Spatially Separated C–C Coupling and Protonation on Cl‐Bridged Ti–Ag Dual‐Site Catalysts for Efficient Photocatalytic CO ₂ Reduction to C ₂ H ₄

Solar-driven selective reduction of CO₂ to C₂H₄ conversion is bottlenecked by the concurrent demands for intermediate protonation and C-C coupling. Herein, we constructed a chlorine (Cl)-bridged Ti-Ag dual-site catalysts to overcome above issues. The introduction of Cl on Ti-Ag dual sites spatially separates C-C coupling and intermediate protonation, making *CO dimerization thermodynamically more favorable than *CO hydrogenation. In situ characterization and DFT calculations reveal that the Cl enables the Ti sites within the Ti─Cl─Ag configuration act as active center for CO₂ activation and C-C coupling, thereby increasing the *CO intermediate concentration and lowering the C-C coupling energy barrier. Concurrently, Ag sites preferentially catalyze H₂O dissociation, providing active hydrogen for the subsequent protonation of *OCCO intermediates, thus increasing the overall C₂H₄ formation rate. The optimized Ti─Cl─Ag catalysts achieve high C₂H₄ production rate of 244 µmol·g^-1·h^-1 with 64.3% selectivity, outperforming O-bridged Ti-Ag catalysts which mainly favor *CO deep hydrogenation. This work establishes spatially separated Ti-Ag dual sites that orchestrates site-specific C-C coupling and active hydrogen feeding, providing a rational design concept of photocatalysts for selective reduction of CO₂ to C₂H₄.