Zinc chloride-activated micro-mesoporous carbon material derived from energy grass and its electrocatalytic performance toward oxygen reduction reaction

Abstract

Biomass is an ideal candidate for the preparation of nano-carbon catalyst because of its inherent porous structure and abundant heteroatoms. However, the rational design of the structure remains challenging. In this work, a biomass-based carbon material with micro‑meso porous structure, high specific surface area and abundant active sites was fabricated by the activation of ZnCl2. The correct additive amount of activator is essential to affect the surface composition and structures. In order to achieve a high-performance carbon catalyst, the activation mechanism of ZnCl2 for the pyrolysis of elephant grass (EG) was also investigated. The electrochemical measurements revealed that the obtained carbon catalyst with an EG:ZnCl2 ratio of 1:1 showed superior electrocatalytic properties for ORR over a wide pH range, due to the its large surface area (1119.83 m2g−1), hierarchical structure and abundant N content (pyridine-N/graphite-N/pyrrolic-N). The abundant micro/mesoporous structure provides accessible channels for the transport of O2, H2O and intermediate products (OH*, O2*). This study provides a simple and low-cost method for the effective conversion of biomass to nano-carbon materials, which shows great application potential for fuel cells.