Generation of Oxygen Vacancy and OH Radicals: A Comparative Study of Bi2WO6 and Bi2WO6-x Nanoplates

A comparative study of visible-light-responsive Bi2WO6 and oxygen-deficient Bi2WO6-x nanoplates was conducted. The formation of oxygen vacancy resulted in the band gap narrowing of oxygen-deficient Bi2WO6-x, through an elevation of both of the conduction and valence band positions. FTIR spectra revealed that much more surface hydroxyl groups have been detected after the etching process. The scavengers tests confirmed the generation of OH radicals during photochemical reaction for Bi2WO6-x, whereas no (OH)-O-. radicals can be detected for pure Bi2WO6. The photocatalytic activities of optimized Bi2WO6-x on the decomposition of RhodamineB (RhB) was three times as high as that of pure Bi2WO6. The improvement of photocatalytic activity on degradation of RhB and phenol can be ascribed to the synergistic effect of oxygen deficiency-induced band shifts, together with the large quantities of surface hydroxyl groups providing active sites for the generation of OH radicals ((OH)-O-.).