Atomic Interlayer Mo-N₄ Sites Enable Rapid Charge Transfer and Efficient CO₂ Photoreduction

Photocatalytic CO₂ reduction is a promising route for sustainable carbon conversion, but its efficiency is often limited by poor charge separation and a lack of functional active sites. Here, we address these challenges by constructing an atomic Mo-N₄ interlayer electron bridge (IEB) within a bipyridine-based covalent organic framework (COF) via a photoreduction method. Guided by DFT screening, Mo was identified as the optimal metal center, enabling simultaneous CO₂ activation and ultrafast vertical electron transfer. The resulting Mo@Tp-Bpy catalyst achieves co-production rates of 948.0 µmol g^-1 h^-1 for CO and 3741.7 µmol g^-1 h^-1 for anisaldehyde via coupled CO₂ reduction and 4-methoxybenzyl alcohol oxidation, corresponding to 6.2-fold and 5.0-fold enhancements over the pristine Tp-Bpy COF, respectively. Mechanistic studies reveal that the Mo-N₄ sites facilitate interlayer charge kinetics and lower thermodynamic barriers for both half-reactions. This work presents a rational atomic-level strategy for integrating charge management and catalytic function in layered materials toward efficient photoredox catalysis.