Preparation Of TiO₂-BiVO₄ Heterojunction And Their Visible-light Photocatalytic Activity

As the water pollution is becoming more and more serious,the best way to deal with water pollution is photocatalysis technology. Looking for a kind of photocatalyst that has high photocatalytic activity becomes an advanced research hotspot. Bi VO4 with narrow band gap, is a widely studied photocatalyst due to its high visible-light photocatalytic activity. However, the recombination of photogenerated electron/holes affects the photocatalytic activity. Therefore, the modification of Bi VO4 becomes a hotspot for research. As a result, it is of great significance to synthesize Bi VO4-Ti O2 heterojunction due to its commercial application prospect.In this paper, Bi VO4 was prepared using hydrothermal method. In the hydrothermal system, NH4VO3 worked as the V source; Bi(NO3)3·5H2O worked as the Bi source; glucose worked as the surfactant; and Na OH worked as the p H regulator. After the process optimization, such as the temperature, time, p H value and the mass of surfactant, the as-prepared Bi VO4 showed a high photocatalytic activity in the degradation of Rh B under the irradiation of UV-vis light: after exposure for 120 min, 88% of the initial Rh B could be removed.In order to improve the photocatalytic property of Bi VO4, Ti O2 was used to modify Bi VO4, forming Bi VO4-Ti O2 heterojunction, which is beneficial for the separation of photon-generated carrier. In this thesis, Ti O2 precursor was firstly synthetized by adjusting the p H value, taking tetra-n-butyl titanate as titanium source, and water and ethanol as solvents. The as-prepared precursor was then mixed with Bi VO4 photocatalyst to obtain the heterogeneous Ti O2-Bi VO4 photocatalyst after heat treatment. The photocatalytic performance test indicates that Ti O2-Bi VO4 composite photocatalyst with heterojunction showed the best performance when the amount of Ti O2 is 6%. The removal rate of Rh B after 120 min reached 98%. Simultaneously, the photocatalytic mechanism of Ti O2-Bi VO4 composite photocatalyst with heterojunction illustrated that the formation of n-n type heterojunction between Ti O2 and Bi VO4 could effectively separate the photocatalytic carriers and further improve the photocatalytic activity.