Enhanced optical properties of heterostructured ZnO/CeO_2 nanocomposite fabricated by one-pot hydrothermal method: Fluorescence and ultraviolet absorption and visible light transparency

摘要

Many researchers investigated the properties of either discrete metal oxide CeO_2 or ZnO materials. However, less attention has been paid to the various nanostructure and performances of CeO_2 and ZnO nanocomposite up to now. In this paper, a facile and low cost one-pot hydrothermal synthesis method has been adopted to obtained directly precursors of CeCO_3OH and Zn_5(CO_3)_2(OH)_6 with different Ce atom molar ratios to Zn, which are transformed into their corresponding metal oxide to form the ZnO/CeO_2 heterostructure nanocomposites (HSNCs) by pyrolysis. The heterostructure is composed of ZnO and CeO_2 monocrystals, simultaneously, CeO_2 monocrystals are well dispersed on the surface of ZnO monocrystal for cosmetics. Bing dependent on the analysis results of XRD and TEM for the obtained precursors before and after pyrolysis, the formation mechanism of HSNCs was proposed. To the best of our knowledge, the paper first reported heterostructured ZnO/CeO_2 nanocomposite grown in one-pot mixed aqueous solution of cerium nitrate, zinc acetate and urea without other extra surfactant. Additionally, the influence of various Ce/Zn molar ratios on the heterostructure, fluorescence emission and UV-visible absorption properties of HSNCs was investigated in detail. ZnO/CeO_2 HSNCs display higher fluorescence emission with the increasing Ce/Zn molar ratio. Meanwhile, the larger Ce/Zn molar ratio of ZnO/CeO_2 HSNCs, the stronger transparency in the visible light region and the weaker UV absorption. The results are due to the fact that the band gap of ZnO/CeO_2 HSNCs will decrease from 3.25 to 3.08 eV when Ce/Zn atom molar ratio is increased from 0 to 0.08. By the comprehensive analysis on the optical performances of HSNCs with the different Ce/Zn atom molar ratios, ZnO/CeO_2-0.04 HSNCs could become UV absorber materials and transparent material in the visible region. ZnO/CeO_2-0.04 HSNCs with the UV-filtering and Vis-transparent properties is appropriate for personal-care cosmetics.