W+6/W+5 redox reactions at the interface of the nanocrystalline TiO2 photoactive electrode

Photocurrent of nanocrystalline TiO₂ thin films has been probed by using a steady-state photoconduction technique. A broad single peak (280-410 nm) photocurrent spectrum was observed for the TiO ₂ thin films. The photocurrent maximum at about 360 nm associates with the direct band gap of anatase TiO₂. The electron-hole pair formation that occurs at the interface between semiconductor TiO₂ nanoparticles and a solution upon absorption of near UV light leads to redox reactions of solution species (W⁺⁶/W⁺⁵). The mechanism of such photodriven processes are discussed along with the potential applications in photoelectrochemical cells and as particulate photochromic systems