PHOTOSTABILIZATION OF ORGANIC-DYES ON POLY(STYRENESULFONATE)-CAPPED TIO2 NANOPARTICLES

Photostabilization of phenosafranin dye on poly(styrenesulfonate)-capp ed TiO2 nanoparticles has been investigated using diffuse reflectance spectroscopy. The dye degrades oxidiatively on a native TiO2 surface u nder visible light excitation as the excited dye participates in the c harge injection process. The interaction of the dye with the semicondu ctor surface can be significantly reduced by capping the TiO2 particle s first with poly(styrenesulfonate). The increase in fluorescence emis sion and decrease in dye degradation rate with increasing polymer capp ing suggest the protective role of poly(styrenesulfonate) capping. Dif fuse reflectance laser flash photolysis studies further elucidate surf ace photochemical processes of phenosafranin on native and polymer-cap ped TiO2 nanoparticles.