Bifunctional Electrocatalytic Activity of Boron-Doped Graphene Derived from Boron Carbide

A single material that can perform water oxidation and oxygen reduction reactions (ORR), also called bifunctional catalyst, represents a novel concept that emerged from recent materials research and that has led to applications in new-generation energy-storage systems, such as regenerative fuel cells. Here, metal/metal-oxide free, doped graphene derived from rhombohedral boron carbide (B₄C) is demonstrated to be an effective bifunctional catalyst for the first time. B₄C, one of the hardest materials in nature next to diamond and cubic boron nitride, is converted and separated in bulk to form heteroatom (boron, B) doped graphene (BG, yield ≈7% by weight, after the first cycle). This structural conversion of B₄C to graphene is accompanied by in situ boron doping and results in the formation of an electrochemically active material from a non-electrochemically active material, broadening its potential for application in various energy-related technologies. The electrocatalytic efficacy of BG is studied using various voltammetric techniques. The results show a four-electron transfer mechanism as well as a high methanol tolerance and stability towards ORR. The results are comparable to those from commercial 20 wt% Pt/C in terms of performance. Furthermore, the bifunctionality of the BG is also demonstrated by its performance in water oxidation.