Improvement of the electrocatalytic performance of silicon carbide for oxygen reduction reaction induced by nitrogen doping

Abstract

Replacing the precious metal catalysts with low-cost, efficient and stable catalysts for oxygen reduction reaction (ORR) is necessary to solve the challenge of sluggish reaction kinetics. Commercial SiC and aniline were used as a precursor and nitrogen source to prepare a series of nitrogen-doped SiC electrocatalysts (N-SiC) by a facile pyrolysis method at different temperature (800–1100 °C) under nitrogen atmosphere. Among four N-SiC samples, N-SiC-1000 possesses the highest surface area, uniform nanorod morphology, highest nitrogen content, and positively shifted binding energy. Based on these characteristics, the N-SiC-1000 catalyst demonstrates the best ORR catalytic activity manifested by relatively positive onset potential of 1.01 V, half-wave potential (0.87 V) and highest current density (5.38 mA cm−2 at 0.4 V), which is comparable to that of Pt/C, and has significantly better stability and outstanding methanol tolerance than that of Pt/C. The number of electrons transferred of N-SiC-1000 for ORR process is ∼3.97, indicating a 4-electron reaction pathway. These results show that N-SiC-1000 is a low-cost, efficient and stable ORR catalyst and can be used as a substitute for precious metal catalyst in fuel cells application.