Study On Hydrothermal Synthesis,Photocatalytic Properties Of The Bi₂WO₆ Nanosheets And The Self-assembled Bi₂WO₆ Nanostructures

Bi2WO6 with Bi-layer perovskite structure is an importantly visible-light-driven semiconductor photocatalyst,which has potential application prospects in utilizing solar energy to degrade organic pollutants and split water to prepare clean hydrogen energy.This paper makes an introduction of the mechanism and application of photocatalysis technology as well as common semiconductor photocatalysts and focuses on the research status of Bi2WO6 photocatalysts.On this basis,we discuss in detail the hydrothermal synthesis of single-crystal Bi2WO6 nanosheets and hierarchical flower-like Bi2WO6 sphere nanostructures in order to obtain Bi2WO6 photocatalysts with high photocatalytic activity.Finally,we applly the obtained Bi2WO6 photocatalysts to the photocatalytic degradation of rhodamine B and make a further research into their photocatalytic activities.The main results are summarized as following:1.The hierarchical flower-like Bi2WO6 sphere nanostructures self-assembled with nanosheets have been successfully synthesized by hydrothermal treating the aqueous suspension of Bi(NO3)3·5H2O and Na2WO4·2H2O without any minerallizers and surfactants.Based on the influence of hydrothermal reaction time on the phase and morphology evolution of-reaction products,we discuss and understand the formation mechanism of the hierarchical flower-like Bi2WO6 sphere nanostructures.2.Under alkalescent condition,the single-crystal Bi2WO6 nanosheets have been successfully synthesized by hydrothermal treating the aqueous suspension of Bi(NO3)3.5H2O or Bi(NH3)2C6H7O7·H2O and Na2WO4·2H2O.Based on the influence of hydrothermal reaction time and addition amount of NaOH on the phase and morphology evolution of reaction products,we understand the formation mechanism of the single-crystal B12WO6 nanosheets and controllably synthesise different single-crystal Bi2WO6 nanosheets with a thickness of ca.150 nm or 30 nm.3.Compared to the single-crystal Bi2WO6 nanosheets,the hierarchical flower-like Bi2WO6 sphere nanostructures exhibit more excellent visible-light photocatalytic activity,and it can completely degrade rhodamine B within 25 min under visible light irradiation.However,rhodamine B is completely degraded with the single-crystal Bi2WO6 nanosheets photocatalysts over 25 min.The different photocatalytic activities maybe attribute to that the hierarchical flower-like Bi2WO6 sphere nanostructures have a larger specific surface area and special mesoporous structures,which are beneficial to the absorption of visible light to motivate photoelectron and photohole.