Highly-active, metal-free, carbon-based ORR cathode for efficient organics removal and electricity generation in a PFC system

Abstract

A highly-active, metal-free, carbon-based oxygen reduction reaction (ORR) cathode, i.e., graphitized N-doped carbon felt (GNCF), was prepared, for the first time, by in-situ modifying the doping species of polyacrylonitrile (PAN)-based carbon felt (CF) via a facile annealing process in Ar atmosphere. It was applied for dramatically enhanced organics degradation and electricity generation in a photocatalytic fuel cell (PFC) system. The GNCF showed enhanced specific surface area, improved graphitization and raised ratio of graphitic N, therefore resulting in excellently improved ORR performance compared to the CF. When applying the GNCF as a cathode in a PFC system, the proposed PFC showed significant improvement in degrading various model organic contaminants and outputing electricity simultaneously when compared with the PFC with CF. For instance, the apparent rate constant and electricity output efficiency showed ∼10.6 times and ∼7.2 times, respectively, improvement when using rhodamine B as model waste. Further improved performance was also achieved by aeration of air or O2 due to the further enhanced ORR. The proposed PFC was also efficient in a wide pH, and kept outstanding stability in long-term utilization.