Preparation and oxygen reduction performance of nitrogen-doped cotton stalk-derived carbon

Abstract

Oxygen reduction reaction (ORR) is a key step in the operation of fuel cells and metal air cells, which needs some economic and efficient catalysts to improve its reaction kinetics process. In this work, nitrogen-doped carbon (N-C) catalyst material was prepared by one-step high-temperature pyrolysis with biomass waste cotton stalk as carbon/nitrogen precursor material and urea as auxiliary nitrogen source. The effect of temperature on the structure and performance of the prepared N-C catalyst was investigated. The experimental results show that a small temperature change of 25°C will cause a significant change in the structure of N-C material. N-C-900 samples prepared at 900°C had a larger specific surface area of 620 m2 g-1, significantly improved graphitization degree and nitrogen content (7.30 at%) and showed significantly better ORR performance than other samples in alkaline medium. The ORR activity of N-C-900 sample is the best, indicated by the highest Eonset (0.92 V) and E1/2 (0.85 V) of ORR, which are positively shifted by 20 and 30 mV compared with commercial Pt/C. Its ORR initial potential and half-wave potential are similar to those of commercial Pt/C, and it shows better ORR stability and methanol resistance than Pt/C.