Facile Size Control Research Articles

Directional Modulation of Exciton Emission Using Single Dielectric Nanospheres.

Coupling emitters with nanoresonators is an effective strategy to control light emission at the subwavelength scale with high efficiency. Low-loss dielectric nanoantennas hold particular promise for this purpose, owing to their strong Mie resonances. Herein, a highly miniaturized platform is explored for the control of emission based on individual subwavelength Si nanospheres (SiNSs) to modulate the directional excitation and exciton emission of 2D transition metal dichalcogenides (2D TMDs). A modified Mie theory for dipole-sphere hybrid systems is derived to instruct the optimal design for desirable modulation performance. Controllable forward-to-backward intensity ratios are experimentally validated in 532nm laser excitation and 635nm exciton emission from a monolayer WS2 . Versatile light emission control is achieved for different emitters and excitation wavelengths, benefiting from the facile size control and isotropic shape of SiNSs. Simultaneous modulation of excitation and emission via a single SiNS at visible wavelengths significantly improves the efficiency and directionality of TMD exciton emission and leads to the potential of multifunctional integrated photonics. Overall, the work opens promising opportunities for nanophotonics and polaritonic systems, enabling efficient manipulation, enhancement, and reconfigurability of light-matter interactions.

Synthesis and facile size control of well-dispersed cobalt nanoparticles supported on ordered mesoporous carbon

Ordered mesoporous carbons, as potential catalyst supports, have attracted great attention in the catalysis field in recent years. Researchers have attempted to introduce guest particles into these carbons by versatile methods. Great success has been achieved with noble metal particles because of their lower sintering tendency. However, challenges occurred with more active metals such as cobalt because of their much higher sintering tendency, the hydrophobic nature of the carbon surface and channel confinement effects, which were believed to have prevented the wetness of the surface. Most researchers found that the carbon surface had to be specially treated to achieve good metal dispersion. In our current work, cobalt@carbon composites were synthesized using CMK-3 as the carbon support and cobalt nitrate hexahydrate as the metal precursor. We demonstrated the facile control of the metal particle size and dispersion by carefully controlling the impregnation conditions according to the physical chemistry of the precursor. Our results suggested that not only the acid pre-treatment of the carbon surface and the ammonia post-treatment of the cobalt nitrate precursor improved the metal dispersion but also simple impregnation itself could achieve good metal dispersion if the preparation conditions were controlled as suggested. Highly thermal stable cobalt@carbon composites with very well-controlled cobalt dispersion (15 wt%) and particle size (∼4–20 nm) were produced.

Magnetic nanocomposite multilayers using layer-by-layer assembly in nonpolar and polar solvent

Magnetic nanoparticles have recently attracted a great deal of attentions due to a number of potential applications such as MRI contrast agents, magnetic separation, nonvolatile memory devices or magnetic cards as well as a fundamental scientific interest. The effective use of magnetic nanoparticles in a given application is based on two important factors: the inherent properties of nanoparticles (magnetization, size, etc.) and the ability to tailor their adsorbed amount onto the substrates. It has been reported by several research groups that high temperature decomposition of iron precursors in the presence of capping ligands can induce the high quality particles with facile size control, size uniformity and crystalline in comparison with more traditional coprecipitation/dextran methods or the reduction method in aqueous solution. These nanoparticles obtained from thermal decomposition can be well dispersed in nonpolar solvent due to hydrophobic property of the used stabilizers. Additionally, the particles with negatively charged stabilizers can allow the multiple depositions (i.e., layerby-layer assembled deposition) between particles and oppositely charged components and resultantly can enhance the intensity of their inherent properties such as magnetization. However, to the best of our knowledge, the facile and efficient method fully satisfying these two factors has not been introduced up to date. Herein, we introduce the novel and simple method for the fabrication of magnetic nanocomposite multilayers, including the high quality γ-Fe2O3 nanoparticles (MP) by thermal decomposition method and allowing the tailored magnetic properties. 2-bromo-2-methylpropionic acid (BMPA)-stabilized MP in toluene solvent was prepared by exchanging oleic acid with BMPA after initially synthesizing the oleic acid-stabilized MP (OA-MP). The bromo (-Br) groups of BMPA-MP can be covalently bonded with amine (-NH2) groups. Based on this high affinity, it is demonstrated that the magnetic nanocomposite multilayers can be fabricated using BMPA-MP dispersed in toluene and poly(allyamine hydrochloride) (PAH) in water.

Facile Size-control and Fabrication of Spherical Morphology Based on Amphiphilic Ionic Platinum(II) Complexes

Facile Size-control and Fabrication of Spherical Morphology Based on Amphiphilic Ionic Platinum(II) Complexes

A Facile Size-control Method of CdS Nanoparticles In-situ Synthesized in Polymer Matrix by Adjusting Ratio of Acidic Acid with Metallic Complex in Acrylate Photoresist Resin

Abstract A facile method with efficient control of nanoparticles size in polymer matrix by combination of in situ synthesis and photopolymerization is proposed and investigated. The photoluminescence of the CdS–polymer nanocomposites was easily tuned by adjusting the molar ratio of acrylic acid to cadmium acrylate in designed photoresist resins.