Reverse Electron Transfer-Induced SnS₂ Phase Transition for Efficient Photocatalytic CO₂–C₂H₆ Conversion

Two-dimensional metal sulfides such as SnS2 play a pivotal role in the field of environmental energy due to their suitable optical bandgap and high specific surface area. However, the steady-state 2H-phase SnS2 suffers from rapid charge recombination and low CO2 catalytic activity, limiting its practical application in photocatalytic CO2 reduction. In this work, we designed a CuPd/SnS2 heterojunction system by loading CuPd nanoparticles onto SnS2 nanosheets (NSs). Under illumination, the hot electrons excited in CuPd nanoparticles induce a 2H-1T-phase transition of SnS2, effectively improving the photogenerated carrier dynamics of the material. Additionally, the post-transition energy level structure facilitates more efficient injection of photogenerated electrons into highly catalytic CuPd particles, achieving the goal of photocatalytic reduction of CO2 to C2H6. Resultingly, the CuPd/SnS2 photocatalytic system achieves a C2H6 production rate of 255.6 μmol g–1 h–1, which is approximately 24.4 times and 3.9 times higher than that of Cu/SnS2 and Pd/SnS2, respectively. Moreover, it boasts a remarkable product selectivity of up to 90.4% for C2H6. This study provides a valuable approach for modulating photogenerated carrier dynamics and enhancing catalytic activity in two-dimensional metal sulfides.