Catalytic Effects of B/N-co-Doped Porous Carbon Incorporated with Ketjenblack Nanoparticles for All-Vanadium Redox Flow Batteries

Heteroatom-doping in carbon structures plays a key role in the catalytic activities. We report bio-derived porous carbon catalysts by a self-contained nitrogen in orange peels with additional boron co-doping. This heteroatom co-doped porous carbon materials are coated with the ketjenblack nanoparticles (KB-BNPC) to increase electrical conductivity. We newly discover that the KB-BNPC electrocatalyst increases electrocatalytic activities toward vanadium redox couples of V 2+ /V 3+ and VO 2 + /VO 2+ , demonstrating the improvement of redox onset potentials and peak currents. Notably, we control the doping ratio of B and N atoms, suggesting that B/N ratio of 0.65 gives rise to a synergistic effect of the heteroatoms for vanadium redox reactions. We believe that the optimized porous structures and defects in the KB-BNPC catalyst can facilitate the absorption and desorption of the vanadium ions by enhancing electron and mass transfer kinetics.