Research On The Effect Of Electric Field On The Photocatalytic Activity Of Titanium Dioxide Nano-membrane

To people's great interests, the technology of TiO2 photocatalysis oxygenation has been widely and potentially applied in administering environmental pollution, owing to its peculiarities such as the gentle reacting condition, easy and simple to handle, without secondary pollution and so on, which favor researchers much. However, the efficiency of TiO2 utilizing solar-power is much lower owing to the wider bandgap of TiO2 photocatalyst which can only be activated by shorter wavelength and upper energy of ultraviolet-light, furthermore, the catalytic activity of TiO2 photocatalyst is so low that it is hard to meet the requirement of practical application, because of the high composite rate of activated generant electrons and holes. Aiming at the problems existing on the technology of TiO2 photocatalysis oxygenation mentioned above, based on studying the mechanism of TiO2 photocatalysis and the structure of TiO2, the paper carried out several researches as below.(1)Adopting sol-gel method to prepare TiO2 nano-grain and nano-membrane, testing the samples to ascertain the form of the TiO2 crystal, the size of the grain, the thickness of membrane, by using the apparatus of XRD, UV-VIS spectrophotometer and so on.(2)The self-restrained photocatalytic reaction equipment with electric field was used, and the photocatalytic-electric oxidation treatment of dimethylbenzene, triethanolamine and methyl orange solution were studied with foam-nickel as radical material and adopting TiO2 nano-membrane prepared by sol-gel method and applying definite anode bias voltage to it. The polarity of bias voltage, the effect rule of the anode bias voltage and the initial solution concentration were investigated, and the difference of photocatalytic-electric and photocatalytic oxidation was compared. The results show that the degrading efficiency of organic pollutant could be raised greatly with the electric field of external anode bias voltage. The research on the apparent dynamics of the degrading of methyl orange showed the degradation of methyl orange photoelectrocatalysis conforms to apparent first-order reacting kinetic model.(3)The acting mechanism of electric field enhancing photocatalysis oxygenation activity was discussed, based on the theories of electrochemistry, semiconductor physics and quantum mechanics. The separation of photo-produced electrons and holes can be accelerated by the anode bias voltage applied on the semiconductor catalyst, and the photocurrent response and quantum efficiency are enhanced. The electric field can make the electron energy band of semiconductor incline, so electrons has more probability to penetrate through band-gap (potential barrier) to conduction-band when illuminated, and latent-optical-absorption occurs, therefore more photo-produced electrons and holes are made. Electric field on semiconductor brings Franz-Keldysh effect, the optical absorption side is widen, and light wave scope of occurring latent-optical-absorption become wider, so the utilizing efficiency of luminous energy is improved which is in favor of photocatalysis.