Next Article in Journal
Effect of Both the Phase Composition and Modification Methods on Structural-Adsorption Parameters of Dispersed Silicas
Next Article in Special Issue
Wetting and Spreading of Commercially Available Aqueous Surfactants on Porous Materials
Previous Article in Journal
Systematic Characterization of DMPC/DHPC Self-Assemblies and Their Phase Behaviors in Aqueous Solution

Facile Fabrication of Multifunctional ZnO Urchins on Surfaces

School of Chemistry, University of Bristol, Cantock’s Close, Bristol BS8 1TS, UK
Centre for Nano Science and Engineering, Indian Institute of Science, Bangalore 560012, India
Bristol Centre for Functional Nanomaterials (BCFN), HH Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL, UK
Department of Biochemistry, Indian Institute of Science, Bangalore 560012, India
XMas, The UK CRG Beamline at the ESRF, The European Synchrotron, 71, avenue des Martyrs, CS 40220, 38043 Grenoble CEDEX 9, France
Department of Physics, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, UK
Bristol Dental School, University of Bristol, Bristol BS1 2LY, UK
Author to whom correspondence should be addressed.
Colloids Interfaces 2018, 2(4), 74;
Received: 19 November 2018 / Revised: 10 December 2018 / Accepted: 10 December 2018 / Published: 14 December 2018
(This article belongs to the Special Issue Wetting on Micro/Nano-Scale: From Fundamentals to Application)
Functional ZnO nanostructured surfaces are important in a wide range of applications. Here we report the simple fabrication of ZnO surface structures at near room temperature with morphology resembling that of sea urchins, with densely packed, μ m-long, tapered nanoneedles radiating from the urchin center. The ZnO urchin structures were successfully formed on several different substrates with high surface density and coverage, including silicon (Si), glass, polydimethylsiloxane (PDMS), and copper (Cu) sheets, as well as Si seeded with ZnO nanocrystals. Time-resolved SEM revealed growth kinetics of the ZnO nanostructures on Si, capturing the emergence of “infant” urchins at the early growth stage and subsequent progressive increases in the urchin nanoneedle length and density, whilst the spiky nanoneedle morphology was retained throughout the growth. ε -Zn(OH)2 orthorhombic crystals were also observed alongside the urchins. The crystal structures of the nanostructures at different growth times were confirmed by synchrotron X-ray diffraction measurements. On seeded Si substrates, a two-stage growth mechanism was identified, with a primary growth step of vertically aligned ZnO nanoneedle arrays preceding the secondary growth of the urchins atop the nanoneedle array. The antibacterial, anti-reflective, and wetting functionality of the ZnO urchins—with spiky nanoneedles and at high surface density—on Si substrates was demonstrated. First, bacteria colonization was found to be suppressed on the surface after 24 h incubation in gram-negative Escherichia coli (E. coli) culture, in contrast to control substrates (bare Si and Si sputtered with a 20 nm ZnO thin film). Secondly, the ZnO urchin surface, exhibiting superhydrophilic property with a water contact angle ~   0 ° , could be rendered superhydrophobic with a simple silanization step, characterized by an apparent water contact angle θ of 159° ± 1.4° and contact angle hysteresis Δ θ < 7°. The dynamic superhydrophobicity of the surface was demonstrated by the bouncing-off of a falling 10 μ L water droplet, with a contact time of 15.3 milliseconds (ms), captured using a high-speed camera. Thirdly, it was shown that the presence of dense spiky ZnO nanoneedles and urchins on the seeded Si substrate exhibited a reflectance R < 1% over the wavelength range λ = 200–800 nm. The ZnO urchins with a unique morphology fabricated via a simple route at room temperature, and readily implementable on different substrates, may be further exploited for multifunctional surfaces and product formulations. View Full-Text
Keywords: ZnO urchins; nanostructured surfaces; E. coli; superhydrophilic; superhydrophobic; anti-reflective surfaces ZnO urchins; nanostructured surfaces; E. coli; superhydrophilic; superhydrophobic; anti-reflective surfaces
Show Figures

Graphical abstract

MDPI and ACS Style

Tripathy, A.; Wąsik, P.; Sreedharan, S.; Nandi, D.; Bikondoa, O.; Su, B.; Sen, P.; Briscoe, W.H. Facile Fabrication of Multifunctional ZnO Urchins on Surfaces. Colloids Interfaces 2018, 2, 74.

AMA Style

Tripathy A, Wąsik P, Sreedharan S, Nandi D, Bikondoa O, Su B, Sen P, Briscoe WH. Facile Fabrication of Multifunctional ZnO Urchins on Surfaces. Colloids and Interfaces. 2018; 2(4):74.

Chicago/Turabian Style

Tripathy, Abinash, Patryk Wąsik, Syama Sreedharan, Dipankar Nandi, Oier Bikondoa, Bo Su, Prosenjit Sen, and Wuge H. Briscoe. 2018. "Facile Fabrication of Multifunctional ZnO Urchins on Surfaces" Colloids and Interfaces 2, no. 4: 74.

Find Other Styles
Note that from the first issue of 2016, MDPI journals use article numbers instead of page numbers. See further details here.

Article Access Map by Country/Region

Back to TopTop