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

Abstract

Solar-driven photothermal CO₂ reduction into multicarbon (C₂⁺) products represents a promising yet challenging route for sustainable fuel production. A key obstacle remains the inefficient C–C coupling due to poor CO₂ activation and limited charge utilization, especially under full-spectrum light. Herein, we propose a heterojunction photocatalyst that synergistically integrates the topological insulator Bi₂Te₃ with oxygen-doped TiO_2-X to address these challenges. The metallic nature of Bi₂Te₃ 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 CO₂ adsorption, bending, and activation. The built-in electric field formed at the heterointerface drives efficient electron transfer from Bi₂Te₃ 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 Bi₂Te₃/TiO_2-X catalyst achieves a remarkable C₂⁺ production rate of 15.08 μmol g⁻¹ h⁻¹ with selectivity toward C₂H₄ and C₂H₆. 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 CO₂-to-C₂⁺ conversion.