Self-templating synthesis nitrogen and sulfur co-doped hierarchical porous carbons derived from crab shells as a high-performance metal-free oxygen electroreduction catalyst

Abstract Heteroatom-doped carbon materials with high activity, chemical stability and low cost, as promising metal-free electrocatalyst candidates to replace commercial Pt/C catalysts stand for the main challenge precluding their practical applications and commercialization in oxygen reduction reactions (ORR) of metal–air batteries and fuel cells. Here, we report a green and scalable fabrication of hierarchical porous carbons with honeycomb-like structure as a high-performance metal-free catalyst toward ORR, via one-step pyrolysis of crab shells. The nitrogen and sulfur co-doped carbons with a morphology containing macro-, micro-, and mesopores were obtained, avoiding the use of template agent and activated process. The pyrolysis temperature of crab shells played a critical role in the heteroatom content, pore structure and active site as well as electro catalytic performance of the resulting carbon catalyst. The optimal carbon catalyst pyrolyzed at 900 °C exhibits excellent ORR activity with an onset potential of 0.072 V and a half-potential of −0.110 V (vs. Ag/AgCl) in alkaline electrolytes, and superior methanol tolerance durability to the commercial Pt/C. Our as-obtained carbons will certainly be expected to open a trend setter and generate substantial economic values by creating value-added materials from waste.