Synergistic modulation via SnO2 seed layer and Bi2S3/Bi2WO6 heterojunction toward enhanced H2 evolution and electricity generation in photocatalytic fuel cell

To optimize the photoexcited charge carrier transport kinetics at the interface between the FTO substrate and the photocatalyst, this study systematically investigates the impact of SnO 2 and TiO 2 charge transport layers on the photocatalytic efficiency of the photoanode. Density functional theory computations reveal that the SnO 2 charge transport layer possesses superior electron transport properties compared to the TiO 2 . The as-prepared SnO 2 pre-Bi 2 S 3 /Bi 2 WO 6 photoanode exhibits broad visible-light absorption and outstanding photoelectrochemical performance, showing a photocurrent density of 5.12 mA cm −2 for the optimized SnO 2 pre-Bi 2 S 3 /Bi 2 WO 6 -2, which is ∼7 and 82.5 times higher in comparison to that of the SnO 2 pre-Bi 2 WO 6 (0.732 mA cm −2 ) and pure Bi 2 WO 6 photoanode (0.062 mA cm −2 ), respectively. Obviously, the SnO 2 charge transport layer and Bi 2 S 3 /Bi 2 WO 6 heterojunction formation substantially increase the separation efficiency of photoinduced charges and optimize the transport pathways. Herein, a dual-photoelectrode PFC system was established utilizing a SnO 2 pre-Bi 2 S 3 /Bi 2 WO 6 photoanode and a Cu 2 O/Cu photocathode. Moreover, the proposed PFC shows outstanding hydrogen production and electricity generation performance, achieving a hydrogen yield of 37.2 μmol cm −2 h −1 and power density of 0.0431 mW cm −2 . The system maintains stable performance over five consecutive cycles.