Enhanced photo-enzyme CO2 reduction using PEI-modified TPDE/SFN-FE photoenzyme composite catalysts

Abstract

In the pursuit of carbon neutrality, enzymatic CO₂ reduction offers high selectivity and efficiency under mild conditions. However, the poor stability and reusability of free enzymes limit practical applications. To address this issue, we developed a novel “two-in-one” photo-enzymatic system. Formate dehydrogenase (FDH) is immobilized on mesoporous silica nanoflowers (SF_N) via electrostatic adsorption, improving enzyme stability and recyclability. Integrated with a PEI-modified diaminoanthraquinone covalent organic framework (TPDE), this system achieves efficient CO₂ reduction under light, yielding formic acid at 5580 μmol g⁻¹ h⁻¹, outperforming most reported values. The electron transfer pathway was elucidated through rotating disk electrode analysis, demonstrating the preferential role of enzyme-mediated CO₂ reduction over direct photoreduction. This study provides new insights into the dynamics of photo-enzymatic cascade systems and presents a promising strategy for sustainable CO₂ conversion toward carbon neutrality.