Solvent-free synthesis of honeycomb-like N-doped porous carbon derived from biomass pine sawdust as an efficient metal-free electrocatalyst for oxygen reduction reaction

Nitrogen-doped carbon material is a promising oxygen reduction reaction (ORR) catalyst with great potential as a substitute for Pt-based electrocatalysts in fuel cells. Herein, N-doped porous carbon (N-PC) with a honeycomb-like structure was prepared by a simple solvent-free ball-milling method, in which the mixtures of waste biomass pine sawdust, melamine and K2CO3 were thermally annealed at 900 °C. The prepared N-PC catalyst exhibited a huge specific surface area (1504 m2/g), and a high N content (7.6 wt%). Comparable onset potential (0.96 V vs RHE) and half-wave potential (0.84 V vs RHE) to that of commercial Pt/C catalyst were achieved. Moreover, the N-PC demonstrated superior durability and methanol tolerance. The excellent catalytic performances of N-PC were correlated with the integrated effects of porous structure, large specific surface area, rich active sites, high defect level and great electrical conductivity. It provides an alternative way to construct metal-free materials as ORR electrocatalysts.