3D/0D Cu3SnS4/CeO2 Heterojunction Photocatalyst with Dual Redox Pairs Synergistically Promotes the Photocatalytic Reduction of CO2

As an inexpensive bimetallic sulfide with a narrow band gap, Cu3SnS4 has been widely used in solar-energy-driven catalytic reactions. However, the traditional tetragonal Cu3SnS4 has the inherent defect of fewer surface active sites and poor photogenerated carrier transport performance, which requires further modification to improve the CO2 photocatalytic reduction performance of tetragonal Cu3SnS4. In this work, the Cu3SnS4/CeO2 binary composites with dual redox pairs of Ce4+/Ce3+ and Cu2+/Cu+ were successfully designed and prepared via a simple solvothermal method as a bridge for the synthesis of composite materials. A series of characterizations, such as X-ray diffraction (XRD), energydispersive spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), electron paramagnetic resonance (EPR), photocurrent (PC), electrochemical impedance spectroscopy (EIS), etc., have confirmed that dual redox pairs and heterojunction synergistically improve the photochemical properties of hybrid Cu3SnS4/CeO2. Because of the unique three-dimensional/zero-dimensional (3D/0D) hierarchical structure of Cu3SnS4/CeO2, the splendid light absorption characteristic of Cu3SnS4 was retained, and the specific surface area of CC1 composite was improved. In addition, the water static contact angle experiments showed that the hydrophilicity of composites is inhibited. As a consequence, the fabricated CC1 composite with dual redox pairs acquires CO evolution that is 2.63 times greater than that observed for pristine Cu3SnS4. The innovative study will provide a feasible orientation for the field of solar energy-driven CO2 reduction reaction.