Double-shelled Hollow Nanospheres Research Articles

Synthesis of Double-Shelled Hollow Inorganic Nanospheres through Block Copolymer-Metal Coordination and Atomic Layer Deposition.

Double-shelled hollow (DSH) structures with varied inorganic compositions are confirmed to have improved performances in diverse applications, especially in lithium ion battery. However, it is still of great challenge to obtain these complex nanostructures with traditional hard templates and solution-based route. Here we report an innovative pathway for the preparation of the DSH nanospheres based on block copolymer self-assembly, metal–ligand coordination and atomic layer deposition. Polymeric composite micelles derived from amphiphilic block copolymers and ferric ions were prepared with heating-enabled micellization and metal–ligand coordination. The DSH nanospheres with Fe2O3 stands inner and TiO2 outer the structures can be obtained with atomic layer deposition of a thin layer of TiO2 followed with calcination in air. The coordination was carried out at room temperature and the deposition was performed at the low temperature of 80 °C, thus providing a feasible fabrication strategy for DSH structures without destruction of the templates. The cavity and the outer layer of the structures can also be simply tuned with the utilized block copolymers and the deposition cycles. These DSH inorganic nanospheres are expected to find vital applications in battery, catalysis, sensing and drug delivery, etc.

Nickel Cobalt Sulfide Double-Shelled Hollow Nanospheres as Superior Bifunctional Electrocatalysts for Photovoltaics and Alkaline Hydrogen Evolution.

Transition metal chalcogenides with hollow nanostructures have been considered as promising substitutes as precious metal electrocatalysts for energy conversion and storage. We synthesized NiCo2S4 double-shelled ball-in-ball hollow spheres (BHSs) via a simple solvothermal route and applied them in both dye-sensitized solar cells (DSSCs) and hydrogen evolution reactions (HERs) at the same time, which were clean and sustainable ways to convert energy. Benefiting from their remarkable structure features and advantageous chemical compositions, NiCo2S4 BHSs composed of tiny crystals possessed large surface area, well-defined interior voids, and high catalytic activity. The DSSC with NiCo2S4 BHSs under 100 mW cm-2 irradiation possessed a power conversion efficiency of 9.49% (Pt, 8.30%). Besides, NiCo2S4 BHSs as a HER catalyst also possessed a small onset overpotential (27.9 mV) and a low overpotential (89.7 mV at 10 mA cm-2) under alkaline conditions. Therefore, this work offers a sensible strategy to synthesize bifunctional electrocatalysts for DSSCs and HERs.

Magnetically recyclable nanocatalyst with synergetic catalytic effect and its application for 4-nitrophenol reduction and Suzuki coupling reactions

Magnetically recyclable catalysts with high activity are highly desired in heterogeneous catalysis, as their magnetic nature allows the facile and efficient separation under an external magnetic field. We developed a facile method to fabricate a new type of recyclable nanocatalyst based on double-shelled hollow nanospheres (HNSs) supported Pd nanoparticles (NPs), in which magnetic Fe species were served as inner shell and nitrogen doped carbon (NC) as outer shell. The resultant Fe@NC@Pd HNSs possess unique hollow structure and mesoporous shells for facile mass transportation, magnetic inner shell for easy recycling and well dispersed Pd NPs for high-density of catalytic sites. The magnetic Fe-based inner shell, catalytically active outer NC shell combined with ultrafine Pd NPs synergistically enhanced the catalytic activity and recyclability in organocatalysis. In 4-nitrophenol reduction reaction, the turnover frequency (TOF) of Fe@NC@Pd catalyst is up to 370.3 min−1, which is one of the highest efficiencies ever reported. Furthermore, Fe@NC@Pd can also be applied for Suzuki coupling reaction with the TOF as high as 52.7 min−1.

Precursor-mediated synthesis of double-shelled V2O5hollow nanospheres as cathode material for lithium-ion batteries

Hollow micro-/nanostructures have a wide range of applications in catalysis, rechargeable batteries, drug delivery, and gas sensors, as well as energy storage and conversion. Herein, we report a facile, template-free, precursor-mediated method to synthesize V2O5 nanomaterials with three different architectures: double-shelled hollow nanospheres, single-shelled hollow nanospheres and nanoparticles. These V2O5 nanostructures are obtained via a simple thermal treatment in air of a “pre-synthesized” vanadyl glycerolate precursor, and their morphologies can be easily tuned by varying the thermal treatment temperatures. Electrochemical studies show that the double-shelled V2O5 hollow nanospheres as a cathode material for lithium-ion batteries deliver an initial capacity of 256.7 mA h g−1 with a Coulombic efficiency of nearly 100%, and their capacity is superior to the two other V2O5 nanostructures (i.e., single-shelled hollow nanospheres and nanoparticles), mainly due to their unique double-shelled hollow structure.

Fabrication of mechanically robust, self-cleaning and optically high-performance hybrid thin films by SiO2&TiO2double-shelled hollow nanospheres

Low-cost antireflection (AR) thin films on large-area optical surfaces are important for high-performance optical devices, display devices and photovoltaic cells. In the current work, SiO2&TiO2 double-shell hollow nanospheres (DSHNs) were designed, synthesized and utilized as building blocks for fabricating multifunctional AR thin films. By optimizing the porosity of SiO2&TiO2 DSHN and thin film structure, substrates with DSHN thin films attained transmittance as high as 99.4% and average transmittance up to 98.5% in the visible region. The nano-composite SiO2-TiO2 films exhibited intrinsic superhydrophilicity, anti-fogging and high photocatalytic activity. Tape peeling test, sponge washing test, and high temperature and moisture proof test showed favorable robustness and functional durability of the thin films, which make them extremely attractive for applications in lenses, photovoltaic cells and windows of high-rise buildings.

Polypyrrole single and double-shelled nanospheres templated by pyrrole–Hg(II) complex: Synthesis, characterization, formation mechanism and electrochemical performance

Spherical and yolk/shell nanostructures of pyrrole (Py)–Hg(II) complex have been formed by mixing Py monomer with HgCl2 in aqueous solution as white precipitation. Templated by spherical and yolk/shell nanostructures of Py–Hg(II) complex, polypyrrole (PPy) single and double-shelled hollow nanospheres have been successfully fabricated by simply introducing an oxidant to initial the polymerization of Py monomer on the surface of templates. Formation mechanisms of PPy nanostructures involved have been discussed in detail according to experimental observations. When hollow PPy spheres were used as the electrode materials for the supercapacitors, the specific capacity can achieve 252Fg−1 at the current density of 0.5Ag−1. Results indicated that the material has good cyclic stability, and is suitable to be applied as a good supercapacitor material.

Fabrication of SiO2/TiO2 double-shelled hollow nanospheres with controllable size via sol-gel reaction and sonication-mediated etching.

Size-controllable double-shell SiO2/TiO2 hollow nanoparticles (DS HNPs) were fabricated using a simple sol-gel reaction and sonication-mediated etching. The size of the DS HNPs was controlled using SiO2 core templates of various sizes. Moreover, monodisperse DS HNPs were produced on a large scale (10 g per 1 batch) using the sol-gel method. The surface area and porosity of intrashell and inner-cavity pores were measured by Brunauer-Emmett-Teller analysis. As a result, 240 nm DS HNPs (240 DS HNPs) exhibited the highest surface area of 497 m(2) g(-1) and a high porosity. Additionally, DS HNPs showed excellent light-scattering ability as a scattering layer in dye-sensitized solar cells due to their structural properties, such as a composite, double-shell, hollow structure, as well as intrashell and inner cavity pores. The DSSCs incorporating 240 DS HNPs demonstrated an 18.3% enhanced power conversion efficiency (PCE) compared to TiO2 nanoparticles.

Shape Evolution of New-Phased Lepidocrocite VOOH from Single-Shelled to Double-Shelled Hollow Nanospheres on the Basis of Programmed Reaction-Temperature Strategy

Solid templates have been long regarded as one of the most promising ways to achieve single-shelled hollow nanostructures; however, few effective methods for the construction of multishelled hollow objects from their solid template counterparts have been developed. We report here, for the first time, a novel and convenient route to synthesizing double-shelled hollow spheres from the solid templates via programming the reaction-temperature procedures. The programmed temperature strategy developed in this work then provides an essential and general access to multishelled hollow nanostructures based on the designed extension of single-shelled hollow objects, independent of their outside contours, such as tubes, hollow spheres, and cubes. Starting from the V(OH)(2)NH(2) solid templates, we show that the relationship between the hollowing rate and the reaction temperature obey the Van't Hoff rule and Arrhenius activation-energy equation, revealing that it is the chemical reaction rather than the diffusion process that guided the whole hollowing process, despite the fact that the coupled reaction/diffusion process is involved in the hollowing process. Using the double-shelled hollow spheres as the PCM (CaCl(2).6H(2)O) matrix grants much better thermal-storage stability than that for the nanoparticles counterpart, revealing that the designed nanostructures can give rise to significant improvements for the energy-saving performance in future "smart house" systems.