Photoinduced electron transfer reactions between meso-tetrakis(4-sulfonatophenyl)porphyrin and colloidal metal-semiconductor nanoparticles

Abstract

The dynamics of photoinduced electron transfer between meso-tetrakis(4-sulfonatophenyl)porphyrin [TSPP] and colloidal metal-semiconductor nanoparticles (AgTiO 2 and AuTiO 2) have been studied by using absorption, infra-red, steady state and time resolved fluorescence spectroscopic measurements. The apparent association constant ( K app) deduced using Benesi–Hildebrand equation from the absorption spectral changes for TSPP-colloidal AuTiO 2 nanoparticles (24.69 × 10 4 M −1) was higher than colloidal TiO 2 nanoparticles (4.78 × 10 4 M −1). Lifetime measurements shows higher rate of electron transfer for colloidal AuTiO 2 nanoparticles (4.56 × 10 8 s −1) compared to colloidal TiO 2 nanoparticles (2.54 × 10 8 s −1). The electron transfer mechanism was explained based on the Rehm–Weller equation as well as the energy level diagram. The electrons injected into the TiO 2 were quickly transferred to the metal core. Use of metal-semiconductor nanoparticles may provide new ways to modulate charge recombination processes in dye-sensitized solar cells.