Study On Preparation Of N, F-codoped TiO₂Films And Photocatalytic Activity Under Visible Light

Titanium dioxide （TiO₂） has been extensively studied through the world andconsidered as reference photocatalyst in the degradation of organic pollutants,sewage treatment, air purification, disinfection due to its superior photocatalyticperformance, nonselective degradation of various organics, deep mineralization rate,low cost, inert and non-toxic properties.However, the pure TiO₂with energy band gap of3.2eV exhibits spectralresponse only in UV region, which limits the practical applications due to the poorutilization of solar lights. At the same time, due to the higher recombination rate ofphotocarrier and low quantum efficiency, the photocatalytic efficiency of TiO₂wasalso influenced. Therefore, considerable effort has been made to increase theabsorption of TiO₂in the visible region to improve its visible light response throughvarious surface modifications such as doping of various metal or nonmetal oxides.In this paper, N,F-codoped TiO₂film, La,N,F-codoped TiO₂film,Fe,N,F-codoped TiO₂film and Co,N,F-codoped TiO₂film photocatalysts withsol-gel method at room temperature were proposed. A series of photocatalyticdegradation experiments were carried out under visible light irradiation in thepresence of doped TiO₂films, which using acid red B and Methylene blue trihydrateas model compounds. Also, some influence factors like heat-treatment temperatureand number of film on the photocatalytic activities of the prepared TiO₂photocatalysts, and irradiation time, light power, initial concentration, and solutionpH on the photocatalytic degradation of acid red B and Methylene blue trihydratewere assessed in detail by UV–vis spectra and ion chromatography.Theexperimental results proved that, to begin with, the photocatalytic activity ofN,F-TiO₂film is better than that of N-TiO₂film or F-TiO₂film. Degradation rate of10mg/L acid red B is up to98.5%in the presence of N,F-TiO₂film for30hourirradiation under the visible light. Secondly, the photocatalytic activity ofLa,N,F-TiO₂film is better than that of N,F-TiO₂film. Degradation rate of10mg/L acid red B is up to100%in the presence of La,N,F-TiO₂film for30hour irradiationunder the visible light. Lastly, the photocatalytic activity of Fe,N,F-TiO₂film isbetter than that of Co,N,F-TiO₂film. Degradation rate of10mg/L Methylene bluetrihydrate is up to100%and98.6%which respectively in the presence ofFe,N,F-TiO₂film and Co,N,F-TiO₂film for12hour irradiation under the visiblelight.