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

Abstract Solar‐driven selective reduction of CO 2 to C 2 H 4 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 CO 2 activation and C–C coupling, thereby increasing the *CO intermediate concentration and lowering the C–C coupling energy barrier. Concurrently, Ag sites preferentially catalyze H 2 O dissociation, providing active hydrogen for the subsequent protonation of *OCCO intermediates, thus increasing the overall C 2 H 4 formation rate. The optimized Ti─Cl─Ag catalysts achieve high C 2 H 4 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 CO 2 to C 2 H 4 .