Substitution effects of zinc porphyrin-sensitized TiO2 nanoparticles for photodegradation of AB1

Porphyrin-sensitized semiconductor particles can intensely absorb light in the visible wavelength range. Modification on molecular structure by either tuning the substituent species or elongating the distance between the second chromophore and porphyrin core may reduce interfacial electron-hole recombination and thus improving photocatalytic activity. Two zinc porphyrins are synthesized and doped on TiO 2 for photodegrading an organic pollutant AB1. Electronic structure of the molecules is studied by density functional theory calculations, showing more delocalized electron density on TPA-BiPh-ZnP than Cb-Ph-ZnP . Photo-electrochemical impedance measurements suggest greater electron-hole separation and interfacial charge transport efficiencies of TPA-BiPh-ZnP/TiO 2 than Cb-Ph-ZnP/TiO 2 . Both composites perform promising photodegradation activity of AB1, with superoxide radicals (•O 2− ) and holes (h + ) as the major reactive species at the reaction interfaces. Importantly, TPA-BiPh-ZnP/TiO 2 exhibits faster degradation kinetics than Cb-Ph-ZnP/TiO 2 , reaching a C/C 0 value of 10% within 60 min.