Observable Vibronic Modes, Visible Luminescence, and Dewetting Response Mediated via Increased Roughness due to Splitting of WS2 Nanosheets by Energetic Xe+ Ions

Abstract

Herein, the hydrothermally derived, multilayered nanoscale WS2 subjected to 80 keV Xe+ ion irradiation with ion fluence varying in the range 1 × 1015–5 × 1016 ions cm−2 is reported. Transmission electron microscopy (TEM) imaging analysis reveals adequate splitting of stacks and consequent development of several layer sheets. Interestingly, the atomic force microscopy (AFM) studies exhibit several hillocks and craters in the postirradiated WS2, thereby enhancing the overall surface roughness (Rq) of specimens. Typically, Rq varies in the range 101–211 nm due to ion impact. This does not only influence the nature of visible emission features in the photoluminescence (PL) spectra but also Stoke's shift, suggesting strong electron–phonon coupling after radiation exposure. Moreover, Raman spectra of the studied systems reveal noticeable blue‐shifting of the Raman‐active E12g and A1g modes and also remarkable improvement in the E12g‐to‐A1g intensity ratio, ranging from 0.72 to 0.87. Finally, contact angle measurements carried out on specimen surfaces show a clear transition from the hydrophilic to hydrophobic behavior due to the irradiation‐induced increased surface roughness feature. The study can offer immense scope in components relevant to nano‐electromechanics, self‐cleaning, and nanocoatings and also where the switchable bifunctional property is invariably desired.