Strain-Induced Photocatalytic H₂ Production over BiVO₄ in Pure Water without Any Cocatalyst

In this study, BiVO₄ nanosheets (BiVO₄-NS) were prepared by a facile hydrothermal method. It is found that sonication-induced strain can effectively promote the H₂ production over BiVO₄-NS in the presence of pure water without any cocatalysts. With the assistance of the sonication, the H₂ production over BiVO₄-NS is 1.344 mmol·g^-1 after 3 h simulated sunlight irradiation, which is 24.8 times higher than that of BiVO₄-NS without sonication (0.054 mmol·g^-1). In addition, the products of water oxidation are determined to be hydroxyl radicals and hydrogen peroxide. Moreover, BiVO₄-NS also shows obviously enhanced photoactivity than that of the commercially available BiVO₄ nanoparticles (BiVO₄-C). The improved photoactivity of BiVO₄-NS is attributed to the effective charge separation and low charge transfer resistance. The underlying mechanism of sonication-promoted water splitting is investigated by a variety of controlled experiments. The results show that ultrasonic waves can produce obvious strain inside the sample, which results in lattice distortion of BiVO₄. Therefore, the conduction band of BiVO₄ is obviously negative shifted, which is beneficial for H₂ production. In addition, the strain in BiVO₄ also produces local polarization of the sample, which effectively promotes the charge transfer and separation process. It is hoped that our study could provide a new strategy for achieving efficient photocatalytic water splitting.