Study On TiO₂Powder Prepared By Dielectric Barrier Discharge At Atmospheric Pressure

Anatase TiO2as a semiconductor material, is widely used in solar cell, self-cleaning glass, water and air purification and sterilization etc. Dielectric barrier discharge(DBD) is typical nonequilibrium discharge at atmospheric pressure and is used to generate ozone at first. In recent years, articles about application of DBD in multifunction materials are extensive. In this paper, TiO2powder was prepared using TiCl4and O2through atmospheric pressure DBD.1. Electrodiagnosis and emission spectrum were detected with different gas flow rate, N2partial pressure, O2partial pressure, TiCl4partial pressure and input power. Voltage and charge of15kHz DBD were detected. Dielectric capacitance, gas capacitance and power factor were calculated and the variation of discharge parameters was studied in different gas flow rate, N2partial pressure, O2partial pressure, TiCl4partial pressure and input power. Emission spectrum of15kHz DBD and radio frequency DBD were detected. Ar excitation temperature and N2vibrational temperature were calculated by Boltzmann slope method. The variation of Ar excitation temperature was studied in different gas flow rate, N2partial pressure, O2partial pressure, TiCl4partial pressure and input power. The variation of N2vibrational temperature was studied in different gas flow rate, N2partial pressure, and input power. The results indicate that,15kHz DBD, dielectric capacitance deceases, gas capacitance and power factor keep invariant, Ar excitation temperature increases with increasing TiCl4partial pressure. Dielectric capacitance and power factor increase, gas capacitance keeps invariant, Ar excitation temperature increases firstly and then keeps invariant with increasing input power. Radio frequency DBD, Ar excitation temperature increases with increasing TiCl4partial pressure and increases firstly and then keeps invariant with increasing input power.2. Effects of different O2partial pressure, N2partial pressure, H2partial pressure and calcined temperature on TiO2powder prepared through radio frequency DBD were investigated. X-ray diffraction pattern shows that anatase characteristic peaks occur in samples prepared in different O2partial pressure, samples prepared in different N2partial pressure and samples prepared in different H2partial pressure. The grain size is distributed from12to21nm estimated by Debye-Scherrer formula. Ultraviolet visible absorption spectrum shows that absorption redshift increases with decreasing the O2partial pressure in samples prepared in different O2partial pressure. When the N2partial pressure is3.1kPa, the absorption redshift is most obvious for the samples prepared in different N2partial pressure. Absorption redshift increases obviously when the H2partial pressure is over stoichiometric ratio in samples prepared in different H2partial pressure. Fourier transform infrared spectrum shows that O2partial pressure is with no obvious effect on the surface OH content of samples prepared in different O2partial pressure. The existence of N2in discharge obviously decreases the content of surface OH. The OH content of samples prepared in different H2partial pressure increases with increasing H2partial pressure. X-ray photoelectron spectroscopy shows that the prepared TiO2powder is nitrogen doped and the relative surface content of N is3At.%. The photocatalytic evaluation of degrading methylene blue solution of samples calcined in different temperatures shows that photocatalytic activity of prepared TiO2powder decreases with increasing calcined temperature.