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

• Published in: Applied surface science Vol. 258; no. 20; pp. 8146 - 8152
• Main Authors: KHRANOVSKYY, V, EKBLAD, T, YAKIMOVA, R, HULTMAN, L
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier 01.08.2012
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Contact angle; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Morphology; Nanocomposites; Nanomaterials; Nanostructure; Physics; Semiconductors; TECHNOLOGY; TEKNIKVETENSKAP; Wettability; Zinc oxide; Wettability; Ultraviolet radiation; Inorganic compounds; Hydrophilicity; Transition element compounds; Zinc oxide; ZnO nanostructures; UV irradiation; Nanostructures; Hydrophobicity; Surface structure
• ISSN: 0169-4332; 1873-5584; 1873-5584
• DOI: 10.1016/j.apsusc.2012.05.011

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 degree ) 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.