Dynamic Dual-Site Relay Catalysis Enables Selective Solar-Driven CO2 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. Graphical Single-atom In-decorated defective WO 3-x establishes a dynamic dual-site relay for selective CO 2 photoreduction. Oxyphilic In traps electrons to anchor *CO via O-donation, while adjacent W sites facilitate *OCCO formation through d-orbital hybridization. This synergy directs C−C coupling and selective hydrogenation, achieving 86.35% ethanol selectivity without sacrificial agents.