Efficient hydrogen production and electricity generation in solar-driven single-photoelectrode photocatalytic fuel cell

This work reports a novel TiO₂/g-C3N4 photoanode-based photocatalytic fuel cell (PFC) designed to convert chemical energy from simulated wastewater. The g-C3N4 modified TiO₂ nanorod was successfully synthesized by a facile hydrothermal method. The results indicated that the maximum photocurrent density reached 2.44 mA cm^-2 at 1.23 V vs. RHE by 1.167 g L^-1 g-C3N4 loaded TiO₂ composite. On the basis of analysis, the photoelectrochemical mechanism of the composite photoanode was proposed. This mainly demonstrated that the composite photoanode increases the electron donor density and boosts charge separation efficiency. In addition, the power density and hydrogen production of the proposed PFC were enhanced by 5.37 and 1.49 times compared to TiO₂ photoanode-based PFC. To find the origins of the excellent performance of PFC, the influence of the organic compounds were investigated. The ESR measurement results indicated that the organic matter was captured by the photoexcited holes directly to facilitate the charge separation. The achieved power density and hydrogen production of 0.14 mW cm^-2 and 21.60 μmol h^-1 cm^-2 were measured using RhB as the model pollutant, which was 2.42 and 1.23 times higher than the experiments with PBS electrolyte. This study proposed a novel PFC system converts the organic pollutant to the hydrogen and the electricity.