Surfactant-Mediated Morphology and Photocatalytic Activity of α‑Ag2WO4 Material

• Published in: Journal of physical chemistry. C Vol. 122; no. 15; pp. 8667 - 8679
• Main Authors: Macedo, Nadia G, Gouveia, Amanda F, Roca, Roman A, Assis, Marcelo, Gracia, Lourdes, Andrés, Juan, Leite, Edson R, Longo, Elson
• Format: Journal Article
• Language: English
• Published: American Chemical Society 19.04.2018
• ISSN: 1932-7447; 1932-7455
• DOI: 10.1021/acs.jpcc.8b01898

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 analysis, Rietveld refinement analysis, Fourier-transform (FT) infrared spectroscopy, FT Raman spectroscopy, UV–vis spectroscopy, transmission electron microscopy (TEM), high-resolution TEM, selected area electron diffraction, energy-dispersive X-ray spectroscopy, field emission-scanning electron microscopy (FE-SEM), and photoluminescence emission, are employed to disclose the structural and electronic properties of the α-Ag2WO4 material. First-principles calculations were 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.