Abstract: The combination of S-scheme heterojunction and photothermal effect is a promising strategy to achieve efficient CO₂ photoreduction into solar fuel due to the boosted charge carrier separation efficiency and faster surface reaction rate. Herein, unique photothermal-coupled TiO₂/Bi₂S₃ S-scheme heterojunction nanofibers were fabricated and applied to a full-spectrum CO₂ photoreduction system. Density functional theory calculation and experimental analyses have confirmed the generation of the internal electric field and the S-scheme electron transfer pathway, leading to a highly efficient charge carrier separation. Thanks to the excellent photothermal conversion capacity of Bi₂S₃, the photogenerated electron transfer rate, and surface reaction rate were further accelerated in hybrid photocatalysts. Under the synergistic effect of S-scheme heterojunction and photothermal effects, the optimal TiO₂/Bi₂S₃ nanofibers achieved 7.65 μmol h^-1 of CH₄ production rate, which is 5.24 times higher than that of pristine TiO₂. Moreover, the morphology reconstruction of Bi₂S₃ in hybrids facilitates the CH₄ selectivity was significantly improved from 64.2% to 88.7%. Meanwhile, the CO₂ photoreduction reaction route over TiO₂/Bi₂S₃ nanofibers was investigated based on in-situ Fourier transform infrared spectra. This work provides some useful hints for designing highly efficient photothermal-coupled photocatalysts for CO₂ photoreduction.

Key words: TiO₂/Bi₂S₃, S-scheme heterojunction, Photocatalytic CO₂ reduction, Photothermal effect