Catalytic synthesis and simultaneous co-doping of hierarchically porous carbon with in-situ coated graphene from biomass tar as efficient catalyst for ORR

Although oxygen reduction reaction (ORR) plays a key role in the cathodic part of many emerging energy conversion devices, it has naturally suffered from sluggish kinetics and high overpotential. We here report the facile synthesis of Fe-N co-doped carbon with a hierarchical porosity and in-situ formed graphene from biomass tar using urea as the nitrogen dopant, and FeCl3 as the porogen, catalyst, and Fe dopant. This exhibited an ORR catalytic activity comparable to that of a Pt/C catalyst in relation to its onset potential, limited diffusion current, and stability under an alkaline condition. It was found that the excellent catalytic performance should have originated from its large specific surface area, abundant active centers, and long-term conductive network. This renewable non-noble-metal catalyst may serve as an appropriate alternative to conventional noble catalysts in ORR-based techniques, and will also encourage investigations on the use of biomass tar for advanced materials toward various ends.