Surfactant-Mediated Morphology and Photocatalytic Activity of α-Ag2WO4 Material
Abstract: In the present work, the morphology (hexagonal rod-like vs. cuboid-like) of an α-Ag2WO4 solid-state material is manipulated by a simple controlled-precipitation method, with and without the presence of the anionic surfactant sodium dodecyl sulfate (SDS), respectively, over short reaction times. Characterization techniques, such as X-ray diffraction (XRD) analysis, Rietveld refinement analysis, Fourier-transform infrared (FT-IR) spectroscopy, Fourier-transform Raman (FT-Raman) spectroscopy, UV-Vis spectroscopy, transmission electron microscopy (TEM), high resolution-transmission electron microscopy (HR-TEM), selected area electron diffraction (SAED), energy-dispersive x-Ray spectroscopy (EDS), field emission-scanning electron microscope (FE-SEM), and photoluminescence emission, are employed to disclose the structural and electronic properties of the α-Ag2WO4 material. First-principles calculations have been performed to: i) obtain the relative stability of the six low-index surfaces of α-Ag2WO4; ii) rationalize the crystal morphologies observed in FE-SEM images (using the Wulff construction); and iii) determine the energy profiles associated with the transformation process between both morphologies induced by the presence of SDS. Finally, we demonstrate a relationship between morphology and photocatalytic activity, evaluated by photodegradation of Rhodamine B dye under UV light, based on the different numbers of unsaturated superficial Ag and W cations (local coordination, i.e. clusters) of each surface.
