| The wurtzite ZnO has triggered great interest in the past decade, it has wide band gap (3.37 eV), large exciton binding energy (60 meV), and get a great performance and potential applications in lectro-optics[1-3], ferroelectric [3], pyroelectricity and piezoelectricity [4-5], catalysis [6], and sensors [7]. According to different particle shape, size, crystal structure, crystal form and applications. 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. In this paper, ZnO thin films were prepared within one step by cathodic electrodeposition method. Microstructure, surface morphology, optical properties, photocatalytic activitivies and wettability of the ZnO thin films were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), ultraviolet-visible spectroscope (UV-Vis), micro-Raman spectroscope system and water contact angle apparatus.The results show that different electrolyte concentration in cathodic electrodeposition could prepare various ZnO thin films different in microstructure, surface morphology, optical properties, photocatalytic activitivies and wettability, when electrodeposition voltage, time and bath temperature is fixed. The result of XRD show that all ZnO thin films prepared in different electrolyte concentration show a hexagonal wurtzite structure and a strong (002) diffraction peak. With increase of electrolyte concentration, the intensity of diffraction peaks increase and wurtzite ZnO (002) preferred orientation is strengthen, what’more, the average crystalline size of ZnO thin films decrease. The results of SEM show all samples are nanorods, and the inclination and density of nanorods increasing with increasing of electrolyte concentration. The PL show all samples have a narrow UV emission band and a broad emission band in visible region. When electrolyte concentration increase, the peak in UV region decrease, and the peak lecated in visible region increase, too. Raman spectra exhibit three peaks which are located at 439 cm-1,562 cm-1 and 1095 cm-1. The analysis of wettability show that all samples exhibit a light induced transition from hydrophobicity to hydrophilic under UV irradiation. Before UV irradiation, all samples are hydrophobic and the contact angles (CA) of ZnO thin films were all around 108°-118°, after UV irradiation, all samples exhibit hydrophilic. Electrolyte concentration has a obviously influence in wettability. Optical properties show that the band gap of ZnO increased with electrolyte concentration increased, and was approaching standard 3.37 eV. All samples have a obvious photocatalytic degradation on methyl orange, and different sample exhibit different photocatalytic degradation efficiency and photocatalytic degradation rate.Micro structure, surface morphology, optical properties change when electrodeposited time changes. The result of XRD show that all samples is hexagonal wurtzite structure, when electrodeposited time is 30 min,60 min and 120 min, samples exhibited a obvious (002) peak, and with electrodeposited time increased, wurtzite ZnO (002) preferred orientation was strengthen, the average crystalline size of ZnO thin films increased. The SEM images show that the ZnO thin films become more dense when electrodeposited time increase, and morphology analysis changes from nanorods to nanocones, and new nanorods generated at all time. The PL spectra of ZnO thin films exhibit a narrow UV band centering at about 377 nm and broad visible emissions around 600 nm, the peak at UV band centering increase when electrodeposited time increase. Raman spectra of ZnO thin films exhibit three peaks which are located at 439 cm-1,562 cm-1 and 1095 cm-1, but the sample electrodeposited at 10 min haven’t the peak of 439... |
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