S-scheme CoTiO3/Cd9.51Zn0.49S10 heterostructures for visible-light driven photocatalytic CO2 reduction

Abstract

• Hierarchial CoTiO 3 /Cd 9.51 Zn 0.49 S 10 heterostructures were fabricated by growing Cd 9.51 Zn 0.49 S 10 nanowires on CoTiO 3 microprism in situ via a hydrothermal method. • The transfer path of photogenerated charge carriers in CoTiO 3 /Cd 9.51 Zn 0.49 S 10 heterostructure follows a S-scheme mechanism. • The CoTiO 3 /Cd 9.51 Zn 0.49 S 10 hybrids manifest high activity and good stability for photocatalytic CO 2 reduction, achieving an AQE of 7.27% at 420 nm. Cd 1− x Zn x S solid solutions with strong light absorption are promising materials for solar-driven CO 2 reduction; however, their relatively weak redox ability and intrinsic photo-corrosion limit their further development as a photocatalyst. The addition of a second photocatalyst with a suitable band structure to construct a S-scheme photocatalytic system can solve both problems simultaneously. Here, we report a S-scheme photocatalyst based on the heterostructure of CoTiO 3 /Cd 9.51 Zn 0.49 S 10 (abbreviated as CoTiO 3 /CdZnS) that enables the efficient photocatalytic reduction of CO 2 . Detailed physicochemical characterization resolves the S-scheme charge transfer mechanism in this composite photocatalyst. With the well-designed structure of particles and desirable band offsets, this hybrid system offers visible light absorption in a broad spectral region, large surface area, strong redox ability, and fast carrier separation and transportation. Under visible-light illumination, the CoTiO 3 /CdZnS hybrid system displays a CO formation rate of about 11 mmol h −1 g −1 combined with a long-term operational stability. Besides, a high apparent quantum efficiency (AQE) of 7.27% is realized for the CO 2 -to-CO reduction reaction by the optimized CoTiO 3 /CdZnS hybrid under 420 nm monochromatic light irradiation.