Vacancy-Rich Monolayer BiO_2-x as a Highly Efficient UV, Visible, and Near-Infrared Responsive Photocatalyst

Vacancy-rich layered materials with good electron-transfer property are of great interest. Herein, a full-spectrum responsive vacancy-rich monolayer BiO_2-x has been synthesized. The increased density of states at the conduction band (CB) minimum in the monolayer BiO_2-x is responsible for the enhanced photon response and photo-absorption, which were confirmed by UV/Vis-NIR diffuse reflectance spectra (DRS) and photocurrent measurements. Compared to bulk BiO_2-x , monolayer BiO_2-x has exhibited enhanced photocatalytic performance for rhodamine B and phenol removal under UV, visible, and near-infrared light (NIR) irradiation, which can be attributed to the vacancy V_Bi-O ''' as confirmed by the positron annihilation spectra. The presence of V_Bi-O ''' defects in monolayer BiO_2-x promoted the separation of electrons and holes. This finding provides an atomic level understanding for developing highly efficient UV, visible, and NIR light responsive photocatalysts.