High-level nitrogen-doped, micro/mesoporous carbon as an efficient metal-free electrocatalyst for the oxygen reduction reaction: optimizing the reaction surface area by a solvent-free mechanochemical method

High-level nitrogen-doped (>10 at%), high-surface-area (>1600 m(2) g(-1)) micro/mesoporous carbon derived from coconut mesocarp was prepared by a solvent-free ball-milling process using melamine as a solid-state nitrogen dopant and potassium bicarbonate as a safe and green activating agent. Synergistic nitrogen doping and pore formation maximize the nitrogen doping concentration/specific surface area/pore volume and minimize the pore blockage. This nitrogen-doped porous carbon exhibits comparable catalytic activity for the oxygen reduction reaction (ORR) to the commercial Pt/C catalyst in terms of the onset potential and the current density and exhibits superior stability and methanol tolerance to the benchmark catalyst, thanks to its optimized reaction surface area.