Single‐Atom‐Layer Metallization of Plasmonic Semiconductor Surface for Selectively Enhancing IR‐Driven Photocatalytic Reduction of CO2 into CH4

Abstract Efficient harvesting and utilization of abundant infrared (IR) photons from sunlight is crucial for the industrial application of photocatalytic CO 2 reduction. Plasmonic semiconductors have significant potential in absorbing low‐energy IR photons to generate energetic hot electrons. However, modulating these hot electrons to selectively enhance the activity of CO 2 reduction into CH 4 remains a challenge. Herein, the study proposes a single‐atom‐layer (SAL) metallization strategy to enhance the generation of IR‐driven hot electrons and facilitate their transfer from plasmonic semiconductors to CO 2 for producing CH 4 . This strategy is demonstrated using a paradigmatic W 18 O 49 @W‐Sn nanowire array (NWA), where Sn 2+ ions are grafted onto exposed O atoms on the surface of plasmonic W 18 O 49 to form a surface W‐Sn SAL. The incorporation of Sn single atoms enhances plasmonic absorption in IR light for W 18 O 49 NWA. The W‐Sn SAL not only promotes CO 2 adsorption and reduces its reaction activation energy barrier but also shifts the endoergic CO‐protonation process toward an exoergic reaction pathway. Thus, the W 18 O 49 @W‐Sn NWA exhibits >98% selectivity for IR‐driven CO 2 reduction to CH 4 with an activity over 9.0 times higher than that of bare W 18 O 49 NWA. This SAL metallization strategy can also be applied to other plasmonic semiconductors for selectively enhancing CO 2 ‐to‐CH 4 reduction reactions.