Photocatalytic reduction of CO2 in cyclohexanol on CdS–TiO2 heterostructured photocatalyst

• CdS–TiO2 photocatalysts with different molar ratios were synthesized by two-step hydrothermal synthesis.
• CdS–TiO2 photocatalysts performed good activity under UV–vis light illuminated.
• Photocatalytic reduction of CO2 was investigated by using cyclohexanol as reductant.
• Cyclohexyl formate and cyclohexanone were producted by photocatalytic reduction of CO2 in cyclohexanol.

A nanosheet of CdS–TiO2 with heterojunction was prepared by a two-step hydrothermal synthesis method and used as a photocatalyst for reducing CO2 in cyclohexanol. This heterostructured composite has been characterized by X-ray diffractometer (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and ultraviolet-visible (UV–vis) diffuse reflectance spectroscopy (DRS). The activity of the CdS–TiO2 composite was tested in a batch slurry bed reactor. The results showed that CO2 absorbed in cyclohexanol was reduced to cyclohexyl formate (CF) on conduction band and the absorbent cyclohexanol was oxidized to cyclohexanone (CH) on valance band of the photocatalyst. It was revealed that the highest formation rates of 20.2 μmol/(gcat h) and 20.0 μmol/(gcat h) for CF and CH could be obtained when TiO2/CdS with the molar ratio of 8 was used. Overall, this work provides a novel pathway for photocatalytically reducing CO2 and preventing the catalyst from photocorrosion.

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