Hendrix Yuri, Rauwel Erwan, Nagpal Keshav, Haddad Ryma, Estephan Elias, Boissière Cédric, Rauwel Protima
Institute of Forestry and Engineering Sciences, Estonian University of Life Sciences, 51014 Tartu, Estonia.
Institute of Veterinary Medicine and Animal Sciences, Estonian University of Life Sciences, 51006 Tartu, Estonia.
Nanomaterials (Basel). 2023 Jul 3;13(13):1998. doi: 10.3390/nano13131998.
ZnO is an effective photocatalyst applied to the degradation of organic dyes in aqueous media. In this study, the UV-light and sunlight-driven photocatalytic activities of ZnO nanoparticles are evaluated. A handheld Lovibond photometer was purposefully calibrated in order to monitor the dye removal in outdoor conditions. The effect of ZnO defect states, i.e., the presence of zinc and oxygen defects on the photocatalytic activity was probed for two types of dyes: fuchsin and methylene blue. Three morphologies of ZnO nanoparticles were deliberately selected, i.e., spherical, facetted and a mix of spherical and facetted, ascertained via transmission electron microscopy. Aqueous and non-aqueous sol-gel routes were applied to their synthesis in order to tailor their size, morphology and defect states. Raman spectroscopy demonstrated that the spherical nanoparticles contained a high amount of oxygen vacancies and zinc interstitials. Photoluminescence spectroscopy revealed that the facetted nanoparticles harbored zinc vacancies in addition to oxygen vacancies. A mechanism for dye degradation based on the possible surface defects in facetted nanoparticles is proposed in this work. The reusability of these nanoparticles for five cycles of dye degradation was also analyzed. More specifically, facetted ZnO nanoparticles tend to exhibit higher efficiencies and reusability than spherical nanoparticles.
氧化锌是一种应用于水介质中有机染料降解的有效光催化剂。在本研究中，评估了氧化锌纳米颗粒在紫外光和太阳光驱动下的光催化活性。为了监测户外条件下的染料去除情况，特意校准了手持式罗维朋光度计。针对两种染料：品红和亚甲基蓝，探究了氧化锌缺陷态，即锌和氧缺陷的存在对光催化活性的影响。通过透射电子显微镜特意选择了三种氧化锌纳米颗粒形态，即球形、多面体以及球形和多面体的混合形态。采用水相和非水相溶胶 - 凝胶法合成这些纳米颗粒，以调整其尺寸、形态和缺陷态。拉曼光谱表明，球形纳米颗粒含有大量氧空位和锌间隙原子。光致发光光谱显示，多面体纳米颗粒除了含有氧空位外，还存在锌空位。本工作提出了一种基于多面体纳米颗粒中可能存在的表面缺陷的染料降解机制。还分析了这些纳米颗粒在五个染料降解循环中的可重复使用性。更具体地说，多面体氧化锌纳米颗粒往往比球形纳米颗粒表现出更高的效率和可重复使用性。
