Effect of temperature on the morphology and optical properties of Ag2WO4 obtained by the co-precipitation method: Photocatalytic activity

In this work, Ag2WO4 was obtained at different co-precipitation temperatures (10, 30, 50, 70 e 90 degrees C). X-ray diffraction (XRD), X-ray fluorescence (XRF), field emission electron microscopy (SEM), chemical mapping, Xray photoelectron spectroscopy (XPS), Brunauer-Emmett-Teller method (BET) and spectroscopy in the ultraviolet region (UV-Vis) were used to characterize the Ag2WO4 particles. The photocatalytic and adsorbent activities were estimated by contact with methylene blue (MB) and methyl orange (MO) dyes. The Ag2WO4 obtained by the co-precipitation method presented monoclinic crystalline phase with nanorod morphology. The increase of the temperature favored the elongation and reduction of the thickness of the nanorods, which increased the surface area of the powders, favoring the photocatalytic and adsorptive activities. The high adsorption of the cationic molecules (MB dye), accompanied by the low anionic adsorption (MO dye), indicate the anionic character of the Ag2WO4 nanorods. In addition, the AW90 sample showed the best result in the reuse tests, where it lost only 5% of its efficiency in the fourth cycle.