Accelerating electron transport in Eosin Y by bidentately bridging on BaSnO3 for noble-metal-free photocatalytic H2 production

The separation and transport of photogenerated carriers is regarded as a curial factor in photocatalytic H₂ production. As known in solar cells and photoelectron-chemistry, to strengthen the electron conduction for effective utilization of carriers, the electron transport material (ETM) is widely applied. Herein, inspired by the function of ETM, we adopted barium stannate (BaSnO₃, labeled as BSO) as an excellent ETM which had the merits of high electron mobility, suitable conduction band position and simple preparation, to adjust the carrier kinetics of dye Eosin Y (EY)-sensitized photocatalytic system. Detailly, the photocatalytic system with the spatial separation sites of photogenerated carriers excitation and water reduction reaction was elaborately constructed, that was, dye EY-sensitized BSO (EY/BSO) for photocatalytic H₂ production. The photocatalytic H₂-production rate of EY/BSO (257 μmol·h⁻¹·g_EY⁻¹) in the absence of noble metals was 28.6 times higher than that of single EY (∼9 μmol·h⁻¹·g_EY⁻¹) under visible-light irradiation. With systematic and comprehensive characterizations, the formed electron transport channel by the bidentate bridging of EY on BSO could accelerate the transfer of photogenerated electrons from EY to BSO, promoting the effective separation of photogenerated carriers for the enhanced photocatalytic performance. Moreover, the water reduction reaction for H₂ production proceeded on the surface of BSO that acted as the H₂-evolution cocatalyst, avoiding the use of high-cost noble metals. Furthermore, based on the well-proved ETM-based concept in the EY/BSO system, La-doped BaSnO₃ (LBSO) with better electron transport ability was adopted to construct EY/LBSO system (344 μmol·h⁻¹·g_EY⁻¹) which showed better photocatalytic activity than EY/BSO.