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

摘要

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. (C) 2016 Elsevier Ltd. All rights reserved.