Choudhary Siddharth, Kumar Vishnu, Malik Vidhu, Nagarajan Rajamani, Annapoorni S, Malik Rakesh
Department of Physics and Astrophysics, University of Delhi, Delhi-110007, India.
Department of Chemistry, University of Delhi, Delhi-110007, India.
J Phys Condens Matter. 2020 Jul 8;32(40). doi: 10.1088/1361-648X/ab9e2e.
The photocatalytic activity (PCA) of ZnO@Ag nanocomposites for different concentrations of Ag is reported. Dumbbells shaped zinc oxide (ZnO) nanostructures with silver (Ag) nanoparticles were synthesized by a simple chemical colloidal method. The as synthesized nanocomposites (without any heat treatment) were used for optical and photocatalytic studies. The FESEM analysis shows that the composite catalysts are composed of ZnO dumbbells coated with spherical Ag nanoparticles. UV-visible spectrum of ZnO@Ag photocatalysts shows a strong absorption band of ZnO at 380 nm with a plasmonic peak of Ag at 440 nm. The PL emission intensity of the composites varies with Ag concentration and has a minimum for the catalyst containing 13.7% of Ag. A possible growth mechanism of ZnO nanostructures with hexagonal cross-section has been proposed. Photocatalytic property of the as synthesized ZnO and ZnO@Ag catalysts was studied by investigating the degradation of methylene blue (MB) dye on exposure to UV-visible radiation. A relatively faster degradation of the dye was observed for ZnO@Ag composites as compared to pure ZnO, showing an improved photocatalytic behavior in the visible region. We proposed a possible mechanism for the enhancement in photocatalytic activity of Ag coated ZnO photocatalysts.
报道了不同银浓度的ZnO@Ag纳米复合材料的光催化活性（PCA）。采用简单的化学胶体法合成了带有银（Ag）纳米颗粒的哑铃状氧化锌（ZnO）纳米结构。合成后的纳米复合材料（未经任何热处理）用于光学和光催化研究。场发射扫描电子显微镜（FESEM）分析表明，复合催化剂由包覆有球形Ag纳米颗粒的ZnO哑铃组成。ZnO@Ag光催化剂的紫外可见光谱显示，在380 nm处有一个强的ZnO吸收带，在440 nm处有一个Ag的等离子体峰。复合材料的光致发光（PL）发射强度随Ag浓度而变化，对于含13.7%Ag的催化剂，其PL发射强度最小。提出了具有六边形横截面的ZnO纳米结构的一种可能生长机制。通过研究亚甲基蓝（MB）染料在紫外可见辐射下的降解情况，研究了合成后的ZnO和ZnO@Ag催化剂的光催化性能。与纯ZnO相比，ZnO@Ag复合材料对染料的降解相对较快，在可见光区域表现出改善的光催化性能。我们提出了一种提高Ag包覆ZnO光催化剂光催化活性的可能机制。
