Hypersonic vibrations of Ag@SiO2 (cubic core)-shell nanospheres

Novel mesoporous Ag@SiO2 nanospheres as a heterogeneous catalyst with superior catalytic performance for hydrogenation of aromatic nitro compounds

Mesoporous core–shell structure Ag@SiO₂ nanospheres are constructed to prevent Ag nanoparticles from aggregation during the hydrogenation reaction. The prepared catalyst shows superior catalytic performance for hydrogenation of nitro compounds with 100% conversion and selectivity without any by-products, which also indicates good recycling performance for several times use.

Mesoporous core–shell structure Ag@SiO₂ nanospheres are constructed to prevent Ag nanoparticles from aggregation during the hydrogenation reaction.

High-performance solution-processed white organic light-emitting diodes based on silica-coated silver nanocubes

Solution-processed white organic light-emitting diodes (WOLEDs) with silica-coated silver nanocubes (Ag@SiO₂ NCs) incorporated at the interface of a hole transporting layer and emission layer are studied. The concentration of Ag@SiO₂ NCs is varied to investigate the effect of Ag@SiO₂ NCs on the performances of WOLEDs. Owing to the sharp edges and corners, Ag NCs greatly improve the radiative rate and emission intensity of nearby blue excitons. The blue emission at different Ag@SiO₂ NC concentrations determines the performance of the WOLEDs. The emission of the orange excitons is strengthened by the high concentration of Ag@SiO₂ NCs, which slightly influences the device performance. On the other hand, the SiO₂ shell and some SiO₂ nanospheres coexisting with Ag NCs reduce the hole transporting, improving the carrier balance in the WOLEDs. The experimental and simulated results also show that excessive Ag@SiO₂ NCs may cause a rough film surface, unbalanced carrier injection, and fluorescence quenching, which decreases the device performance. The optimized WOLED with a proper concentration of Ag@SiO₂ NCs has a peak current efficiency of 53.9 cd/A, acquiring a significant enhancement factor of 77.3% compared to the control device without Ag@SiO₂ NCs.

Superficial-Layer-Enhanced Raman Scattering (SLERS) for Depth Detection of Noncontact Molecules

Although the strength of Raman signals can be increased by many orders of magnitude on noble metal nanoparticles, this enhancement is confined to an extremely short distance from the Raman-active surface. The key to the development of Raman spectroscopy for applications in diagnosis and detection of cancer and inflammatory diseases, and in pharmacology, relies on the capability of detecting analytes that are noninteractive with Raman-active surfaces. Here, a new Raman enhancement system is constructed, superficial-layer-enhanced Raman scattering (SLERS), by covering elongated tetrahexahedral gold nanoparticle arrays with a superficial perovskite (CH₃ NH₃ PbBr₃ ) film. Plasmonic decay is depressed along the vertical direction away from the noble metal surface and the penetration depth is increased in the perovskite media. The vertical penetration of SLERS is verified by the spatial distribution of the analytes via Raman imaging in layer-scanning mode.

Structural Evolution of Co-Based Metal Organic Frameworks in Pyrolysis for Synthesis of Core-Shells on Nanosheets: Co@CoOx@Carbon-rGO Composites for Enhanced Hydrogen Generation Activity

In this article, Co-based metal organic frameworks (MOFs) with two shapes were used as pyrolysis precursor to synthesize multilayer core-shells composites loaded on reduced graphene oxide (rGO) sheets. The core-shell structures were obtained by the formation of cores from metal ions and carbon shells from carbonization of ligands. Controllable oxidation of Co cores to CoOx shells generated multilayer core-shell structures anchored onto the surface of rGO sheets. The N-doped composites were obtained by adding poly vinylpyrrolidone. The multilayer core-shells composites exhibited superior catalytic activity toward hydrogen generation compared to their single layer counterparts. By using the N-doped multilayer composites, high hydrogen generation specific rate of 5560 mL min(-1) gCo(-1) was achieved at room temperature. The rGO sheets in composites improved their structure stability. These catalysts exhibited high stability after used five cycling. This synergistic strategy proposes simple, efficient, and versatile blue-prints for the fabrication of rGO composites from MOFs-based precursors.

Fluorescent Au@Ag core-shell nanoparticles with controlled shell thickness and Hg(II) sensing

Au-Ag core-shell nanoparticles have been synthesized using synthetic fluorescent dipeptide β-Ala-Trp (β-Ala is β-alanine; Trp is l-tryptophan) in water at pH 6.94 and at room temperature. The synthesis of the Au-Ag core-shell nanomaterial does not involve any external reducing and stabilizing agents, and the constituents of dipeptide β-alanine and l-tryptophan are naturally occurring. Therefore, the synthesis procedure is ecofriendly. Moreover, the shell thickness has also been controlled, and the optical property of the core-shell nanomaterial varies with the shell thickness. The core-shell nanomaterial exhibits a fascinating fluorescence property. This fluorescent Au@Ag core-shell nanoparticle can detect toxic Hg(II) ions ultrasensitively (with a lower limit of detection of 9 nM) even in presence of Zn(II), Cd(II), and other bivalent metal ions (Ca(II), Mg(II), Ni(II), Mn(II), Ba(II), Sr(II), Pb(II), and Fe(II)). Au-Ag core-shell nanomaterials can also be reused for sensing Hg(II) ions.