Two birds with one stone: S-scheme charge transfer enables simultaneous efficient photocatalytic complete methanation of CO2 and benzimidazole synthesis

Solar-driven photocatalytic CO 2 -to-CH 4 conversion represents a promising strategy to mitigate the energy and climate crisis. However, it is still challenging to achieve efficient CO 2 conversion due to the difficulties of CO 2 activation, sluggish kinetics of water oxidation half-reaction and high cost of sacrificial agents in conventional reaction systems. Herein, by precisely integrating bimetallic sulfide with functionalized UiO-66 to construct a Cu 0.1 Zn 0.9 S/Bim-UiO-66 S-scheme heterojunction photocatalyst, which innovatively accomplished complete CO 2 methanation and benzimidazole synthesis in one redox cycle. Experimental results reveal that the optimized photocatalyst exhibited an exceptional CH 4 production rate of 35.2 μmol h −1  g −1 (selectivity of 100 %) and 92 % benzimidazole conversion under simulated solar irradiation. Mechanistic studies demonstrate that the S-scheme heterojunction significantly enhances photogenerated charge carrier separation efficiency through the establishment of a built-in electric field, while preserving the strongest redox potentials of the two semiconductors. Remarkably, the benzimidazole synthesis process replaced conventional H 2 O oxidation, proving beneficial for CO 2 -to-CH 4 conversion. This work provides new insights into designing high-performance photocatalysts for CO 2 conversion and the synthesis of fine chemicals.