Promoting photothermal catalytic CO2 reduction of Cd2In2S5/Cd0.3Zn0.7S heterojunction with encapsulated hydrogen evolution active site by accelerating charge transfer kinetics

The photothermal catalysis CO2 reduction is considered as an attractive means to solve the greenhouse effect and energy crisis. However, due to the slow charge transfer kinetics on the surface of the catalyst and sparse adsorption active site, the CO2 adsorption rate is low and the carrier life is short. So, the catalytic performance is limited. Here, a core–shell similar structure catalyst for photothermal CO2 reduction was constructed by growing of Cd0.3Zn0.7S (CZS) nanospheres on the surface of sulfur defect rich Cd2In2S5 (CIS) ultra-thin nanosheets, and which was coordinated by the interfacial chemical bond and the interfacial internal electric field. The Cd-S chemical bond became a direct channel to accelerate the transfer of electrons from the conduction band of CZS to the conduction band of CIS, leading to higher surface charge localization of CIS/CZS, and encapsulating the active site of hydrogen evolution of CZS. The core–shell similar structure was favorable for the spatial separation of photogenerated charges. The production of *HCO3– and *COOH intermediates on the CIS/CZS surface has been proved to be crucial for CO2 adsorption and CO generation by in situ Fourier transform infrared spectroscopy. The charge transfer mechanism of Type Ⅱ between CIS and CZS was proved by density functional theory calculation and in situ X-ray photoelectron spectroscopy. The CO yield of the optimized CIS/CZS heterojunction was 64.3 μmol·h−1·g−1, which was about 31.3 times that of pure CZS. This study provided a new idea for accelerating charge transfer dynamics and inhibiting competition reaction to promote the conversion of solar energy to fuel.