Efficient microwave hydrothermal preparation of nanocrystalline anatase TiO_2 colloids

摘要

Titanium dioxide nanocrystals are an important commercial product used primarily in white pigments and abrasives, however, more recently the anatase form of TiO_2 has become a major component in electrochemical and photoelectrochemical devices. An important property of titanium dioxide nanocrystals for electrical applications is the degree of crystallinity. Numerous preparation methods exist for the production of highly crystalline TiO_2 particles. The majority of these processes require long reaction times, high pressures and temperatures (450 -1400 deg C). Recently, hydrothermal treatment of colloidal TiO_2 suspensions has been shown to produce quality crystalline products at low temperatures (< 250 deg C). In this paper we extend this idea utilising a direct microwave heating source. A comparison between convection and microwave hydrothermal treatment of colloidal TiO_2 is presented. The resulting highly crystalline TiO_2 colloids were characcterised using Raman spectroscopy, XRD, TEM, and electron diffraction. The results show that the microwave treatment of colloidal TiO_2 gives comparable increases in crystallinity with resept to normal hydrothermal treatments while requiring significantly less time and energy than the hydrothermal convection treatment.