Silver negative-ion implantation to sol-gel TiO2 film for improving photocatalytic property under fluorescent light

We have investigated improvement of photocatalytic properties of spin-coated sol-gel anatase-type TiO2 with a bandgap of 3.2 eV by negative ion-implantation. Silver-negative ions were implanted to anatase-type sol-gel TiO2 films (about 500 nm in thickness) on a glass at 65 and 30 keV with various doses in 1016-1017 ions/cm2. Subsequent annealing was performed at up to 600 °C for 1 h. After annealing at above 300 °C, all the samples showed strong optical absorption of surface plasmon resonance of Ag nanoparticles at around the photon energy of 2.2 eV. This means that Ag nanoparticles were formed in the TiO2 films. In the photocatalytic properties under fluorescent light, the Ag-implanted sample (30 keV, 1 × 1016 ions/cm2) after annealing at 400 °C showed an improved photocatalytic efficiency by 1.58 times than a rutile single crystal TiO2 with bandgap of 3.0 eV less than that of the anatase. Ag nanoparticles formed at shallower depth are considered to work well for catalysis.