Regulation of the band structure and water solubility of perylene imide derivatives based on bay-substitution to accelerate the transport of photogenerated carriers with TiO2

Abstract

Improving the efficiency of photogenerated charge separation and transport is the primary goal of designing and constructing efficient composite photocatalysts. The matching of energy bands and the formation of chemical bond between the two components are very conducive to the separation and transmission of photogenerated charges. Herein, three perylene diimide derivatives (PDIs) are synthesized by introducing sulfonic acid group (PDI-SA) and benzenesulfonic acid (PDI-BSA) respectively into the amide bond and further chlorine bay-substituting (Cl-PDI-BSA). The good water solubility of Cl-PDI-BSA ensures its forms a stable chemical bond with TiO2 through the sulfonic acid group in the single molecular state, coupled with the matching of energy band structure, TiO2@Cl-PDI-BSA exhibited excellent performance upon visible light photocatalytic degradation to phenol and trenbolone acetate (TBA). It can remove 100% of phenol in 15 min and 100% trenbolone acetate (TBA) in 30 min, which is 14.3 times that of TiO2. Combining to DFT calculation, Kelvin probe force microscope and EPR analysis prove that bay chlorine substitution has a greater impact on the energy band structure and electron cloud distribution of PDIs than N-sulfonation, thereby seriously affecting the transport of photogenerated carriers with TiO2.