Aqueous Synthesis of Water-Soluble L-Cysteine-Modified Cadmium Sulfide Doped with Silver Ion/Zinc Sulfide Nanocrystals

The water-soluble silver ion-doped cadmium sulfide nanocrystals were synthesized by a co-precipitation technique in aqueous solution using L-cysteine as surface modifier, and then L-cysteine-modified cadmium sulfide doped with silver ion/zinc sulfide core/shell nanocrystals were prepared by zinc sulfide epitaxial coated on surface of silver ion-doped cadmium sulfide nanocrystals. The crystal structure, morphology, and spectral properties of cadmium sulfide doped with silver ion/zinc sulfide nanocrystals were characterized by X-ray power diffraction, transmission electron microscope, infrared spectrum, and photoluminescence spectrum. The results show that the photoluminescence quantum yield of cadmium sulfide doped with silver ion/zinc sulfide nanocrystals is improved greatly after doped with silver ion and coated with zinc sulfide shell. The cysteine modified on the surface of cadmium sulfide doped with silver ion/zinc sulfide nanocrystals renders the nanocrystals water-soluble and biocompatible.     

Component‐Controlled Synthesis of Small‐Sized Pd‐Ag Bimetallic Alloy Nanocrystals and Their Application in a Non‐Enzymatic Glucose Biosensor

Small‐sized monodisperse Pd‐Ag alloy nanocrystals (NCs) are synthesized via a solid‐liquid and solid‐solid phase chemical route, i.e., sequential reduction of Pd(NO₃)₂ and AgNO₃ solid precursors in the liquid mixture of dodecylamine and 1‐octadecene, followed by fusion of formed Pd and Ag NCs at 250 °C. By controlling the addition sequence and molar ratio of the metallic precursors, a series of Pd‐Ag alloy NCs, including Pd₅Ag, Pd₂Ag, PdAg, PdAg₂, and PdAg₅, is obtained. The alloy NCs are highly crystallized and exhibit a strong atomic ensemble in addition to component‐dependent electronic effects. Pd₂Ag NCs have unique structure and electronic properties, showing a much faster electron transfer process at a modified glassy carbon electrode interface compared with that of other alloys. Therefore, the Pd₂Ag NCs are chosen as the electrocatalyst to evaluate the performance of Pd‐Ag nanoalloy and a novel non‐enzymatic glucose biosensor is fabricated. The biosensor exhibits an acceptable reproducibility, a good stability and low interferences, which can be used to examine glucose in clinic blood serum samples. This work provides a simple multiphasic reaction system to synthesize binary alloy NCs with well‐controlled componential ratio and opens the avenue to utilize them in biosensing or other advanced technological fields.     

KY3F10:Yb3+,Tm3+,Ho3+纳米晶在单一980 nm辐射下的色稳定上转换白光

利用简单的水热法制备了立方相KY₃F₁₀∶15% Yb³⁺,0.5% Tm³⁺,0.2% Ho³⁺上转换纳米晶。在980 nm激发下,获得接近等能白的上转换发光。上转换机理分析表明,蓝、绿、红光发射分别源自Yb³⁺到Tm³⁺和Ho³⁺的能量传递。更重要的是,该上转换白光显示了良好的色稳定性。当泵浦功率由688 mW增加到1 688 mW,色差仅为0.027 5。其原因在于,一方面三基色发光的功率关系比较接近;另一方面蓝光的功率关系随泵浦功率的增加逐渐减小,而绿、红光的功率关系保持不变。蓝光的饱和现象可能与激光辐射所引起的热效应有关。