Z-scheme heterojunction of SnS2-decorated 3DOM-SrTiO3 for selectively photocatalytic CO2 reduction into CH4

ABSTRACT The rapid recombination of photoinduced electron-hole pairs as well as the deficiency of high-energy carriers restricted the redox ability and products selectivity. Herein, the heterojunction of SnS2-decorated three-dimensional ordered macropores (3DOM)-SrTiO3 catalysts were in-situ constructed to provide transmit channel for high-energy electron transmission. The suitable band edges of SnS2 and SrTiO3 contribute to the Z-scheme transfer of photogenerated carrier. The 3DOM structure of SrTiO3-based catalyst possesses the slow light effect for enhancing light adsorption efficiency, and the surface alkalis strontium is benefit to the boosting adsorption for CO2. The in-situ introduced SnS2 decorated on the macroporous wall surface of 3DOM-SrTiO3 altered the primary product from CO to CH4. The Z-scheme electron transfer from SnS2 combining with the holes in SrTiO3 occurred under full spectrum photoexcitation, which improved the excitation and utilization of photogenerated electrons for CO2 multi-electrons reduction. As a result, (SnS2)3/3DOM-SrTiO3 catalyst exhibits higher activity for photocatalytic CO2 reduction to CH4 compared with single SnS2 or 3DOM-SrTiO3, i.e., its yield and selectivity of CH4 are 12.5 μmol g-1 h-1 and 74.9%, respectively. The present work proposed the theoretical foundation of Z-scheme heterojunction construction for enhancing photocatalytic activity and selectivity for CO2 conversion.