Synthesis of an ultrathin MnO2 nanosheet-coated Bi2WO6 nanosheet as a heterojunction photocatalyst with enhanced photocatalytic activity

A MnO2/Bi2WO6 heterojunction photocatalyst was synthesized by simple hydrothermal method and characterized systematically. The results showed that ultrathin MnO2 nanosheets are evenly attached on the surface of Bi2WO6 nanosheets to form interfaces between MnO2 and Bi2WO6 and retains 3D flower-like structure of Bi2WO6. The MnO2 addition to Bi2WO6 increases the specific surface area, widens the light absorption region, and changes the electronic properties of Bi and W. Moreover, the defective Mn3+ increases oxygen vacancies and plays a rapid charge transfer role. A good energy band structure is formed in MnO2/Bi2WO6 to facilitate the photogenerated carrier separation. The photocatalytic studies suggest that MnO2/Bi2WO6 shows excellent photocatalytic efficiency and stability for the degradation of NO under light irradiation and inhibition for NO2 generation. MnO2/Bi2WO6 photocatalyst can produce more center dot OH and center dot O-2(-) radicals than Bi2WO6, and the electron transfer among Mn ions enhances the removal of NO.