Double-shelled Hollow Spheres Research Articles

Trapping of heavy metal ions from electroplating wastewater with phosphorylated double-shelled hollow spheres

The mesoporous multi-shelled hollow structures are promising for trapping of non-degradable heavy metal ions in wastewater but difficult to synthesize. We successfully demonstrated a simple strategy for the construction of mesopore windows on double-shelled α-Fe2O3 hollow spheres. A step-by-step proof of concept synthesis mechanism has been revealed by using mainly electron microscopy and thermogravimetric analysis. We proved that mesopore windows are indispensable to realize the complete surface coverage of phosphonate ligands on α-Fe2O3 double-shelled hollow spheres. The phosphonic groups inherently coordinated with Ni(II) and Cu(II) ions and formed complexes of high stability. Importantly, owing to the structural merits, the phosphorylated double-shelled hollow spheres selectively removes Ni(II) and Cu(II) at wider sample pH range with a high capacity of 380 mg g−1 and 410 mg g−1, respectively. In addition, no significant decrease in the removal efficiency was observed under high salt matrix. For electroplating industry wastewater, the novel structure performs simultaneous Ni(II) and Cu(II) removal, thus producing effluent of stable quality that meets local discharge regulations.

Highly efficient synthesis of CeO2@g-C3N4 double-shelled hollow spheres for ultrasensitive self-enhanced electrochemiluminescence biosensors

In this work, CeO2@g-C3N4 double-shelled hollow spheres were skillfully synthesized as a novel type self-enhanced electrochemiluminescent (ECL) emitter by a highly efficient outside-in hard template method. Thanks to its great catalytic ability, CeO2 were served as a co-reaction accelerator for improving ECL performance of the hollow g-C3N4 spheres (HCNSs)/S2O82− system. In addition, the self-enhanced ECL emitter is designed as a complex containing a co-reaction accelerator and a luminophore to shorten the electron transfer path, which decreases the energy loss of the luminophore significantly. More importantly, the unique double-shelled hollow structure not only greatly decreases the inner filtering effect, but also maximizes the utilization efficiency of the ECL luminophores by increasing a CeO2 shell inside the HCNSs as co-reaction accelerator, effectively enhancing the ECL intensity. Under the optimal conditions, the designed ECL immunosensor showed excellent performance in the determination of CA19-9 with a linear range of 0.50 mU mL−1 –500.00 U mL−1 and a low detection limit of 0.039 mU mL−1. Importantly, the resulting biosensor has good stability, high sensitivity and reliable reproducibility, suggesting its potential application in clinical research.

Engineering tandem double p-n heterostructured CeO2@CdS-Cu8S5 hollow spheres for remarkable photocatalytic CO2 reduction

Carbon cycling and value-added CO2 utilization through photocatalytic CO2 reduction are effective strategies for solving environmental problems and energy crises. Here, we rationally design and fabricate a double p-n heterostructured CeO2@CdS-Cu8S5 double-shelled hollow sphere (DSHSs) photocatalyst, which efficiently and stably performs photocatalytic CO2 reduction under visible light irradiation. Firstly, CeO2 hollow spheres were prepared by the template-assisted method. Then ultrathin CdS nanolayers were grown in situ by the chemical bath deposition method. Finally, part of the CdS was converted to Cu8S5 by cation exchange, resulting in the CeO2@CdS-Cu8S5 hybrid with uniform interfacial contact and ultrathin double-shelled hollow spherical structure. The constructed tandem double p-n heterostructure contributes to the excellent photo-induced charge separation and migration capability of the CeO2@CdS-Cu8S5 photocatalyst. Thanks to the multiple light scattering inside the double-shelled hollow structure, solar radiation can be absorbed more efficiently. In addition, the abundant exposed active sites also significantly contribute to the chemisorption of CO2 molecules and the progress of surface redox reactions. Based on the above properties, the optimized CeO2@CdS-Cu8S5 DSHSs without any noble metal cocatalyst exhibited excellent activity (18.25 µmol g–1h−1) and high selectivity (89.3%) during the photocatalytic reduction of CO2 deoxygenation to CH4.

Multiphase Molybdenum Carbide Doped Carbon Hollow Sphere Engineering: The Superiority of Unique Double-Shell Structure in Microwave Absorption.

In order to achieve excellent electromagnetic wave (EMW) absorption properties, the microstructure design and component control of the absorber are critical. In this study, three different structures made of Mo2 C/C hollow spheres are prepared and their microwave absorption behavior is investigated. The Mo2 C/C double-shell hollow spheres consisting of an outer thin shell and an inner rough thick shell with multiple EMW loss mechanisms exhibit good microwave absorption properties. In order to further improve the microwave absorption properties, MoC1-x /C double-shell hollow spheres with different crystalline phases of molybdenum carbide are prepared to further optimize the EMW loss capability of the materials. Finally, MoC1-x /C double-shell hollow spheres with α-phase molybdenum carbide have the best microwave absorption properties. When the filling is 20 wt.%, the minimum reflection loss at 1.8mm is -50.55dB and the effective absorption bandwidth at 2mm is 5.36GHz, which is expected to be a microwave absorber with the characteristics of "thin, light, wide, and strong".

Scalable Preparation of Sub-Millimeter Double-Shelled Al2O3 Hollow Spheres and Their Rapid Separation from Wastewater after Adsorption of Congo Red.

Porous double-shelled ceramic hollow spheres (PDSs) have attracted extensive attention due to their high specific surface areas and multifunctional designs. When used in wastewater treatment, millimeter or sub-millimeter spheres can be quickly separated from water by commercial sieves. However, the simple, scalable, and low-cost preparation of sub-millimeter PDSs in the solid phase remains a challenge. Herein, porous PDSs were facilely fabricated via a spheronization process utilizing pseudoboehmite powders and wet gelatin spheres as templates, which broke through the difficulty of preparing PDSs by one-step solid-state synthesis. Treating pseudoboehmite powder with nitric acid can improve the compressive strength of the PDSs. By controlling the rolling time and gelatin concentration of gelatin microspheres, the integrity, shell thickness, and double-shelled spacing of the gelatin microspheres were tuned. When the rolling time was 8–12 min, and the gelatin concentration in gelatin spheres was 250 g/L, and PDSs with a complete double-shelled structure, good mechanical property, and high specific surface area (327.5–509.6 m2/g) were obtained at 600 °C. The adsorption capacities of the PDSs for 100 mg/L Congo red solution (70.7 mg/g) were larger than those of single-shelled hollow spheres (49 mg/g), and larger diameters (608–862 μm) of the PDSs allow them to be rapidly separated from solution by a commercial sieve. This paper provides a facile and scalable method for the preparation of sub-millimeter PDSs and demonstrates their excellent adsorption capacity for Congo red solution.

Double-shelled CeO2 coupled CdZnS nanoparticles as an efficient heterojunction visible light photocatalyst for hydrogen evolution

Designing of novel semiconductor photocatalysts toward high-efficient catalytic H2 generation has played a potential role in developing sustainable energy. Here, nanostructured CeO2/CdZnS/ZnO composite material has been synthesized through simple hydrothermal process. The present photocatalyst exhibits high photocatalytic activity for H2 generation under visible light irradiation (λ > 420 nm). It can be possibly explained: First, the ZnO layer formed on double-shelled CeO2 hollow spheres (D-CeO2) by the priority adsorption of Zn2+ exhibits both efficient hole consumption and photo-corrosion inhibition. Second, superior charge separation and charge transfer efficiency originates from the Z-scheme CeO2/CdZnS heterojunction.

BTA loaded in various CeO2 nanocontainers in epoxy coating for long-term anticorrosion of low carbon steel

To figure out the behavior of benzotriazole (BTA) loaded in CeO2 nanocontainers during long term anticorrosion, three kinds of CeO2 spheres were used: hollow spheres (HSs), double-shell hollow spheres (DHSs), and solid-mesoporous spheres (SSs). The BTA loading and releasing situations were checked, and CeO2-HSs exhibited the largest BTA loading amount of 12.5 wt%, forming by both chemical and physical adsorption. The highest BTA loading in CeO2-HSs may be attributed to its hollow structure and more Ce3+ sites (39 %) for BTA anchoring. Thus, CeO2-HSs@BTA exhibited an excellent long-term anticorrosion in epoxy coating for low carbon steel protection, showing no rusting after 40 days of salt spray experiment.

Tandem catalysis with double-shelled hollow spheres.

Metal-zeolite composites with metal (oxide) and acid sites are promising catalysts for integrating multiple reactions in tandem to produce a wide variety of wanted products without separating or purifying the intermediates. However, the conventional design of such materials often leads to uncontrolled and non-ideal spatial distributions of the metal inside/on the zeolites, limiting their catalytic performance. Here we demonstrate a simple strategy for synthesizing double-shelled, contiguous metal oxide@zeolite hollow spheres (denoted as MO@ZEO DSHSs) with controllable structural parameters and chemical compositions. This involves the self-assembly of zeolite nanocrystals onto the surface of metal ion-containing carbon spheres followed by calcination and zeolite growth steps. The step-by-step formation mechanism of the material is revealed using mainly in situ Raman spectroscopy and X-ray diffraction and ex situ electron microscopy. We demonstrate that it is due to this structure that an Fe2O3@H-ZSM-5 DSHSs-showcase catalyst exhibits superior performance compared with various conventionally structured Fe2O3-H-ZSM-5 catalysts in gasoline production by the Fischer-Tropsch synthesis. This work is expected to advance the rational synthesis and research of hierarchically hollow, core-shell, multifunctional catalyst materials.

Nitrogen-doped carbon@TiO2 double-shelled hollow spheres as an electrochemical sensor for simultaneous determination of dopamine and paracetamol in human serum and saliva

As the most commonly used antipyretic and analgesic drug, paracetamol (PA) coexists with neurotransmitter dopamine (DA) in real biological samples. Their simultaneous determination is extremely important for human health, but they also interfere with each other. In order to improve the conductivity, adsorption affinity, sensitivity, and selectivity of TiO2-based electrochemical sensor, N-doped carbon@TiO2 double-shelled hollow sphere (H–C/N@TiO2) is designed and synthesized by simple alcoholic and hydrothermal method, using polystyrene sphere (PS) as a template. Meanwhile, TiO2 hollow spheres (H–TiO2) or N-doped carbon hollow spheres (H–C/N) are also prepared by the same method. H–C/N@TiO2 has good conductivity, charge separation, and the highly enhanced and stable current responses for the detection of PA and DA. The detection limit and linear range are 50.0 nmol/L and 0.3–50 μmol/L for PA, 40.0 nmol/L and 0.3–50 μmol/L for DA, respectively, which are better than those of carbon-based sensors. Moreover, this electrochemical sensor, with high selectivity, strong anti-interference, high reliability, and long time durability, can be used for the simultaneous detection of PA and DA in human blood serum and saliva. The high electrochemical performance of H–C/N@TiO2 is attributed to the multi-functional combination of different layers, because of good conductivity, absorption and electrons transfer ability from in-situ N-doped carbon and electrocatalytic activity from TiO2.

Mo2 C/C Hierarchical Double-Shelled Hollow Spheres as Sulfur Host for Advanced Li-S Batteries.

One of the major challenges regarding the sulfur cathode of Li-S batteries is to achieve high sulfur loading, fast Li ions transfer, and the suppression of lithium polysulfides (LiPSs) shuttling. This issue can be solved by the development of molybdenum carbide decorated N-doped carbon hierarchical double-shelled hollow spheres (Mo2 C/C HDS-HSs). The mesoporous thick inner shell and the central void of the HDS-HSs achieve high sulfur loading, facilitate the ion/electrolyte penetration, and accelerate charge transfer. The microporous thin outer shell suppresses LiPSs shuttling and reduces the charge/mass diffusion distance. The double-shelled hollow structure accommodates the volume expansion during lithiation. Furthermore, Mo2 C/C composition renders the HDS-HSs cathode with improved conductivity, enhanced affinity to LiPSs, and accelerated kinetics of LiPSs conversion. The structural and compositional advantages render the Mo2 C/C/S HDS-HSs electrode with high specific capacity, excellent rate capability, and ultra-long cycling stability in the composed Li-S batteries.

RETRACTED ARTICLE: Synthesis and Application of Double-Shelled CuCo2O4 Hollow Sphere Catalyst for Chemical Fixation of CO2

RETRACTED ARTICLE: Synthesis and Application of Double-Shelled CuCo2O4 Hollow Sphere Catalyst for Chemical Fixation of CO2

A Sandwich-Type Immunosensor Based on Pd NPs@DSHSs-Cu2O and Au NPs Functionalized Graphene Oxide Doped Poly(3,4-ethylenedioxythiophene) Nanorod for Quantitative Detection NSE

Changes in the concentration of neuron-specific enolase (NSE) can be used as an indicator for many diseases. Electrochemical immunosensor is a reliable tool for early diagnosis, but achieving ultrasensitive analysis is a pressing problem. In this work, graphene oxide doped poly (3,4-ethylenedioxythiophene) (PEDOT/GO) spindle-like nanorods prepared by liquid/liquid interface polymerization method have good stability and high conductivity. The sulfur atoms on the thiophene ring combine with gold nanoparticles (Au NPs) to further improve the efficiency of interface electron transfer. Besides, the exposed carboxyl groups and Au NPs on the surface of PEDOT/GO can effectively couple with the capture antibody (Ab1). Double-shelled Cu2O hollow spheres (Pd NPs@DSHSs-Cu2O) modified with palladium nanoparticles (Pd NPs) are used as signal markers. The abundant catalytic active sites and detection antibody (Ab2) binding sites rely on the double-shell hollow spheres to increase the specific surface area. The combined effect of Cu2O and Pd NPs can efficiently catalyze H2O2 to realize the amplification of electrical signals. The detection range of the immunosensor prepared by the above-mentioned sensing strategy was 50.0 fg ml−1 ∼ 100.0 ng ml−1, and the detection limit was 7.54 fg ml−1, which provides potential reference value for early clinical diagnosis.

Bimetal carbonaceous templates for multi-shelled NiCo2O4 hollow sphere with enhanced xylene detection

Abstract Xylene (C8H10) is one of the most hazardous volatile organic compounds, thus highly sensitive gas sensor with real-time monitoring capabilities at lower concentration level is crucial. Hollow and multi-shelled oxide nanostructures are very promising design options for gas sensors due to their low density, high surface area and well-aligned nano-porous structures with less agglomerated configurations. Here, NiCo2O4 double-shelled hollow spheres (DHSs) with porous surfaces are successfully synthesized via a self-templating strategy followed by a simple post-annealing process, in which bimetal self-assembly carbonaceous microspheres (CMS) are employed as a sacrificial template. The crystallinity, morphology, and microstructure of NiCo2O4 DHSs are detailedly characterized. The formation mechanism of double-shelled hollow structure is also discussed. The as-prepared NiCo2O4 DHSs possess large specific surface area as high as ∼93.5 m2 g−1, which not only supply outstanding gas permeability and more reactive sites but also accelerate the diffusion of gas molecules. The sensitivity and response time based on NiCo2O4 DHSs are 23.3 and 15.4 s to 100 ppm xylene at the optimal working temperature (240 °C), respectively.

A high-energy-density supercapacitor with multi-shelled nickel-manganese selenide hollow spheres as cathode and double-shell nickel-iron selenide hollow spheres as anode electrodes.

Thanks to the attractive structural characteristics and unique physicochemical properties, mixed metal selenides (MMSes) can be considered as encouraging electrode materials for energy storage devices. Herein, a straightforward and efficient approach is used to construct multi-shelled nickel-manganese selenide hollow spheres (MSNMSeHSs) as cathode and double-shell nickel-iron selenide hollow spheres (DSNFSeHSs) as anode electrode materials by tuning shell numbers for supercapacitors. The as-designed MSNMSeHS electrode can deliver a splendid capacity of ∼339.2 mA h g-1/1221.1 C g-1, impressive rate performances of 78.8%, and considerable longevity of 95.7%. The considerable performance is also observed for the DSNFSeHS electrode with a capacity of 258.4 mA h g-1/930.25 C g-1, rate performance of 75.5%, and longevity of 90.9%. An efficient asymmetric apparatus (MSNMSeHS||DSNFSeHS) fabricated by these two electrodes depicts the excellent electrochemical features (energy density of ≈112.6 W h kg-1 at 900.8 W kg-1) with desirable longevity of ≈94.4%.

CQDs decorated oxygen vacancy-rich CeO2/BiOCl heterojunctions for promoted visible light photoactivity towards chromium (Ⅵ) reduction and rhodamine B degradation

Engineering a heterojunction with high photoactivity and better exciton separation in photocatalyst is a promising target for environmental purification. In this context, we fabricated CQDs decorated double-shell CeO2 hollow spheres(D-CeO2)/BiOCl heterojunction (D-CeO2: CQDs/BiOCl) composite by a simple method and scrutinized it photocatalytic performance toward chromium (Ⅵ) reduction and rhodamine B degradation. The resultant D-CeO2: CQDs/BiOCl composite is validated much more active under visible light irradiation with the high rhodamine B degradation rate of 0.12min−1 which is about 3 and 255 times, meanwhile, chromium (Ⅵ) reduction rate of 0.015 min−1 which is about 6 and 32 times higher than the neat BiOCl and D-CeO2, respectively. The interfacial domain of D-CeO2/BiOCl decorated with CQDs for efficient photoinduced charge carriers transfer and separation are the point to attractive photocatalytic performance which combines the double-shell hollow sphere morphology with highly efficient light harvesting, rich OVs for the charge carriers fast separation and accelerated charge transfer after the CQDs participating.

Enhanced ammonia detection using wrinkled porous CoFe2O4 double-shelled spheres prepared by a thermally driven contraction process

Hierarchical CoFe2O4 double-shelled hollow spheres (DHSs) with wrinkled porous surfaces are successfully synthesized via a self-templating strategy followed by a simple post-annealing process. The crystallinity, morphology, and microstructure of CoFe2O4 DHSs are detailedly characterized. The as-prepared CoFe2O4 DHSs are composed of homogeneous primary nanoparticles with uniform size and morphology that are hierarchically assembled into well-defined double-shelled spheres with high porosity. The formation mechanism of double-shelled hollow structure is also discussed. Because of their large specific surface area and easily penetrable hierarchical shells, the as-synthesized CoFe2O4 DHSs exhibit high sensitivity to ammonia and fast response-recovery capability at the optimal working temperature.

Ag/Ag2O confined visible-light driven catalyst for highly efficient selective hydrogenation of nitroarenes in pure water medium at room temperature

Although photocatalysis has attracted tremendous research interest, there still remains critical challenges (e.g., low visible-light quantum efficiency, organic media, etc.), especially for selective hydrogenation of nitroarenes. Herein, we design and synthesize the first confined photocatalyst by introducing the nanospace of double-shelled hollow silica sphere as a photocatalytic nanoreactor to promote the hydrogenation reaction with the fast reaction kinetics. This photocatalyst exhibits excellent activity, selectivity, and recyclability. Especially, superior selectivity (>99%) is achieved when used for the hydrogenation of nitroarenes under visible-light irradiation in pure water medium. Both experimental and theoretical simulation results indicate that the Ag/Ag2O structure and confined nanospace of the photocatalyst greatly increase the contact probability between photogenerated atomic hydrogen and nitroarenes. Additionally, corresponding anilines are obtained almost quantitatively towards the hydrogenation of nitroarenes in pure water medium at room temperature. Therefore, this work provides a rational design concept of highly efficient visible-light photocatalyst for green chemistry industry.

Correction: Y2O3:Yb,Er@mSiO2-CuxS double-shelled hollow spheres for enhanced chemo-/photothermal anti-cancer therapy and dual-modal imaging.

Correction for 'Y2O3:Yb,Er@mSiO2-CuxS double-shelled hollow spheres for enhanced chemo-/photothermal anti-cancer therapy and dual-modal imaging' by Dan Yang et al., Nanoscale, 2015, 7, 12180-12191, DOI: 10.1039/C5NR02269J.

MOF assistance synthesis of nanoporous double-shelled CuCo2O4 hollow spheres for hybrid supercapacitors

Design of complex hollow nanostructures of two or more transition metal oxides seems to be necessary to answer the demand for novel energy storage electrodes owning outstanding performance for advanced developments of modern electronics. Herein, we develop a metal-organic frameworks (MOFs) assistance self-templated method for the synthesis of double-shell CuCo2O4 hollow spheres as battery-type electrode material with a large surface area of 93 m2 g−1. This electrode material reveals excellent electrochemical performance with an ultrahigh specific capacity of 701 C g−1 at 2 A g−1. Additionally, remarkably high cycling performance is exhibited with maintaining more than 93.6% of the initial capacity after 6000 cycles. The assembly of the double-shell hollow spheres electrode with reduced graphene oxide (rGO) electrode in an asymmetric cell results in a high-performance supercapacitor with an energy density of 38.4 Wh kg−1 and a power density of 16 kW kg−1, that is remarkably higher than that of conventional supercapacitors and comparable with Ni-MH batteries. Additionally, we display that assembling two asymmetric devices in series could effectively power blue, green, and red LED indicators. The excellent electrochemical performance of the ZCCO electrode shows its high potential for the production of advanced energy storage devices.

Double-shelled hollow carbon spheres confining tin as high-performance electrodes for lithium ion batteries

Alloy-type materials hold a great potential as the negative electrodes for next generation lithium-ion batteries with high energy and low cost. However, the huge volume expansion of alloy-type materials caused by lithium alloying inevitably leads to poor cycle stability. Herein, we propose a rational design of a sandwich structure of carbon/Sn/carbon hollow spheres by a template-engaged method. The structure effect of the novel carbon/Sn/carbon spheres on the lithium storage performances is elucidated by various means of characterization and electrochemical tests. A stable and high reversible capacity of 1100 mA h g−1 is retained after 130 cycles at 0.1 A g−1, significantly higher than that (187 mA h g−1) of Sn/carbon hollow spheres. Furthermore, a superior rate capability is obtained for carbon/Sn/carbon spheres, e.g., showing a high capacity of 430 mA h g−1 at 5 A g−1. The excellent electrochemical properties of carbon/Sn/carbon against Sn/carbon are ascribed to a unique nano-confinement from the double-shelled carbons with very good structure stability and contribution of pseudocapacitive storage of lithium. These results indicate that the sandwich structure of carbon/Sn/carbon is highly effective to design electrode materials with enhanced performances.