Confined Polyhydroxylated C60 in Porphyrin COF Nanopore as Nanoreactor for CO2 Photoreduction

The topological nanopores of covalent organic frameworks (COFs) are promising platforms for constructing photocatalytic nanoreactors for CO 2 conversion. However, simultaneously increasing electron density, promoting electron transfer, and enhancing CO 2 adsorption and activation within confined nanopore spaces remain critical challenges for boosting photocatalytic performance. Herein, polyhydroxylated fullerene (C 60 OH) molecules were assembled within the nanopores of a two-dimensional porphyrin-based COF (pCOF) through hydrogen-bonding interactions with the hydroxyl-functionalized 2,5-dihydroxyterephthalaldehyde (DHTA) acceptor units in the pCOF, thereby constructing a C 60 OH@pCOF photocatalytic nanoreactor featuring DHTA–C 60 OH molecular heterojunctions. Under full-light irradiation, the optimized C 60 OH@pCOF achieves a CO production rate of 40.47 μmol/(g·h) in pure water, approximately four times higher than that of pristine pCOF, along with a CO selectivity of 99%. This remarkable enhancement is mainly attributable to the introduction of C 60 OH molecules into the pCOF, which facilitates the directional transfer of photogenerated electrons from the porphyrin donor to the DHTA moieties and then to the C 60 OH acceptor. Moreover, the abundant surface hydroxyl groups on C 60 OH serve as metal-free catalytic sites that effectively activate pre-accumulated CO 2 within the nanopore-based reactor and promote the formation and conversion of key intermediates. This study provides new insights into the design and construction of porous crystalline framework-based photocatalytic nanoreactors.