Enzyme-Inspired Design of Well-Defined Dual-Metal-Site Pairs Confined within Metal–Organic Frameworks for Tailoring Photocatalytic Microenvironments

Activity–selectivity trade-off remains a grand challenge and crucial issue in artificial photosynthesis. As for the natural enzyme system, bimetallic clusters confined in protein-folding chains enable regulating the activity–selectivity equilibrium for photosynthesis. However, current artificial photocatalysts lack the precisely synergistic control over active site configuration and catalytic microenvironments, causing the compromised trade-off between activity and specificity. Herein, we developed a “ship-in-bottle” strategy to confine well-defined dual-metal-site pairs (DMSPs) Co 2 L 2 in the cage of amino-functionalized metal–organic framework UiO-67-(NH 2 ) 2, aiming at synergistic regulation of selectivity and activity for photocatalytic CO 2 reduction. The as-synthesized Co 2 L 2 @UiO-67-(NH 2 ) 2 realized the highest syngas yield with CO/H 2 ≈ 1/1, whereas only H 2 but no CO was detected for original Co 2 L 2 . It was demonstrated that the tailored microenvironment around DMSPs enhanced the specific adsorption of CO 2 like that in enzymes. Furthermore, the electron consumption rate of Co 2 L 2 @UiO-67-(NH 2 ) 2 (11078.00 μmol·g DMSP –1 ·h –1 ) was 63-fold higher than that of the Co 2 L 2 +UiO-67-(NH 2 ) 2 physical mixture counterpart (174.30 μmol·g DMSP –1 ·h –1 ), ascribing to the synergistic catalytic effect of DMSPs and improved charge transfer. As a proof of concept, this work integrates dual-metal-site catalysts with local microenvironment engineering to suppress the kinetically favored hydrogen evolution pathway and accelerate the CO 2 reduction reaction process, providing a novel and feasible approach for optimizing artificial photosynthesis.