Catalyst-free synthesis of hydrophobic ZnO nanowires for self-cleaning applications

In this work, vertically aligned zinc oxide (ZnO) nanowires (NWs) were grown on silicon substrate using glancing angle deposition (GLAD) technique at an angle of 85°. Crystallinity and orientation of the as-deposited NWs were observed using X-ray diffraction (XRD) analysis. A strong peak along (002) plane was observed and the crystal size was calculated to be 65.83 nm. Scanning electron microscopy (SEM) revealed a rough morphological surface of the NW sample. Energy dispersive X-ray spectroscopy (EDX) determined the presence of Zn, O, and Si in the sample. Surface topography of the as-synthesized nanowire sample analyzed using atomic force microscope (AFM) deliver an average roughness of 22.47 nm. Using sessile drop method, the water contact angle (WCA) of the sample was measured to be 126° and found in excellent agreement with that of theoretical method. Thus, hydrophobic nature of ZnO NWs has been demonstrated which shows great potential in self-cleaning applications. (author)