Characterization of photocatalystsThe crystalline of photocatalysts was analyzed by RigakuM03XHF Ultima IV X-ray diffractometer (XRD) in the diffractionangle (2) between 10◦and 80◦, using Cu-K radiation as theX-ray source. The X-ray (wavelength = 1.5418 Å) tube equippedwith a copper target was operated at 40 mA and 40 kV. The UV–visabsorption spectrum of photocatalysts was measured by the UV–visspectrometer (Varian Cary-100) in the wavelength range between200 and 800 nm. Field emission scanning electron microscopy(FE-SEM) was carried out on a JEOL JSM-7000 FE-SEM. The pho-tocatalysts were sputtered with a thin layer of Pt film to preventsurface charging. The morphology of Pt/WO3photocatalyst wasobserved by Philips FEI Tecnai F20 G2high-resolution transmis-sion electron microscope (HR-TEM) at an acceleration voltage of200 kV. The specimen was prepared by ultrasonically dispersing thesample into ethanol, depositing droplets of the suspensions onto acopper mesh (200 meshes), and keeping 24 h in a vacuum dry oven(DOV30). For surface analysis, X-ray photoelectron spectroscopy(XPS) was conducted to identify the composition and chemical sta-tus of photocatalysts by the Theta Probe XPS (Thermo Scientific)with Mg target as the X-ray source of 1253.6 eV.