Molten salt construction of core-shell structured S-scheme CuInS2@CoS2 heterojunction to boost charge transfer for efficient photocatalytic CO2 reduction

Weak redox ability and severe charge recombination pose significant obstacles to the advancement of CO2 2 photoreduction. To tackle this challenge and enhance the CO2 2 photoconversion efficiency, fabricating well-matched S-scheme heterostructure and establishing a robust built-in electric field emerge as pivotal strategies. In pursuit of this goal, a core-shell structured CuInS2@CoS2 2 @CoS 2 S-scheme heterojunction was meticulously engineered through a two-step molten salt method. This approach over the CuInS2-based 2-based composites produced an internal electric field owing to the disparity between the Fermi levels of CoS2 2 and CuInS2 2 at their interface. Consequently, the electric field facilitated the directed migration of charges and the proficient separation of photoinduced carriers. The resulting CuInS2@CoS2 2 @CoS 2 heterostructure exhibited remarkable CO2 2 photoreduction performance, which was 21.7 and 26.5 times that of pure CuInS2 2 and CoS2, 2 , respectively. The S-scheme heterojunction photogenerated charge transfer mechanism was validated through a series of rigorous analyses, including in situ irradiation X-ray photoelectron spectroscopy, work function calculations, and differential charge density examinations. Furthermore, in situ infrared spectroscopy and density functional theory calculations corroborated the fact that the CuInS2@CoS2 2 @CoS 2 heterojunction substantially lowered the formation energy of *COOH and *CO. This study demonstrates the application potential of S-scheme heterojunctions fabricated via the molten salt method in the realm of addressing carbon-related environmental issues. (c) 2024, Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.