Modulation of NH₂‐UiO‐66 Based MOFs for Gas Phase CO₂ Photocatalytic Reduction

Abstract To solve both the greenhouse effect and energy crisis issues, direct capture and conversion of CO 2 appears as a promising contribution. Artificial photosynthesis is an encouraging and very attractive complementary way to convert CO 2 into high‐value‐added chemicals. Nevertheless, efficient CO 2 conversion remains challenging, mainly due to the poor CO 2 adsorption , the high activation energy required to break C═O bonds, and the slow dynamics of charge carriers in light‐harvesting materials. In recent years, some Metal‐organic frameworks (MOFs) have emerged in the photocatalysis field, especially due to their huge CO 2 adsorption capability and light‐harvesting properties behavior. In this study, a series of defective NH 2 ‐UiO‐66 MOF materials, using formic acid (FA) is synthesized as a modulating agent. Then, a series of binary (MOF/TiO 2 ) catalysts is obtained by varying the defective MOFs content, followed by further deposition of gold (Au) nanoparticles (NPs) to result in three‐component MOF/TiO 2 /Au composites. These composites are assessed for gas‐phase CO 2 photoreduction in the presence of water vapor as the only reducing agent. This hybrid ternary photocatalyst not only increases CO 2 adsorption but also promotes CH 4 formation. Among these resulting MOF/TiO 2 /Au samples, the optimized photocatalytic activity results in a mean production rate of 17.2 µmol.h −1 .g −1 catalyst of CH 4 , which is 6‐fold higher than the one observed for the reference TiO 2 /Au photocatalyst.