In situ construction of oxygen-vacancy-rich Bi0@Bi2WO6-x microspheres with enhanced visible light photocatalytic for NO removal

Abstract Surface oxygen vacancy defects and metal deposition on semiconductor photocatalysts play a critical role in photocatalytic reactions. In this work, oxygen-deficient Bi2WO6 microspheres have been prepared by a facile ethylene glycol-assisted solvothermal method. Bi0 nanoparticles were reduced by in situ thermal-treatment on Bi2WO6 microspheres to obtain Bi0@Bi2WO6-x as well as maintaining the oxygen vacancies (OVs) under N2 atmosphere. Afterwards, photocatalytic NO oxidation removal activities of these photocatalysts were investigated under visible light irradiation and Bi0@Bi2WO6-x shows the best NO removal activity than other samples. The photogenerated charge separation and transfer are promoted by Bi0 nanoparticles deposited on the surface of semiconductor catalysts. OVs defects promote the activation of reactants (H2O and O2), thereby enhancing the formation of the active substance. Moreover, both OVs defects and Bi0 metal have the characteristics of extending light absorption and enhancing the efficient utilization of solar energy. Besides, the photocatalytic NO oxidation mechanism of Bi0@Bi2WO6-x was investigated by in situ FTIR spectroscopy for reaction intermediates and final products. This work furnishes insight into the synthesis strategy and the underlying photocatalytic mechanism of the surface-modified Bi0@Bi2WO6-x composite for pollutants removal.