Porous N,P-doped carbon from coconut shells with high electrocatalytic activity for oxygen reduction: Alternative to Pt-C for alkaline fuel cells

Abstract

This study introduces a new, environmentally-friendly method to synthesize N,P-doped porous carbon by high conversion (46% yield) of coconut shell residues for the reduction of oxygen in alkaline media. The obtained materials display an excellent electrocatalytic activity, making them suitable as cathode catalyst for alkaline fuel cells. The synthesis procedure included an efficient single-step activation with phosphoric acid to achieve high surface area (1216m2g−1) and pore volume (1.15cm3g−1 with 72% mesopores). Urea was used as a low-cost and ecologically-sound source for nitrogen doping of the as-synthesized porous carbon. Remarkably, the biomass-derived electroactive carbon demonstrates a superior performance compared to a reference material, the state-of-the-art commercial Pt-C catalyst: (a) comparable electrocatalytic activity; (b) better tolerance to methanol crossover effects and, (c) improved long-term durability towards oxygen reduction reaction in alkaline media.