Preparation Of N-TiO₂/ITO And Its Photocatalytic Performance

The TiO₂ photocatalytic oxidation technology has received extensive attention in recent years as an environmentally friendly deep purification technology for organic pollutants.Although this technology has great advantages in the degradation of refractory contaminants compared to common physics,chemistry,and biotechnology,a large number of studies have found that there are several problems that restrict its further development in photocatalytic technology,such as the catalyst powder is easy to lose;the light response range is narrow;the electron-hole recombination rate is high.To solve those problems,the structure of TiO₂ photocatalyst and its related mechanism of photocatalysis have been studied.The paper studied in four aspects.?1?N-TiO₂/ITO was prepared by sol-gel method.Photocatalytic degradation of Methylene Blue in visible-light was carried out by different catalyst created by three factors including calcining temperature,sol-gel pH and N-doped.Based on the single factor experiment,Design-Expert 8.0 software was used to design a three-factor and three-level response surface scheme.According to the model,the optimal catalyst preparation conditions were calcination temperature of 486.79?,N-doped of 1.02 g,and sol pH of 6.96,in these conditions,the predictive degardation rate in 6 hours can reach 75.63%.?2?To investigate the effect of the preparation conditions on the morphology,crystal structure,and absorption spectra of the catalyst,SEM,XRD and DRS were used to characterize the catalysts prepared under different preparation conditions.?3?Photocatalysis studies were carried out by optimized N-TiO₂/ITO under three different water quality reaction conditions:initial concentration of methylene blue,solution pH,and NaCl concentration.The effect of different photocatalytic reaction conditions on the photocatalytic degradation rate was explored through a single-factor experiment,and a three-factor and three-level response surface scheme was designed on this basis.Then analyse experimental results by ANOVA,contour plots and 3D plot.The optimal reaction conditions under this catalyst were the initial solution concentration of 9.39 mg/L,the solution pH of 8.44,and the NaCl concentration of 0.40g/L,in these conditions,the predictive degardation rate in 4 hours can reach 64.12%.Under the optimal preparation conditions and optimal reaction conditions of the catalyst,the photocatalytic performance under ultraviolet light and sunlight was tested respectively.The results showed that the nitrogen doping did not affect the catalytic effect under ultraviolet light,and it could also obtain better catalytic effect under sunlight.?4?The electro-assisted photocatalytic oxidation was studied with N-TiO₂/ITO as the anode and graphite as the cathode.Compared with electro-oxidation and photocatalytic degradation under the same solution conditions and catalyst,the additional enhancement effect of applied voltage on pure photocatalysis was found.All three processes conform to the pseudo-first-order reaction kinetics,and the rate constant under the electro-assisted photocatalytic process is three-fold that of photocatalytic alone.The effects of initial concentration of methylene blue,solution pH and external anode bias voltage on the photocatalytic degradation rate of electro-assisted photocatalysis were investigated by single-factor experiments.Different from the single photocatalytic reaction,electro-assisted photocatalysis exerts higher performance when dealing with higher concentration of pollutants.and the catalytic performance is higher under neutral and acidic acid solution pH conditions.