Synthesis of superhydrophobic ZnO micro-rods on carbon cloth

Carbon cloth (CC) was coated with ZnO micro-rod modified with stearic acid (SA) in order to obtain superhydrophobic properties. The prepared sample shows watercontact angle (WCA) of 160o. In recent years, solid surfaces with superhydrophobic property which display high contact angle (θ > 150°) have attracted great worldwide attention [1] because of their wide applications, including self-cleaning and numerous potential applications [2]. At first the surface of carbon cloth was oxidized with KMnO4 aqueous solution. The ZnO micro rods were hydrothermally deposited on the carbon cloth by dipping into the mixture composed of aqueous solution zinc nitrate, hexamethylenetetramine and NH4OH in a Teflon lined stainless steel autoclave and then heating at 180℃ for 6h.The as prepared ZnO micro-rod on carbon cloth was immersed into an ethanol solution of stearic acid to obtain the superhydrophobic CC/ZnO/SA. The prepared sample was characterized by scanning electron microscopy (SEM), Xray diffraction (XRD), Fourier transform infrared spectra (FTIR), attenuated total reflectance Fourier-transform infrared spectroscopy (ATR-FTIR) and contact angle measurements. As shown in (Fig 1a) the CC/ZnO exhibits surface hydrophobicity with water contact angle of 98ᵒ. But the sample becomes superhydrophobic after treatment with stearic acid and the contact angle increased from 98˚ to 160˚ (Fig 1b). The effect of solution pH on the wettability of CC/ZnO/SA is shown in Fig 1c. It is clear that the prepared sample is not wetted by the aqueous solutions with different pH values.To demonstrate the self-cleaning ability of the superhydrophobic surface, the pristine carbon cloth and the fabricated superhydrophobic CC/ZnO/SA were both contaminated with soil. When water droplets dropped on the surface, they quickly penetrated in the pristine hydrophilic carbon cloth and most of the soil remain on the surface. Comparatively, most of soil powder was clearly removed with water droplets rolling off the superhydrophobic CC/ZnO/SA, exhibiting excellent self-cleaning property.