Cu-Metalated Porphyrin-Based MOFs Coupled with Anatase as Photocatalysts for CO 2 Reduction: The Effect of Metalation Proportion

Converting carbon dioxide (CO 2 ) into valuable chemicals such as fossil resources via photocatalysis requires the development of advanced materials. Herein, we coupled zirconium-based metal–organic frameworks (MOFs) containing porphyrin and Cu-porphyrin with anatase TiO 2 . The effect of the porphyrin metalation proportion was also investigated. Notably, while the use of free-base porphyrin as the organic linker resulted in the development of PCN-224, the presence of Cu-porphyrin provided mixed-phase MOF structures containing both PCN-224 and PCN-222. MOF/TiO 2 composites bearing partial (50%) metalated porphyrin were proven more active and selective towards the production of CH 4 , at ambient conditions, in the gas phase and using water vapors without the use of hole scavengers. The optimized composite bearing 15 wt.% of the partial metalated MOF was three times more active than pure TiO 2 towards CH 4 production. This study provides insights on the effect of precise materials engineering at a molecular level on the development of advanced MOF-based photocatalysts for CO 2 reduction.