Multifunctional Nano-COF-Embedded Silica Composite for Efficient Photocatalytic NADH Regeneration

The photocatalytic regeneration of NADH represents an effective means of mimicking photosynthesis, but confronts the challenges of the charge separation, electron transfer, and the selectivity control in the surface reduction stage. Herein, we report a multifunctional composite material that embeds β-ketoenamine-linked nano TPTTA covalent organic frameworks (COFs) and electron mediator (rhodium complex, [Cp*Rh(bpy) (H₂O)Cl₂] into a functional mesoporous silica matrix for photocatalytic NADH regeneration. This strategy enables the facilitation of the electron transfer process while maintaining the intrinsic properties of the COFs, providing flexibility in COFs design. The strategic integration of electron mediator and the shortened charge migration path due to the nanosized COFs results in an NADH regeneration yield of 75.7% and a selectivity of 89.8% for 1,4-NADH. The initial reaction rate for NADH regeneration attained 8.7 g_NADH•g_Cat ^-1•h^-1, and the system showed no decrease in activity after four reaction cycles.