Electron-microscopic observation of photodeposited Pt on TiO2 particles in relation to photocatalytic activity
Abstract
We have shown that the shape and dispersion of photodeposited Pt on TiO2 particles are drastically changed by varying the sacrificial organic reagents present in aqueous solution. The Pt deposits were in good contact with TiO2 and showed oriented growth. Although the Pt deposits were distributed at random even around the steps at the surface without pretreatment, preillumination treatment caused preferential deposition on some terraces around the steps at the TiO2 surface. Induced lattice defects were observed by transmission electron microscopy near the TiO2 surface following photocatalytic reaction. The photocatalytic activity is closely related to the degree of Pt dispersion. The factor determining the degree of Pt dispersion is discussed, and a new model for photodeposition in solution is proposed.