Excellent electrocatalytic performance of rice straw-derived carbon catalysts activated by zinc halides for oxygen reduction reaction

Abstract

Biomass-derived carbon materials have been proved to be a prominent catalysts for oxygen reduction reaction (ORR). The chemical activator used in the preparation process of biomass-derived carbon materials has an important impact on its ORR performance. Exploration of suitable chemical activator has become extremely important. Three zinc halides (ZnF2, ZnBr2, and ZnI2) and ZnCl2 used as the activators for the preparation process of rice straw-derived carbon (SDXNC) were carefully studied for the first time. The surface area, pore volume, doping N content and surface defect of as-prepared SDXNCs were effectively improved with the pyrolysis temperature of 1100 °C, further improving the ORR activity of SDXNC samples. The four rice straw-derived carbons activated by ZnX2 presented high onset potential, half-wave potential and limited current density, which can comparable to those of Pt/C. Moreover, they also occupy the typical 4-electron reduction pathway, ultrahigh methanol tolerance, and durability for ORR. Therefore, a class of low-cost and excellent chemical activators can be used for the preparation of biomass-derived carbon materials with prominent ORR activity.