Synergistic Engineering of Oxygen Vacancies and Topological Surface States in Bi2Te3/TiO2-X Heterostructures for Highly Efficient Photothermal-Driven CO2 Photoreduction

Solar-driven photothermal CO 2 reduction into multicarbon (C 2 + ) products represents a promising yet challenging route for sustainable fuel production. A key obstacle remains the inefficient C–C coupling due to poor CO 2 activation and limited charge utilization, especially under full-spectrum light. Herein, we propose a heterojunction photocatalyst that synergistically integrates the topological insulator Bi 2 Te 3 with oxygen-doped TiO 2-X to address these challenges. The metallic nature of Bi 2 Te 3 enables broad-spectrum photon harvesting from UV to near-infrared and generates substantial photothermal heat, while the oxygen vacancies in TiO 2-X create an asymmetric electronic environment that promotes CO 2 adsorption, bending, and activation. The built-in electric field formed at the heterointerface drives efficient electron transfer from Bi 2 Te 3 to TiO 2-X , which suppresses charge recombination and ensures a prolonged electron supply for multistep reduction reactions. Under full-spectrum irradiation without external heating, the optimized Bi 2 Te 3 /TiO 2-X catalyst achieves a remarkable C 2 + production rate of 15.08 μmol g −1 h −1 with selectivity toward C 2 H 4 and C 2 H 6 . Combined photoelectronic measurements and theoretical analyses confirm that the synergistic photothermal–photocatalytic effect and tailored charge dynamics collectively lower the energy barrier for C–C coupling. This work offers a strategic material design leveraging topological insulators and defect engineering for efficient CO 2 -to-C 2 + conversion.