Tuning ZnO Nanowire Dissolution by Electron Beam Modification of Surface Wetting Properties

The ability of modifying the surface properties plays a crucial role in nanostructures where the high surface-to-volume ratio is often exploited for a various range of applications. In this work, the anisotropic dissolution of ZnO nanowires (NWs) in water was analyzed, and a reversible method for the modification of the surface wetting properties based on electron beam irradiation was investigated. Using this approach, it was possible to selectively modify the wetting properties of single-crystalline ZnO NWs from hydrophilic to hydrophobic, preventing the degradation of these nanostructures when exposed to water. As deeply investigated by means of spectroscopic analyses, the switching mechanism of wettability was ascribed to the modification of organic compounds on the surface induced by electron beam irradiation. In particular, it was observed that the main effect of electron beam irradiation was to induce decomposition of hydrocarbons on the NW surface, with the consequent creation of radicals and reorganization of organic chains. In addition, we show that electron beam irradiation promotes the interaction of these nanostructures with an organic polymer (PMMA). The reversibility of the surface modifications was obtained by means of an oxygen plasma treatment that restored the initial hydrophilic properties of the nanostructures. The same principle could be exploited for controlling dissolution and avoiding corrosion of other nanostructures and films at the nanoscale.