Electrocatalytic Activity of Heteroatom-Doped Graphene for Oxidation of Hydroquinones

In the present study, we aim to synthesize heteroatom (nitrogen or boron) doped-reduced graphene oxide (N-rGO or B-rGO) as a catalyst for the electro-oxidation of hydroquinones, used as a candidate of fuel (hydrogen carrier molecule) for direct-type fuel cells (DFC5), and evaluate the doping effect on its catalytic activity. N-rGO and B-rGO were prepared from a mixture of graphene oxide (GO) and urea or boron trioxide by pyrolysis method. We characterized the morphology and crystal structure of the prepared materials by transmission electron microscopy, and X-ray diffraction, respectively. Energy dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy show the loading amount of the heteroatoms, 10.4wt% N and 2.9 wt% B, as well as their chemical nature. The electrochemical analysis of the prepared materials by rotating disk electrode system reveals high activity of B-rGO, 15 and 85 mV lower overvoltage compared with rGO at the half-wave potential of diffusion-limited current, for the electro-oxidation of hydroquinone and methyl-hydroquinone, respectively, because of its electron-accepting nature. We demonstrate that thus modified carbons exhibit high activity, B-rGO > N-rGO > rGO, for the oxidation of hydroquinone derivatives as non-metallic anodes of DFC5. (C) The Author(s) 2020. Published by ECSJ.