Electron transfer dynamics from the singlet and triplet excited states of meso-tetrakis(p-carboxyphenyl)porphyrin into colloidal TiO2 and AuTiO2 nanoparticles.

Electron transfer dynamics of meso-tetrakis(p-carboxyphenyl)porphyrin [TCPP] adsorbed on colloidal TiO(2) and AuTiO(2) nanoparticles have been investigated by time resolved absorption and fluorescence spectroscopy. Optical absorption studies reveal that the TCPP form complex with TiO(2) and AuTiO(2) nanoparticles. Excitation of TCPP adsorbed on the TiO(2) nanoparticle surface leads to electron injection on the conduction band of TiO(2). Electron injection has been confirmed by direct detection of cation radical of the adsorbed dye (TCPP*(+)). The rate constant for the electron injection process is determined from both the singlet and triplet state respectively. The rate of electron injection for TCPP-AuTiO(2) is much faster than TCPP-TiO(2). The injected electrons are quickly transferred to Au and it escorts to ignore the back electron transfer (recombination) process.