Highly Selective Ethylene Production from Solar-Driven CO₂ Reduction on the Bi₂S₃@In₂S₃ Catalyst with In–S_V–Bi Active Sites

Photothermal catalysis that utilizes solar energy to not only generate charge carriers but also supply heat input represents a potentially sustainable strategy for the efficient conversion of CO2 to valuable chemicals. It is highly desirable to develop photothermal catalysts with broadband light absorption across the whole solar spectrum, efficient photothermal conversion, and appropriate active sites. In this work, the Bi2S3@In2S3 heterostructure catalyst is fabricated via one-step solvothermal synthesis, where Bi2S3 serves as a photothermal material and synchronously affords photoexcited charge carriers. Experimental results indicate that the photoinduced charge carriers trigger H2O-assisted CO2 reduction and the elevated temperature kinetically accelerates the reaction. Furthermore, the tightly bonded heterointerfaces provide unique In–SV–Bi active centers consisting of adjacent Bi and In atoms coupled with sulfur vacancies, which reduces the energy barriers of CO2 activation and C–C coupling, facilitating the generation and dimerization of CO intermediates for highly selective C2H4 production. The integration of In–SV–Bi active sites and the photothermal effect into the Bi2S3@In2S3 catalyst induces a high rate of 11.81 μmol gcat–1 h–1 and near 90% selectivity for CO2 conversion to C2H4 under simulated sunlight without extra heat input. The catalytic mechanism is expounded by in situ characterizations and theoretical calculations. This work would provide some enlightening guidance to construct efficient photothermal catalysts for the direct transformation of CO2 to multicarbon (C2+) products with solar energy.