NH2-UIO-66 Based Hydrophobic Porous Liquid with High Mass Transfer and Affinity Surface for Enhancing CO2 Photoreduction

Increasing the CO 2 concentration on the surface of the photocatalysts helps to increase the reaction dynamic rate of the photocatalytic CO 2 reduction. However, the low solubility and poor mass transfer of CO 2 in aqueous phase seriously hinder the adsorption and conversion of CO 2 at the active site. In this work, the porous liquid photocatalyst (NH 2 -UIO-66 PL) with strong hydrophobicity has been synthesized by grafting the hydrophobic liquid end long-chain (PDMS) onto the amino site of metal-organic framework (NH 2 -UIO-66). It is found that the NH 2 -UIO-66 PL with permanent porosity causes a large amount of CO 2 to be concentrated in the porous liquid cavity for transporting and diffusing CO 2 onto the photocatalyst surface rapidly, and then the CO 2 affinity surface with high positive potential and key intermediates for activation reduction reactions are formed with the grafting of hydrophobic PDMS, leading to stronger electron enrichment Zr active sites for enhancement of the overall CO 2 reduction ability. As a result, NH 2 -UIO-66 PL achieved CO 2 photoreduction with a CO yield of 24.70 μmol∙g −1 ∙h −1 and CH 4 yield of 7.93 μmol∙g −1 ∙h −1 , which is 2.3-fold and 2.7-fold compared to hydrophilic NH 2 -UIO-66, respectively. This research provides a novel design of hydrophobic porous liquids to provide industrial possibilities for high CO 2 adsorption and reduction. The NH 2 -UIO-66 PL with permanent porosity promotes the enrichment of CO 2 in the porous liquid, which facilitates the rapid transport and diffusion of CO 2 to the surface of the photocatalyst.