Structure, optical properties, and photocatalytic activity of α-Ag2W0.75Mo0.25O4

Abstract

This article describes the synthesis of α-Ag2W0.75Mo0.25O4 using a coprecipitation method followed by microwave irradiation for different times. The samples were characterized using X-ray and neutron diffractions with Rietveld refinement, Raman spectroscopy, X-ray fluorescence, and ultraviolet-visible diffused reflectance spectroscopy, as well as by photoluminescence emissions. To complement and rationalize the experimental results, first-principles calculations were performed. The formation and growth of metallic Ag nanoparticles on the surfaces of α-Ag2W0.75Mo0.25O4 were studied by transmission electron microscopy and energy dispersive X-ray spectroscopy. Results show that α-Ag2W0.75Mo0.25O4 samples obtained correspond to α-Ag2WO4/β-Ag2MoO4 heterostructure, and the posterior microwave irradiation favors the process of substituting W by Mo, with subsequent formation of a solid solution. Photocatalytic tests were performed to verify the photocatalytic efficiency against the Rhodamine B. Photoluminescence emissions and photocatalytic results showed that the samples obtained at the longest microwave irradiation time promoted the formation of structural defects and enhanced the material properties