In-situ boron and nitrogen doping in flue gas derived carbon materials for enhanced oxygen reduction reaction

Abstract

A model flue gas of N2 and CO2 mixture was directly converted into ‘boron and nitrogen co-doped porous carbon materials (FlueBNPC)’ at 500 °C and atmospheric pressure. The synthesized FlueBNPC showed enhanced electrocatalytic performance for oxygen reduction reaction (ORR) in the fuel cell cathode. Boron and nitrogen in the carbon network, which were simultaneously doped from flue gas in a single step, interplayed as active sites for the electrochemical reaction. The FlueBNPC showed higher electrocatalytic activity than previous heteroatom-doped carbon materials and comparable activity to that of a commercial Pt/C catalyst with a dominant four-electron transfer pathway. This enhancement originates from the newly formed BN bonding combined with oxygen atoms in the carbon network. The synergetic effect of nitrogen attachment to the boron centre of the OBC bonds was investigated by DFT calculations. Our results indicate that flue gas itself can be used as an effective precursor for the one-step process not only to convert CO2 into useful carbon materials, but also to insert boron and nitrogen atoms into the carbon lattices, and we demonstrate a potential utilization of the flue gas as a carbon source for electrochemial applications