Visible-Light-Responsive Porphyrin-Incorporated TiO2 Treatment of Diatom Matrix

Abstract

In the present study, porphyrin-incorporated TiO2 was prepared and treated onto a diatom matrix by hydrothermal reaction. The photocatalytic activities under ultraviolet (UV, lambda = 365 nm) and light-emitting diode (LED, lambda > 420 nm wavelength) irradiation, along with the hydroxyl ((OH)-O-center dot) and superoxide (O-center dot(2)-) radical-generation mechanisms, was observed. The optimal TiO2 loading onto the diatom matrix (T-D) was found to include a Ti/Si ratio of 0.444 and a BET surface area of 39.65 m(2)/g. The porphyrin/T-D photocatalytic activities by UV- and LED-light irradiation for the Orange II dye solution showed optimal apparent rate constants in Fe(III) meso-tetra(4-carboxyphenyl) porphine chloride (Fe-TCPP)/T-D, as evidenced by (OH)-O-center dot and O-center dot(2)- radical detection according to the electron spin resonance (ESR)