Effects of Electrodeposition Electrolyte Concentration on Microstructure, Optical Properties and Wettability of ZnO Nanorods

Abstract

ZnO nanorods were grown on ITO substrates with different concentration of electrolyte by electrodeposition method. Microstructure, surface topography, photoluminescence spectra, Raman spectra and water contact angle of the thin films were measured. The XRD results show all samples are hexagonal wurtzite and the intensity of diffraction peaks at (002) preferred orientation are strengthen as electrolyte concentration increase from 0.005 to 0.03 M. As the concentration increases, the average diameter, density and inclination of the ZnO nanorods increased. Room temperature photoluminescence spectras of the ZnO nanorods show a narrow UV band centering at about 377 nm and broad visible emissions around 600 nm and the UV peak intensity revealed a remarkable decreased. Raman spectras exhibit three peaks which are located at 439 cm −1 , 562 cm −1 and 1095 cm −1 . All samples change from hydrophobicity to hydrophilic after one hour ultraviolet (UV) irradiation. As an important wide bandgap (3.37 eV) semiconductor with a large exciton binding energy (60 meV), the wurtzite ZnO has triggered great interest in the past decade due to its great performance and potential applications in electro-optics, [23][24][25] and so on. Among the various growth methods, cathodic electrodeposition represents a rapid and cost-effective approach to the fabrication of ZnO thin films microstructures, which is widely used in the laboratory and industrial production.What's more, the wetting properties of ZnO thin films are very important from both fundamental and practical viewpoint. In recent years, ZnO thin films with special wetting properties have attracted much attention. Papadopoulou et al. 26 prepared hierarchically ZnO structures by irradiating silicon (Si) wafers with femtosecond laser pulses and subsequently coating them with ZnO by pulsed laser deposition. The ZnO thin films exhibit roughness at two length scales, and its surface wetting properties can be rapidly and reversibly switched between hydrophobicity and superhydrophilicity. He et al. 27 first put zinc foil oxidized in air and then deposited ZnO nanorods on zinc foil substrate by electrochemical deposition method, resulting in the formation of nanorods structures. The diameter of these nanorods are about 116 nm, and the films show an excellent superhydrophobicity. In this paper, ZnO nanorods were prepared within one step by cathodic electrodeposition method. In order to regulate the morphology of ZnO thin films, different amounts of Zn(NO 3 ) 2 •6H 2 O were added to the electrolyte. Microstructure, surface morphology and optical properties of the ZnO thin films were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), and microRaman spectroscope system. At last, wettability of the ZnO thin films and photoinduced hydrophilicity were tested through water contact angle apparatus. * Electrochemical Society Active Member.z E-mail: szq@ahu.edu.cn ExperimentalZnO thin films were prepared by three-electrode system, the electrochemical workstation (CHI600D) ...

Temporal wetting property of “Micro” versus “Nano” rods of ZnO grown using the pressure dependent aqueous solution method

“…Therefore, an oxygen-deficient surface will attract a water droplet, making the surface hydrophilic. 35,36 In our case, the PL analysis reveals that the intensity of the green emission of the nanorod (Fig. 4(c)) sample is at least one order of magnitude higher than that of the microrod sample (Fig.…”

Nanostructuring Effect of Nano-CeO2 Particles Reinforcing Cobalt Matrix during Electrocodeposition Process

“…Other authors [ 54 ] have also observed a decrease in the size of the matrix crystallites with an increase in the dispersed-phase concentration in the plating electrolyte.…”

“…The explanation for the decrease in the crystallite size of the cobalt matrix when increasing the dispersed-phase concentration in the plating electrolyte is as follows. The electrocrystallization or electrodeposition process is governed by two competitive steps: (i) nucleation site formation and (ii) crystal growth [ 54 ]. More nucleation sites will result in the reduced growth of the matrix crystallites.…”

“…By adding nano-CeO 2 particles in the plating electrolyte, more nucleation sites are formed on the substrate, which prevents the lateral and vertical growth of the cobalt crystallites. As a result, the average crystallite size decreases when the nano-CeO 2 concentration in the electrolyte increases [ 54 ].…”

“…This trend of a decrease in the contact angle with increasing current density has also been reported in the literature by other authors [ 55 ]. It is known that roughness is a key parameter that directly influences the wettability of surfaces [ 54 ].…”