Improvement of photocatalytic efficiency of rutile titania by silver negative-ion implantation

Optical absorption and photocatalytic properties of metal negative-ion implanted rutile-type titania (TiO2) were studied to show metal nanoparticle formation in the surface region and improvement of photocatalytic efficiency. Silver negative ions were implanted into titania substrate (rutile crystalline substrate) at 65 keV with a dose of 3 x 1016-1 x 1017 ions/cm2. The Ag-implanted rutile also showed a strong optical absorption near 2.1 eV after annealing above 400 deg. C, those well agreed with theoretical absorption peaks due to surface plasmon resonance. This means that Ag nanoparticles were formed in the surface layers of the titania. Photocatalytic efficiencies for Ag-implanted titania were evaluated by means of decolorization of methylene blue solution under fluorescent light. Ag-implanted titania (Ag: 65 keV, 5 x 1016 ions/cm2, 500 deg. C annealed) showed the better photocatalytic efficiency higher 2.2 times than that of unimplanted rutile titania. In the evaluation under fluorescent light through UV-cut filter, the Ag-implanted rutile showed 6.7 times better efficiency