In situ irradiated XPS investigation on S-scheme TiO2/Bi2S3 photocatalyst with high interfacial charge separation for highly efficient photothermal catalytic CO2 reduction

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.