The highly efficient and stable Cu, Co, Zn-porphyrin–TiO2 photocatalysts with heterojunction by using fashioned one-step method

Abstract

A new series of carboxyl porphyrins with different center metals (Cu, Co, Zn) insertion has been successfully synthesized. Their corresponding CuCPp–TiO2, CoCPp–TiO2, and ZnCPp–TiO2 photocatalysts were obtained under a one-pot solvothermal condition. Characterization of these composites can be achieved by both spectroscopic techniques and nitrogen adsorption–desorption measurements. The findings indicate that the MCPp–TiO2 (M(II) = Cu, Co, Zn) composite photocatalysts, formed by the accumulation of disperse spherical nanoparticles, possess heterogeneous structure and large surface area, resulting in the photodegradation of 4-nitrophenol (4-NP) efficiently. The metalloporphyrins with carboxyl group display superior catalytic activities due to the strong interactions between COOH and TiO2. The order for the photocatalytic activities is as follows: CuCPp–TiO2 > CoCPp–TiO2 ≥ ZnCPp–TiO2 > bare TiO2. The reason for the high photocatalytic activity in CuCPp–TiO2 photocatalyst can possibly be explained by the fact that Cu(II) is more readily gaining an electron to reach a steady state, causing the isolation of electrons with holes compare to Co(II) and Zn(II) in MCPp–TiO2 composites. This possible mechanism of photocatalytic efficiencies was proposed based on the multiple tests. The findings of MCPp–TiO2 photocatalysts tests suggested that the metalloporphyrin-based MCPp–TiO2 composite photocatalysts are capable of maintaining superior stability in photocatalysis experiments even after six times cycling.