Mimicking natural photosynthesis: converting sunlight into solar fuel via a sustained photo-enzymatic catalytic system based on BT-NCOF architecture

Abstract

The photocatalytic reduction of carbon dioxide into energy-rich compounds has attracted much attention. However, it is still a challenge to convert CO₂ into value-added chemicals by utilizing solar energy. This work reports benzene-1,3,5-tricarbaldehyde (B) coupled with multi-amine linkers (4,4′,4′′-(benzene-1,3,5-triyltris(ethyne-2,1-diyl))trianiline (T)) as a nitrogen-rich covalent organic framework (BT-NCOF). BT-NCOF is afforded as a photocatalyst with highly ordered channels and abundant coordination active sites for small molecule activation. Under solar light irradiation, BT-NCOF acts as an efficient heterogeneous photosystem, utilizing its extended conjugation to use solar photons and drive the selective reduction of CO₂ to formic acid while simultaneously promoting NADH regeneration. The optimized BT-NCOF delivers remarkable solar to chemical conversion, achieving NADH regeneration with a yield of 60.34% and a formic acid yield of 157.56 µM. This study demonstrates that nitrogen-rich BT-NCOF can blend light-harvesting, charge-separation, and catalytic functions within a single modular scaffold, offering a robust platform for artificial photosynthesis and sustainable CO₂ conversion into solar fuels.