Nanoparticle Formation in Surface Layer of Oxide Materials and Improvement of Photocatalytic Properties of Rutile Titanium Dioxide

Abstract

Negative‐ion implantation could be used to create nanoparticles in oxide insulators with finely controlled accuracy for both depth and size. For 50‐nm‐thick SiO2 film on Si, Ag nanoparticles with 3 nm in diameter were created in the center of the film with distribution thickness of 17 nm. Cu negative‐ion implanted silica glass and soda‐lime glass showed a high nonlinear susceptance of the 3rd order in nonlinear optical property. Cu and Ag double‐implanted silica glass showed an absorption peak between two absorption peaks of surface plasmon resonance (SPR) for Cu and Ag nanoparticles. The optical absorption peak due to SPR of nanoparticle in oxide could be changed by forming nanoparticles with different kinds of elements and alloy. For application of metal nanoparticle to photocatalyst, Ag negative ions were implanted into rutile TiO2. The Ag‐implanted rutile samples showed improved photocatalytic efficiency after proper annealing in a decolorization test of methylene blue solution under fluorescent light. The better one was the Ag‐implanted rutile TiO2 (Ag: 65 keV, 5×1016 ions/cm2, 500°C annealed), which showed a photocatalytic efficiency higher by 2.2 times than that of unimplanted rutile TiO2. In the evaluation under fluorescent light through UV‐cut filter for 19 h, the Ag‐implanted rutile showed 6.7 times higher efficiency.