Microwave-hydrothermal synthesis of boron/nitrogen co-doped graphene as an efficient metal-free electrocatalyst for oxygen reduction reaction

In this study, a facile microwave-hydrothermal method was successfully applied to synthesize boron and nitrogen co-doped graphene (BNG) electrocatalyst for the oxygen reduction reaction (ORR). It consists of an efficient two-step process involving simultaneous doping with different heteroatoms (B and N) and reduction of doped graphene oxide. It was found that the B and N contents of highly reduced BN co-doped graphene (HRBNG) are 3.55 and 4.43 at%, respectively. The HRBNG exhibited clearly enhanced electrocatalytic activity towards the ORR in alkaline electrolytes. The electron transfer number (n) was obtained 3.53 ∼ 3.84 in potential range of 0.465 V-0.225 V, indicating that the HRBNG favors the four-electron pathway for the reduction of oxygen. These results demonstrate that the synthesized HRBNG has potential to replace expensive precious metal catalysts and also provide a new strategy to synthesize heteroatom-doped graphene-based catalyst.