Low molecular state porous liquids with exposed active sites and faster electron transfer heterointerfaces for photocatalytic CO2 reduction

Abstract

Converting excess emitted CO2 into high-value-added chemicals via photocatalysis is a promising and sustainable strategy. The integration of powder photocatalysts and liquid matrices in porous liquids can mitigate the bottleneck of slow CO2 mass transfer in conventional gas-solid-liquid threephase systems. However, powder photocatalysts serving as catalytic hosts in porous liquids are tightly encapsulated by liquid matrices that act as largesized sterically hindered solvents, leading to the coverage of active sites on the catalyst surface as well as reduced photo-response efficiency. Herein, UIO-66-LV porous liquid (PL) was successfully synthesized using the smallmolecule compound state [M2070][PSS] ionic liquid (PIL) as the liquid phase and NH2-UIO-66 as the solid phase. The liquid matrices of the PL, in a smallmolecule state, forms a loose solid-liquid heterojunction interface, which fully exposes the active sites on the solid phase and expands the reaction contact area between the catalyst and CO2 molecules, thereby significantly enhancing the photo-response efficiency and electron transfer capability. Ultimately, the photocatalytic activity of the PL reached 5 times that of the powder photocatalyst NH2-UIO-66. This work provides a novel strategy for constructing efficient CO2 reduction photocatalytic systems.