Ultrathin 2D/2D ZnIn2S4/La2Ti2O7 nanosheets with a Z-scheme heterojunction for enhanced photocatalytic hydrogen evolution

Abstract

Layered lanthanum titanate (La₂Ti₂O₇) perovskite is a good photocatalytic material owing to its high stability, strong redox ability, and non-toxicity. However, its inherent wide bandgap limits its application in photocatalytic hydrogen evolution. Therefore, combining La₂Ti₂O₇ with two-dimensional (2D) narrow-bandgap semiconductors to form 2D/2D layered structures is the preferred strategy to improve its photocatalytic performance. In this study, a novel 2D/2D ZnIn₂S₄/La₂Ti₂O₇ Z-scheme heterojunction was prepared through a solvothermal method. The experimental results show that when the molar ratio of La₂Ti₂O₇ to ZnIn₂S₄ is 1 : 4, the hydrogen evolution rate of the composite under ultraviolet-visible light reaches 6.97 mmol g⁻¹ h⁻¹, which is 3.5 times higher than that of the pure ZnIn₂S₄. The results of the morphological characterization studies of the samples and the photoelectrochemical measurements show that channels for the rapid transfer of carriers are generated by the unique 2D/2D structure of these samples, and the separation and migration efficiency of the photogenerated carriers significantly improved due to the formation of the Z-scheme heterojunction. This study provides useful insights into the modulation of wide-bandgap semiconductors and research into solar energy conversion.