Synthesis And Visible-light Photocatalytic Activity Of Bi₂mo₆(m=w, Mo)

Photocatalytic oxidation of organic pollutants has become a pollution control technology in recent years. In many photocatalyst, TiO2 is considered the best photocatalyst due to high photocatalytic activity, non-toxic, cheap property and so on. However, the application of TiO2 is limited because of its low quantum efficiency and narrow spectral response range. In order to find a higher visible light photocatalytic activity of the catalyst, some scholars utilize doping, sensitization, noble metal deposition and other measures to promote the range of TiO2.At the same time, some new visible-light catalyst was also prepared.visible-light catalyst Bi2WO6 and y-Bi2MoO6 were prepared by hydrothermal method, and the samples were characterized by XRD, SEM, DRS and other analytical tools. Using Rhodamine B as a degradation target, the photocatalytic activity of these catalyst was evaluated. Major research can be divided into two parts:Firstly, High purity and crystallinity Bi2W06 samples were prepared using bismuth nitrate (Bi (NO3)3·5H2O) and sodium tungstate (Na2WO4·2H2O) as raw materials by hydrothermal method under controlling reaction temperature, pH, and reaction time conditions. The optimum conditions were that reaction temperature was at 160℃, and reaction time was 24h at pH= 1.0. Experimental results showed that visible light catalyst can be an effective catalyst for degradation of rhodamine-B, and the catalytic activity depended on the size of the particle size and specific surface area. And after adding PVP, the crystal type of Bi2W06 didn't change, but the shape changed greatly. Formation of two different morphologies under the same conditions was mainly related with the PVP.Secondly, y-Bi2Mo06 nanocrystal was synthesized using bismuth nitrate (Bi (NO3) 3·5H2O) and ammonium ((NH4)6Mo7O24·4H2O) as raw materials by hydrothermal method. The results showed that y-Bi2Mo06 can also be synthesized under acidic condition, and the activity of y-Bi2Mo06 was significantly better than Bi2Mo06 obtained under neutral or weak alkaline conditions. Meantime all the samples formed mixed crystal under strong acid and alkali conditions. Through the photocatalytic degradation of Rhodamine-B dye, the best conditions for the hydrothermal synthesis y-Bi2Mo06 were determined.They were 140℃, and pH= 1.0. The Photocatalytic activity of Bi2Mo06 and y-Bi2Mo06 prepared under best conditions were compared. The catalytic activity of y-Bi2Mo06 was weaker than Bi2W06.The reason was that although the band gap of y-Bi2Mo06 was less than Bi2W06, its size and surface area were less than Bi2WO6 prepared under the same conditions.The article provides a certain foundation for research and application of layered perovskite structure photocatalyst responsed to visible light.