关键词: 纳米TiO₂, 磷酸根, 金红石, 锐钛矿, 表面羟基密度

Abstract: Titanium dioxide was prepared by adding phosphate in the sol-gel process and acetic acid used as an inducer. The effect of phosphate on nano-titanium dioxide micro-structure and surface hydroxyl density were studied in this paper. The process of phase transition and surface structural change were investigated by powder X-ray diffraction(XRD),Brunauer–Emmett–Teller (BET),X-ray energy-dispersive (EDS),scanning electron microscope (SEM),fourier-transformed infrared (FT-IR) and thermogravimetric analysis (TGA). The results showed that the surface hydroxyl groups of nano-titanium dioxide were significantly increased with the adding amount of phosphate. The surface hydroxyl densities were 10.74nm^-2 and 4.03nm^-2 of the samples calcined at the temperature of 500℃ and 700℃,respectively. However,the control sample with none phosphate was 4.95 D_OH/nm² at 500℃. Moreover,the thermal stability of the phase transition was enhanced by adding phosphate in sol-gel process. Until the phase change temperature reached 800℃ did it have been begun to ransform anatase to rutile. The may be due to the bonding of PO₄^3- in these multidentate modes occupy one full face of [TiO₆] octahedra and inhibit the growing of chain along the opposite edges and hence inhibit the formation of rutile.

Key words: TiO₂ nanoparticle, phosphate, rutile, anatase, surface hydroxyl density