Remarkable upgrade of hydrogen evolution activity up to 40.8 folds and mechanistic investigation of expediting charge transfer achieved by Bi2O3-modified TiO2 photocatalyst

Abstract

Targeting on significantly promoting the hydrogen generation activity of titanium dioxide-based photocatalysts without the modification of noble metals by a straightforward synthetic strategy, simultaneously unveiling the photocatalytic mechanism of expedited charge transfer in photocatalyst are necessary but remains challenging. In this work, Bi2O3-modified TiO2 nanocomposite materials were directly synthesized via employing a solid-state synthesis method at mild conditions. The Bi2O3–modified TiO2 photocatalyst enable to achieve a remarkable hydrogen generation rate, dramatically outperforming commercial titanium oxide by 40.8 times. Photoelectric measurements were well matched with the broaden light absorption range and expedited charge transfer in photocatalyst, which are primarily responsible for the high-performance photocatalytic hydrogen evolution. The partially formed metallic Bi serves as a mediator between Bi2O3 and commercial TiO2 to facilitate photoexcited carriers’ separation and migration. The density functional theory simulations were further executed to calculate the differential charge distribution. It successfully unveils the electron transferring property (0.97 e−) in photocatalysts during photocatalytic process, which is well-matched with experiments derived from photoelectric measurements and uncovers the underlying photocatalytic mechanism. This work offers an efficient strategy for modifying the TiO2-based photocatalysts and dramatically achieving high-performance photocatalytic hydrogen evolution activity.