Photocatalytic Reduction of Cr(VI) on a 3.0% Au/Sr(0.70)Ce(0.20)WO(4) Photocatalyst

[Image: see text] Herein, a 3.0%-Au/Sr(0.70)Ce(0.20)WO(4) sample was prepared for the photocatalytic reduction of the Cr(2)O(7)(2–) ion. The photocatalyst was characterized by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, and ultraviolet–visible diffuse reflectance spectra. The Sr(0.70)Ce(0.20)WO(4) sample presented a photocatalytic reduction activity that is better than those of the Ce-doped sample and the intrinsic sample. Thereafter, different metal elements, Cu, Ag, Au, and Pt, were used as cocatalysts, which were loaded on the Sr(0.70)Ce(0.20)WO(4) sample. The 3.0%-Au/Sr(0.70)Ce(0.20)WO(4) photocatalyst showed optimal photocatalytic reduction activity in a 8 vol % methanol solution (pH = 7) under visible light irradiation. The kinetic constant of the optimal one is 0.0039 min(–1), which is 1.86 times that of the Sr(0.70)Ce(0.20)WO(4) sample. The photocatalyst is stable enough after a 24 h photocatalytic experiment.