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.