Boron and nitrogen codoped nanodiamond as an efficient metal-free catalyst for oxygen reduction reaction

Developing highly active metal-free oxygen reduction reaction (ORR) catalysts with strong durability is crucial for a variety of renewable energy applications including fuel cells and metal-air batteries. Herein, we synthesized boron and nitrogen codoped nanodiamond (BND) as a highly efficient metal-free catalyst for ORR under alkaline conditions. X-ray photoelectron spectroscopy (XPS) demonstrated that B and N atoms have been incorporated in the diamond. The resultant BND was found to be advantageous over N- or B-doped diamond for ORR in terms of current density and peak potential, highlighting the synergetic effects of codoping with B and N. Meanwhile, BND outperformed the commercial Pt/C catalyst in terms of kinetic current density, stability, and methanol tolerance. The zinc-air battery with BND as air cathode catalyst showed higher power density (at current density above 18.0 mA cm-2) and better rechargeability than those with a commercial Pt/C catalyst.