Organic amine surface modified one-dimensional CdSe0.8S0.2-diethylenetriamine/two-dimensional SnNb2O6 S-scheme heterojunction with promoted visible-light-driven photocatalytic CO2 reduction

Achieving a strong redox ability and high visible-light absorption ability in a single semiconductor material is difficult. Designing a heterojunction between two semiconductor materials is a feasible method. The new step (S-scheme) heterojunction can effectively promote the separation and transfer of photogenerated electron-hole pairs and retain strong redox ability. We designed and prepared a CdSe0.8S0.2-diethylenetriamine (DETA)/SnNb2O6 heterostructure material via the solvothermal method. When CdSe0.8S0.2-DETA and SnNb2O6 form an S-scheme heterojunction, 30%CdSe0.8S0.2-DETA/SnNb2O6 exhibits the highest CO production rate (17.31 μmol·g–1·h–1), which is factors of 2.8 and 4.8 higher than that of traditional solvothermal SnNb2O6 (6.2 μmol·g–1·h–1) and CdSe0.8S0.2-DETA (3.6 μmol·g–1·h–1), respectively. X-ray photoelectron spectroscopy characterization data provided evidence that the transfer pathway of space charge in the CO2 reduction process was in accordance with the S-scheme. This research provides a simple strategy through which one can optimize the band structure to promote the separation of photogenerated carriers and achieve a high efficiency of CO2 reduction.