Novel Soft-Chemistry Route of Ag2Mo3O10 center dot 2H(2)O Nanowires and in Situ Photogeneration of a Ag@Ag2Mo3O10 center dot 2H(2)O Plasmonic Heterostructure
Résumé
Ultrathin Ag2Mo3O10*2H2O nanowires (NWs) were synthesized by soft chemistry under atmospheric pressure from a hybrid organic-inorganic polyoxometalate (CH3NH3)2[Mo7O22] and characterized by powder X-ray diffraction, DSC/TGA analyses, FT-IR and FT-Raman spectroscopies, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Their diameters are a few tens of nanometers and hence much thinner than that found for silver molybdates commonly obtained under hydrothermal conditions. The optical properties of Ag2Mo3O10*2H2O NWs before and after UV irradiation were investigated by UV-vis-NIR diffuse reflectance spectroscopy revealing, in addition to photoreduction of Mo6+ to Mo5+ cations, in situ photogeneration of well-dispersed silver Ag0 nanoparticles on the surface of the NWs. The resulting Ag@Ag2Mo3O10*2H2O heterostructure was confirmed by electron energy-loss spectroscopy (EELS), X-ray photoelectron spectroscopy (XPS), and Auger spectroscopy. Concomitant reduction of Mo6+ and Ag+ cations under UV excitation was discussed on the basis of electronic band structure calculations. The Ag@Ag2Mo3O10*2H2O nanocomposite is an efficient visible-light-driven plasmonic photocatalyst for degradation of Rhodamine B dye in aqueous solution.