Tunable and reversible surface wettability transition of vertically aligned ZnO nanorod arrays

Das, Sachindranath; Choi, Jong Bo; Kar, Jyoti Prakash; Myoung, Jae Min

doi:10.1016/j.apsusc.2009.03.090

Cited by 52 publications

(32 citation statements)

References 21 publications

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“…The dependence of hyrophobicity of the film on its structure has been explained in terms of the amount of air got trapped within the interstices of the rough surface. The trapped air pressure balances the gravity, and the surface tension of the water is responsible for keeping the shape of the droplet as spherical [54]. The film with high volume of air effectively prevents the penetration of water droplets into the grooves, thereby giving rise to hydrophobicity.…”

Section: Wettability Studiesmentioning

confidence: 99%

Effect of Sn doping on structural, optical, electrical and wettability properties of oriented ZnO nanorod arrays

Kumar

Nagaraja

2013

J Mater Sci: Mater Electron

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Herein we present a modified sol gel route for the one step fabrication of oriented ZnO nanorod arrays. The method is seed layer free, and nanorods directly attach to a substrate. We also present the effect of tin (Sn) content on the crystallinity, microstructural, optical and electrical properties of the ZnO nanorod arrays. Thermo gravimetric (TG) curves of gel precursors showed that most of the organic groups and other volatiles were removed at about 450°C. X-ray diffraction patterns confirmed that the films were polycrystalline in nature with (002) preferred orientation. The texture coefficient, grain size, dislocation density and lattice parameters of the ZnO arrays were determined. The SEM micrographs revealed that the undoped and 1 at.%Sn doped films were composed of nanorods and the concentration of 2 at.%Sn doping hindered the rod like structure growth and modulated into granular nature. UVvisible transmission spectroscopy indicated that the transparency of the films increased with Sn content. On Sn doping, the films also exhibited a red shift and slight shrinkage of band gap. The electrical studies revealed that 1 at.% of Sn doping enhanced electrical conduction in ZnO films and beyond that the distortion caused in the lattice reduced the conductivity. The contact angle of the ZnO nanostructures varied between 91°and 115°depending upon the Sn content. Therefore, 1 at.%Sn doping into ZnO nanorods improves the crystallinity, electrical conductivity and water contact angle.

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Section: Wettability Studiesmentioning

confidence: 99%

Effect of Sn doping on structural, optical, electrical and wettability properties of oriented ZnO nanorod arrays

Kumar

Nagaraja

2013

J Mater Sci: Mater Electron

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“…ZnO has a large family of nanostructures; differing in shape, size and arrangement, including rods, pillars, wires, needles, belts, springs tetrapods etc [13 -16]. Earlier, a number of studies were reported on the wettability of ZnO structures of different morphology: films [2 -6], nanorods [7 -10], nanoneedles [8], nanonails [8], and hierarchical structures [11,12]. Since the wettability processes are surface mediated the nanostructures demonstrated more advanced wettability features, due to their highly developed surface.…”

Section: Introductionmentioning

confidence: 99%

Surface morphology effects on the light-controlled wettability of ZnO nanostructures

Khranovskyy

Ekblad

Yakimova

et al. 2012

Applied Surface Science

112

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ZnO nanostructures of diverse morphology with shapes of corrals and cabbages as well as open and filled hexagons and sheaves prepared by APMOCVD technique, are investigated with water contact angle (CA) analysis. The as-grown ZnO nanostructures exhibit pure hydrophobic behavior, which is enhanced with the increase of the nanostructure's surface area. The most hydrophobic structures (CA = 124°) were found to be the complex nanosheaf, containing both the macro-and nanoscale features. It is concluded that the nanoscale roughness contributes significantly to the hydrophobicity increase. The character of wettability was possible to switch from hydrophobic to superhydrophilic state upon ultra violet irradiation. Both the rate and amplitude of the contact angle depend on the characteristic size of nanostructure. The observed effect is explained due to the semiconductor properties of zinc oxide enhanced by increased surface chemistry effect in nanostructures.

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“…Subsequently, the ZnO surface evolves back to its original state after storage in dark. Das et al (2009) reported that it took about 4 min for ZnO nanoneedles, around 7 min for ZnO nanonails for contact angle transition from hydrophobic to hydrophilic. It implies that the transition time is perhaps related with crystal morphology.…”

Section: Resultsmentioning

confidence: 99%

“…Recently, the manipulation of the light-induced wettability changes of inorganic oxide (such as ZnO, TiO 2 ) films have been investigated (Feng et al, 2004;Caputo et al, 2008Caputo et al, , 2009aDas et al, 2009;Papsdopoulou et al, 2009). Feng et al (2004 found that reversible super-hydrophobicity to super-hydrophilicity transition was observed and controlled by alternation of UV irradiation and dark storage on aligned ZnO nanorod films.…”

Section: Introductionmentioning

confidence: 99%

Wettability of porous two‐dimensional ZnO nanocrystal films

et al. 2011

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Large-scale two-dimensional ZnO nanocrystal films on aluminum substrate were fabricated by a one-step hydrothermal method under mild conditions, where all the ZnO nanocrystals had a lamellar structure generally perpendicular to the substrates and formed network-like porous configurations. The morphologies of the films were dependent on both the reaction temperature and concentration of zinc. The wettability of the ZnO films was assessed by measuring the water contact angle without any surface functionalisation. The porous structures of the as-prepared films could effectively enhance its hydrophobicity and the water contact angle ranged from 40 • to 135 • depending on the surface morphology and the arrangement of ZnO planes, indicating a simple and promising route to make aluminum surface waterproof and even self-cleaning. The hydrophobic ZnO surface could be switched to hydrophilic state by UV irradiation.A grandeéchelle films nanocristaux de ZnOà deux dimensions sur substrat d'aluminium ontété fabriquées par un procédé hydrothermal en uné etape dans des conditions douces, où tous les nanocristaux de ZnO ont une structure lamellaire généralement perpendiculaire aux substrats et formé des configurations poreux de type réseau. Les morphologies des films dépendentà la fois la température de réaction et la concentration de zinc. La mouillabilité des films de ZnO aétéévaluée en mesurant l'angle de contact de l'eau sans la fonctionnalisation de surface. Les structures poreuses des films pourrait effectivement augmenter l'hydrophobie et l'angle de contact de l'eau variait de 40à 135 • en fonction de la morphologie de surface et l'arrangement des plans de ZnO, indiquant une route simple et promettant de faire surface en aluminium imperméable et même auto-nettoyant. La surface hydrophobe de ZnO pouvaientêtre transformés enétat hydrophile par irradiation UV.

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Tunable and reversible surface wettability transition of vertically aligned ZnO nanorod arrays

Cited by 52 publications

References 21 publications

Effect of Sn doping on structural, optical, electrical and wettability properties of oriented ZnO nanorod arrays

Effect of Sn doping on structural, optical, electrical and wettability properties of oriented ZnO nanorod arrays

Surface morphology effects on the light-controlled wettability of ZnO nanostructures

Wettability of porous two‐dimensional ZnO nanocrystal films

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