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Arsenene, a single-layer arsenic nanosheet with a honeycomb structure, has recently attracted increasing attention due to its numerous exceptional properties.

Abstract.This study presents an experimental approach for fabricating super-hydrophobic coatings based on a dual roughness structure composed of zinc oxide nanorod arrays coated with a sputtered zinc oxide nano-layer. The ZnO nanorod arrays were grown by mean of low-temperature electrochemical deposition technique (75°C) on FTO substrates with pre-sputtered ZnO seed layer of 30 nm thickness. The ZnO nanorods show a (002) orientation along the c-axis, and have a hexagonal structure, with an average length of 710 nm, and average width of 156 nm. On the other hand, the crystallite size of the top-coating sputtered ZnO layer is of 30 nm. The as-deposited ZnO nanorod arrays exhibited a hydrophobic behavior, with a surface water contact angle of 108°, whereas the dual-scale roughness ZnO nanorods coated with sputtered ZnO exhibited a superhydrophobic behavior, with a surface water contact angle of 157° and high water droplet adhesion. The photo-catalytic degradation of methylene blue in the presence of both the single roughness ZnO nanorod arrays, and dual roughness structured ZnO. The ZnO nanorod arrays showed good activity, with a degradation efficiency of 50% and a degradation constant of (k = 0.00225 min -1 ) after 5 hours of UV illumination. On the other hand, the ZnO dual roughness structure prepared by sputtered ZnO on top of the ZnO nanorod arrays showed minimal activity, with a degradation efficiency of 16% and a degradation constant of (k = 0.000586 min -1 ) after 5 hours of UV exposure. The double structured films exhibited high sensitivity to UV light, with a UV-induced switching behavior from super-hydrophobic to super-hydrophilic after only 30 minutes of UV exposure.Key Words: Super-hydrophobic, water contact angle, zinc oxide, nanorod arrays, rose petal effect, photo-catalysis. Highlights Hydrophobic ZnO nanorod arrays with high water-adhesion are achieved. Sputtered ZnO top-coating is used to reach super-hydrophobicity. Switchable wettability for ZnO single and dual roughness films under UV exposure. Strong pinning to the surface, similar to the rose-petal effect. The higher WCA is responsible for the decrease in the photo-catalysis activity.

We report results on the growth of an NaCl film on Ag(110) under ultrahigh vacuum conditions. At room temperature, low-energy electron diffraction and scanning tunneling microscopy show that the NaCl film forms a (4×1) superstructure. At RT, the film consists of small-sized islands that coalesce into larger islands at 410 K. These large islands preserve the (4×1) superstructure and cover the entire surface. The apparent heights obtained from the STM images show that the initial thickness of the NaCl islands is one atomic layer, and they present a very small height corrugation. The density functional theory calculations, with and without the inclusion of van der Waals effects, confirm the coexistence of two domains in agreement with the observed structure.

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