Basal Plane Activation of SnS 2 Thin‐Film by Fluorine Doping for Selective Solar‐Driven CO 2 Reduction With Enhanced Quantum Efficiency

ABSTRACT Photocatalytic conversion of CO 2 into value‐added fuels offers a viable approach to combat climate change and address global energy demands. Here, we present a fluorine‐doped SnS 2 thin film with sulfur vacancy (i.e., S V ‐SnS 2 :F), prepared via thermal evaporation, post‐sulfurization, and fluorine ion‐implantation. Substitution of sulfur with fluorine and sulfur vacancy formation changes the product selectivity from CH 4 to CO with about 40‐fold enhanced yield and boosted internal quantum efficiency ( IQE ) of 0.52%. Transient absorption, in situ near‐ambient pressure X‐ray photoelectron, and in situ Fourier transform infrared spectroscopies, along with first‐principles density functional theory calculations, suggest that nearest‐neighbor Sn to F serves as an active site and stabilizes the *COOH intermediate. Our findings shed light on how F doping activates the nearby elements and its crucial role in intermediate stabilization toward selectivity change in a heterogeneous photocatalysis process.