Engineered nickel-based metal − organic framework nanofiber membrane with fish-scale microstructure for enhanced photocatalytic CO₂ conversion

Metal-organic frameworks (MOFs) have attracted considerable interest due to their wide-ranging applications in heterogeneous catalysis. However, their limited separation efficiency and challenging recovery from reaction mixtures pose practical challenges. Membrane-based catalysts offer a solution by preventing light scattering and aggregation while enabling easier recovery compared to powdered catalysts. While MOF membranes have been extensively studied for photocatalytic pollutant decomposition, their application in photocatalytic CO₂ reduction remains underexplored. Hence, in this study, we present the successful immobilization of defective Ni-MOF-74 (NMD) nanofragments containing more unsaturated Ni active sites onto electrospun polyacrylonitrile (PAN) nanofiber membranes (NFMs). The resulting composite catalyst, referred to as NMD/PAN NFMs (NPNs) with a uniform fish-scale microstructure, was evaluated for photocatalytic CO₂ reduction under mild conditions. The results demonstrate exceptional photocatalytic performance and stability of NPNs. The membranes exhibited a CO production rate of 1,641 μmol g^-1h⁻¹ with a selectivity of 91 %, surpassing even that of powdered NMD. Moreover, the NPNs demonstrated advantages such as ease of recycling and reusability, further enhancing their practical applicability. This innovative approach to constructing high-performance MOF nanofiber membranes opens up new possibilities for a broader range of applications in CO₂ photocatalytic conversion. © 2025