Oxygen vacancy-mediated WO3 nanosheets by etched {200} facets and the efficient visible-light photocatalytic oxygen evolution

Abstract

Constructing oxygen vacancies in a material surface is an effective strategy for improving the photocatalytic activity of catalysts. However, it is still a problem to prepare a catalyst containing a large amount of oxygen defects due to the harsh preparation conditions. In this study, ultrathin WO₃ nanosheets with abundant oxygen vacancies were fabricated through a facile etching process. Characterization by XPS spectra, EPR, VSM and TRPL tests revealed that substantial oxygen vacancies were produced in the etching process, which extended light absorption to the near-infrared region and effectively reduced the combination rate of photo-induced carriers. The presence of abundant oxygen vacancies resulted in approximately six-fold improvement in the photocatalytic O₂ evolution rate under simulated solar light illumination by the WO₃ nanosheets relative to that for their pristine counterparts. The quantum efficiency of O₂ evolution reached 15.3% under 420 nm light irradiation, which was much higher than that of the pristine WO₃ nanosheets.