Dynamic Dual‐Site Relay Catalysis Enables Selective Solar‐Driven CO 2 Reduction Toward Ethanol

Photocatalytic CO 2 reduction to ethanol (C 2 H 5 OH) offers a sustainable carbon recycling route but is limited by inefficient C−C coupling under visible light irradiation. Here, we report a defect‐engineered WO 3‐x /In SAs (SAs, single atoms) photocatalyst with a dynamic dual‐site relay mechanism, where electron‐rich W−V O (V O , oxygen‐vacancy) and electron‐deficient In single atom sites cooperatively drive selective ethanol synthesis. The W−V O site acts as a persistent *CO supply hub for CO 2 ‐to‐*CO conversion, while In site functions as an ethanol‐selective coupling center for targeted *CO−*CO coupling. This relay enables exceptional ethanol production and high selectivity (97.43% electrons selectivity and 86.35% yield‐based selectivity). Notably, the photocatalyst maintains efficient CO 2 ‐to‐ethanol conversion efficiency under natural sunlight illumination in scaled‐up experiments using a reactor equipped with a 20 × 20 cm 2 plate coated with WO 3‐x /In SAs . Combined in situ spectroscopy and DFT calculations reveal that W−V O orchestrates CO 2 ‐to‐*CO feeding and relays electrons to In SAs , reducing the C−C coupling barrier via asymmetric electron distribution. Electron‐trapping at oxyphilic In stabilizes *CO via O‐lone‐pair donation; subsequent W d‐orbital hybridization anchors *OCCO, dictating ethanol selectivity. Our work provides a design strategy for efficient photogenerated carrier utilization in CO 2 ‐to‐ethanol conversion, with implications for scalable solar fuel synthesis.