V and an E1/2 of −0.086 V (vs Ag/AgCl) in 0.1 M KOH solution, which is very close to that of commercial 20% Pt/C, and it also shows better ORR performance in 0.5 M H2SO4 solution. Moreover, it demonstrates a superior enhanced tolerance to methanol poisoning compared with that of Pt/C. More importantly, the optimized catalyst shows extraordinary stability with a little current decline of less than 4 and 8% during chronoamperometric evaluation for more than 30 000 s in alkaline and acidic solutions, respectively. It has been proved that the catalyst favors an efficient four-electron pathway-dominated ORR process. The excellent performance can be ascribed to the 3D honeycomb nanostructure with a number of mesopores, which possesses high specific surface area (433.20 m2 g−1) conducive to the high exposure level of the active sites, the efficient electron-transfer capability between different metal nanoparticles, and a powerful protective effect of the N-doped carbon layer. This work not only provides great potential non-noble metal ORR electrocatalysts comparable to Pt/C but also puts forward a simple and scalable pyrolysis method to prepare nonprecious metal catalysts.

DOI: 10.1021/acssuschemeng.9b06934