Integration of Copper(II)-Porphyrin Zirconium Metal–Organic Framework and Titanium Dioxide to Construct Z-Scheme System for Highly Improved Photocatalytic CO2 Reduction

Acquiring stable photocatalysts in possession of efficacious CO2 adsorption capacity and high charge-separation efficiency is crucial for carbon dioxide (CO2) photoreduction into fossil resources. Hereby, via a direct integration of copper(II)-porphyrin zirconium metal–organic framework (PCN-224(Cu)) and TiO2 nanoparticles, we establish an efficacious photocatalytic system capable of greatly enhancing the catalytic activity of TiO2 in CO2 photoreduction. In the absence of either cocatalyst or sacrifice reagent, CO evolution rate can reach up to 37.21 μmol g–1 h–1, ca. 10 and 45.4 times that of mere PCN-224(Cu) (3.72 μmol g–1 h–1) and pure TiO2 (0.82 μmol g–1 h–1), respectively. There are two contributors making devotion to the melioration of the catalytic activity. One is the augmented ability of light-harvesting given by the integrated metalloporphyrin-based MOF. The other is due to the conjunction between the MOF and TiO2, which constructs a Z-Scheme mechanism favoring beneficial promotion on the separation of photoexcited charges. This study provides theoretical support for meliorating photocatalytic performance through the combination of metalloporphyrin-based MOF and other inorganic semiconductors.