Efficient Photoinduced Electron Transfer Using TiO2 Doped Polymer

Nanoparticles of TiO2 were prepared by sol-gel method and fixed onto the surface of a quartz plate by the layer-by-layer method using poly (diallyldimethylammonium chloride) and potassium polyvinyl sulfate. This TiO2/polymer film was employed for dihydronicotinamide adenine dinucleotide (NADH) production from NAD(+) with lipoamide dehydrogenase and methyl viologen in Tris-HCl buffer on irradiation with UV light. The ultra thin film prevented the enzyme from deactivating. In order to enhance the reduction of viologen (V), cavities for molecular recognition of V were fabricated on the surface of TiO2 through a sol-gel imprinting method. The TiO2 had recognition site for the oxidized viologen (V2+) on its surface, which was distinguishable through shape or charge differences from the reduced viologen (V+center dot). This facilitated the inclusion of V2+ and resulted in an enhancement of the photo-induced reduction. Also, electrospun TiO2 nanofibers were prepared and applied for hydrogen evolution. After calcination at 450 degrees C for 3 h, a highly active sample was obtained because of relatively higher crystallinity, and larger surface area as compared with other nanofibers and commercially available nanoparticles.