Study On TiO₂ Films Prepared And Treated By Plasma At Low Pressure

TiO2 thin film is widely applied to air and water purification, self-cleaning and solar cells. There are many methods to prepare TiO2 thin films such as sol-gel method, physical vapor deposition and chemical vapor deposition method and so on. In this paper, room temperature, low-pressure plasma was applied to prepare TiO2 photocatalytic thin film on a glass substrate, besides the prepared films were treated by plasma. The experimental results are as follows:1. This paper has studied on discharge process by the electrical measurement and emission spectrum diagnosis. Discharge power along with the change of discharge parameters at Ar, Ar+O2, TTIP+Ar+O2. Research shows that:discharge power basically presents linear growth relationship with the increase of input power. There is making no difference of TTIP and O2 partial pressure on the discharge power, it is 3 W～4 W. The OES of these three discharge system, the experimental results that Ar atomic excitation temperature reduces with the increase of Ar flow rate, the same as O2 partial pressure at Ar+O2 and TTIP+Ar+O2 discharge, but it is increased and oxygen spectral line intensity increase in turn with input power increase.2. In this experiment, at room temperature, low-pressure plasma was applied to synthesize TiO2 thin films. Tetraisopropyl titanate (TTIP) was titanium source and oxygen was oxygen source. The influence of discharge conditions on the preparation of the photocatalytic activity of TiO2 was investigated. Within investigated range the results are as follows:with the O2 and TTIP partial pressure, input power and the deposition time increasing the photocatalytic activity of TiO2 film increases firstly and then decreases, FTIR spectra showed that the preparation of thin films contain OH functional groups, the hydroxyl content is consistent with the photocatalytic activity of thin films, the hydroxyl content increases, the photocatalytic activity enhances, this shows that OH is important factors affect activity of the films. UV-Vis absorption at 365 nm absorbance also is consistent with the TiO2 film of the photocatalytic activity.3. It is to select of a photocatalytic activity of the best conditions for the preparation of thin films after the experimental conditions investigation, then 450 ℃ calcination,N2 and O2 plasma treatment. The results show that the photocatalytic activity after thermal and N2 treatment has improved from 33% to 55% and its activity is essentially the same, after O2 treatment it is slightly decreased. After thermal and N2 plasma treatment, XRD spectra show that has faint characteristic peaks of anatase phase. Input power and processing time on the photocatalytic activity of TiO2 film presents first increase then remains unchanged trend. The results of OES show that rotational temperature increases from 350 K to 500 K, vibration temperature fluctuations from 4500 K to 4800 K.