Construction of Bi/Bi₂S₃/TiO₂ S-Scheme Heterojunction for Enhanced Photothermal Catalytic CO₂ Reduction

The ternary Bi/Bi₂S₃/TiO₂ (BST) heterojunction was successfully fabricated through integration of the hydrothermal method combined with thermal calcination. TiO₂ nanosheets serves as the host for the in situ deposition of Bi₂S₃ and Bi nanoparticles, and the tight interface with the heterojunction favors efficient charge transfer. Bi₂S₃ with a narrow band gap characteristic enables UV-visible-infrared full-spectrum absorption, and metallic Bi with a surface plasmon resonance (SPR) effect generating hot electron injection can effectively transfer and separate photogenerated charge carriers. The BST catalyst shows a broad-spectrum response and excellent photothermal effect, which could absorb near-infrared energy and improve the CO₂ reduction performance. Furthermore, the surface temperature of the BST composite reaches 109.0 °C within 10 min, exhibiting an excellent photothermal catalytic CO production rate of 175.94 μmol g^-1 h^-1 at 70 °C, which is ∼6.5 times higher than that of pristine TO₂. The excellent photocatalytic performance can be ascribed to the unique ternary heterojunction structure with suitable band gap structure. Localized heating not only accelerates carrier migration but also thermally activates CO₂ adsorption. This work advances the design of full-spectrum-driven photothermal catalytic systems for the efficient catalytic conversion of CO₂.