MIL-68 (In)-derived In2O3@TiO2 S-scheme heterojunction with hierarchical hollow structure for selective photoconversion of CO2 to hydrocarbon fuels

The hierarchical hollow structured photocatalysts of TiO2 nanosheet arrays-decorated In2O3 hexagonal nanotubes (core–shell structural In2O3@TiO2) were successfully fabricated by the in-situ hydrothermal method. Hierarchical hollow structure of In2O3@TiO2 photocatalysts with large specific surface area can improve the light harvesting efficiency and the adsorption capability for CO2 and H2O reactants. The internal electric field in In2O3@TiO2 photocatalysts provides the strong driving force for S-scheme electron transfer from conduction band of TiO2 to valence band of In2O3. The In2O3@TiO2 catalysts exhibited super performance for selectively photocatalytic CO2 conversion with H2O into hydrocarbon fuel (CH4) without sacrificial agent. Among the catalysts, In2O3@TiO2-10 catalyst has the largest yield (11.1 μmol g−1h−1) and selectivity (88.1 %) of CH4 product. Based on results of the characterizations, the mechanism of selective CO2 photoreduction is proposed: the surface enrichment of photogenerated electron induced by the S-scheme In2O3-TiO2 heterojunction is key-step for selective CO2 photoreduction into CH4. This work provides new ideas for the design and construction of high-efficient S-scheme photocatalysts.