Molten-Salt-Assisted Synthesis of Nitrogen-Doped Carbon Nanosheets Derived from Biomass Waste of Gingko Shells as Efficient Catalyst for Oxygen Reduction Reaction

Developing superior efficient and durable oxygen reduction reaction (ORR) catalysts is critical for high-performance fuel cells and metal-air batteries. Herein, we successfully prepared a 3D, high-level nitrogen-doped, metal-free (N-pC) electrocatalyst employing urea as a single nitrogen source, NaCl as a fully sealed nanoreactor and gingko shells, a biomass waste, as carbon precursor. Due to the high content of active nitrogen groups, large surface area (1133.8 m(2) g(-1)), and 3D hierarchical porous network structure, the as-prepared N-pC has better ORR electrocatalytic performance than the commercial Pt/C and most metal-free carbon materials in alkaline media. Additionally, when N-pC was used as a catalyst for an air electrode, the Zn-air battery (ZAB) had higher peak power density (223 mW cm(-2)), larger specific-capacity (755 mAh g(-1)) and better rate-capability than the commercial Pt/C-based one, displaying a good application prospect in metal-air batteries.