WO3 Nanosheet/ZnIn2S4 S-Scheme Heterojunctions for Enhanced CO2 Photoreduction

The nanostructure of the photocatalyst plays a crucial role in determining its catalytic ability. In this paper, a 2D/2D WO3/ZnIn2S4 S-scheme heterojunction was successfully prepared through a simple hydrogen reaction. Under UV–vis light irradiation, the yield of CO in the CO2 photoreduction process using WO3/ZnIn2S4 as the catalyst reached about 44.61 μmol·g–1, which was about 3.9 times higher than that obtained with ZnIn2S4 alone. Cycling experiments demonstrated that the binary composite exhibited excellent photocatalytic activity and material stability. Photoelectrochemical measurements revealed that the 2D/2D WO3/ZnIn2S4 S-scheme heterojunction significantly enhanced the separation efficiency of photogenerated carriers and effectively improved the redox ability of the photocatalyst. Density functional theory calculations were employed to analyze the electron transfer pathways and the formation of the built-in electric field at the 2D/2D WO3/ZnIn2S4 interface, confirming that the heterojunction structure accelerated the transfer of photogenerated electrons from WO3 to ZnIn2S4. The CO2 photoreduction process was further investigated by in situ FTIR. Finally, a possible S-scheme electron transfer mechanism at the 2D–2D WO3/ZnIn2S4 interface during the CO2 photoreduction reaction was proposed and discussed.