Composite Hollow Microspheres Research Articles

Preparation of RDX/F2311/Fe2O3/Al Composite Hollow Microspheres by Electrospray and Synergistic Energy Release during Combustion between Components.

Nanothermites and high-energy explosives have significantly improved the performance of high-energy composites and have broad application prospects. Therefore, in this study, RDX/F2311/Fe2O3/Al composite hollow microspheres were successfully prepared utilizing the electrospray method using F2311 as a binder between components. The results show that the combustion time of the composite hollow microspheres is shortened from 2400 ms to 950 ms, the combustion process is more stable, and the energy release is more concentrated. The H50 of the composite hollow microspheres increased from 14.49 cm to 24.57 cm, the explosion percentage decreased from 84% to 72%, and the sensitivity of the composite samples decreased significantly. This is mainly the result of the combination of homogeneous composition and synergistic reactions. The combustion results show that F2311 as a binder affects the tightness of the contact between the components. By adjusting its content, the combustion time and the intensity of the combustion of the composite microspheres can be adjusted, which provides a feasible direction for its practical application.

MOF-Derived Urchin-like Co9S8-Ni3S2 Composites on Ni Foam as Efficient Self-Supported Electrocatalysts for Oxygen Evolution Reaction

Effective and inexpensive electrocatalysts are significant to improve the performance of oxygen evolution reaction. Facing the bottleneck of slow kinetics of oxygen evolution reaction, it is highly desirable to design the electrocatalyst with high activity, good conductivity, and satisfactory stability. In this work, nickel foam supported hierarchical Co9S8–Ni3S2 composite hollow microspheres were derived from in situ-generative MOF precursors and the subsequent sulfurization process by a simple two-step solvothermal method. The composite microspheres were directly grown on nickel foam without any binder, and nickel foam was used as the nickel source and support material. The morphology and constitution of the series self-supported electrodes were characterized by SEM, TEM, XRD, XPS, and Raman, respectively. The unique porous architecture enriched the electrode with sufficient active surface and helped to reactants and bubble evolved during electrochemical water oxidation. Through tuning the concentration of cobalt source and ligand, the content ratio of Co9S8 and Ni3S2 can be modulated. The heterostructures not only afford active interfaces between the phases but also allow electronic transfer between Co9S8 and Ni3S2. The optimized Co9S8-Ni3S2/NF-0.6 electrode with the highest electrochemical surface area and conductivity shows the best OER performance among the series electrodes in 1 M KOH solution. The overpotential of Co9S8-Ni3S2/NF-0.6 is only 233 mV when the current density is 10 mA cm−2, and corresponding Tafel slope is 116.75 mV dec−1. In addition, the current density of Co9S8-Ni3S2/NF-0.6 electrocatalyst hardly decreased during the 12 h stability measurement. Our approach in this work may provide the future rational design and synthesis of satisfactory OER electrocatalysts.

Cu-Co Hybrid Crystals Assembled on Hollow Microsphere: Temperature-Dependent Top-Down Synthesis and Aggregation-Induced Conversion from Microwave Shielding to Absorption.

The construction of hollow metallic microspheres with rationally designed building blocks of the metal shell is a promising way to achieve low density and functionality control, but the microengineering of the metallic structures on a micrometer spherical surface is a great challenge. In the present work, a novel and simple calcination-induced aggregation strategy is developed to realize the distribution status and microstructure control of Co-Cu bimetal building blocks assembled on a hollow glass microsphere support, and thus a series of low-density (0.58gcm-3 ) dual shell composite hollow microspheres are constructed with gradient in electromagnetic property depending on the calcination temperature (CT). The optimized microwave shielding performance can be achieved at a CT of 500°C, while further increasing CT to 700°C leads to an interesting conversion from microwave shielding to absorption with an optimized effective absorption bandwidth of 4.64GHz at a low matching thickness of 1.33mm. The mechanism underlying the CT-dependent metallic shell structure variation and further the decisive effect of the shell structure on the microwave response behavior are proposed based on a series of contrast experiments.

Controlled synthesis of β-Bi2O3/Bi2O2CO3 hollow microspheres with enhanced photocatalytic degradation of tetracycline under visible light

Well-dispersed β-Bi2O3/Bi2O2CO3 hollow microspheres were successfully synthesized by calcination an intermediate product fabricated via a solvothermal method using N, N-dimethyl formamide (DMF) as reaction media and carbon nanospheres as sacrifice templates. The molar ratio of β-Bi2O3 and Bi2O2CO3 in β-Bi2O3/Bi2O2CO3 composites can be adjusted by controlling the roasting conditions, which will influence the utilization of sunlight and the photo-induced charge carrier separation and transfer of the composites constructed, thus affecting photocatalytic activity. Experimental and characterization results suggest that the formation of the special structure could be ascribed to the interdiffusion of BiO+ and carbon chain during solvothermal reaction. Control experiments confirmed that as-prepared β-Bi2O3/Bi2O2CO3 composites possessed reliable photocatalytic activity and recycle stability for tetracycline degradation, achieving 95.34 % under Xe lamp irradiation for 60 min and without significant decrease after four cycles. Our findings provide another insight for the transformation of elemental bismuth into β-Bi2O3, and open up a general route for the synthesis of Bi2O2CO3-based composite hollow microspheres for water pollution control.

Novel TiO2 Nanoparticles/Polysulfone Composite Hollow Microspheres for Photocatalytic Degradation.

Nanosized titanium oxide (TiO2) material is a promising photocatalyst for the degradation of organic pollutants, whereas the difficulty of its recycling hinders its practical application. Herein, we reported the preparation of a novel titanium oxide/polysulfone (TiNPs/PSF) composite hollow microspheres by the combination of Pickering emulsification and the solvent evaporation technique and their application for the photodegradation of methyl blue (MB). P25 TiO2 nanoparticles dispersed on the surface of PSF microspheres. The porosity, density and photoactivity of the TiNPs/PSF composite microsphere are influenced by the TiO2 loading amount. The composite microsphere showed good methyl blue (MB) removal ability. Compared with TiO2 P25, and PSF, a much higher MB adsorption speed was observed for TiNPs/PSF microspheres benefited from their porous structure and the electrostatic attractions between the MB+ and the negatively charged PSF materials, and showed good degradation efficiency. For TiNPs/PSF composite microsphere with density close to 1, a 100% MB removal (10 mg L−1) within 120 min at a catalyst loading of 2.5 g L−1 can be obtained under both stirring and static condition, due to well dispersing of TiO2 particles on the microsphere surface and its stable suspending in water. For the non-suspended TiNPs/PSF composite microsphere with density bigger than 1, the 100% MB removal can be only obtained under stirring condition. The removal efficiency of MB for the composite microspheres retained 96.5%, even after 20 cycles. Moreover, this composite microsphere also showed high MB removal ability at acidic condition. The high catalysis efficiency, excellent reusability and good stability make this kind of TiNPs/PSF composite microsphere a promising photocatalyst for the water organic pollution treatment.

Rational design and facile hydrothermal-thermal conversion synthesis of hierarchical porous urchin-like Cu2−xSi2O5(OH)3·xH2O and CuO/SiO2 hollow microspheres for high efficiency catalytic reduction of nitroarenes and adsorption of organic dye

Hierarchical porous urchin-like Cu2−xSi2O5(OH)3·xH2O hollow microspheres constructed by radially aligned one-dimensional (1D) nanotubes (NTs) are rationally designed and facilely fabricated via a one-pot hydrothermal method (120 °C, 12.0 h) using abundant CuCl2·2H2O and Na2SiO3·9H2O as the basic raw materials, in the absence of any pre-prepared templates, additives or organic solvents. A probable etching formation mechanism of the Cu2−xSi2O5(OH)3·xH2O hollow microspheres assisted by the intermediate SiO2 nanospheres is proposed. The subsequent mild thermal conversion (750 °C, 2.0 h) results in CuO/SiO2 composite hollow microspheres. Both of the hierarchical porous Cu2−xSi2O5(OH)3·xH2O and CuO/SiO2 composite microspheres present highly catalytic activity to the reduction of the nitroarenes (e.g. 4-NP and 2-NP). Particularly, the hierarchical porous Cu2−xSi2O5(OH)3·xH2O hollow microspheres bearing high specific surface area (528.2 m2 g−1) and large pore volume (1.083 cm3 g−1) and in situ reduced highly dispersed metallic Cu0 demonstrate high activity for the 4-NP reduction, with an exceptional rate constant (Knor = 60.6 s−1 g−1) higher than that of many other previously reported results. The synergic effect of the in situ reduced Cu0 and hierarchical porous structures on the reduction of 4-NP has also been deliberately investigated. Moreover, the Cu2−xSi2O5(OH)3·xH2O and CuO/SiO2 composite microspheres have also displayed excellent recycling catalytic performance during the tested 10 successive runs of reduction of 4-NP without significant degradation in its activity. Additionally, the Cu2−xSi2O5(OH)3·xH2O microspheres also exhibit excellent adsorption performance for removal of cationic dye methylene blue (MeB), with the maximum adsorption capacity qm of 242.5 mg g−1. The hierarchical porous Cu2−xSi2O5(OH)3·xH2O and CuO/SiO2 composite microspheres thus demonstrate great potentials as low-cost, environmentally friendly and competitive candidates in future practical wastewater treatment.

Silicate–CoNi–carbon triple shell sandwich structured composite hollow microspheres with low density boosted microwave absorption and high mechanical strength

Low density silicate–CoNi–carbon triple shell hollow microspheres with high mechanical strength and controllable electromagnetic properties were prepared on a large scale.

Facile synthesis of uniform CuO/Cu2O composite hollow microspheres for a non-enzymatic glucose sensor

CuO/Cu2O composite hollow microspheres (HMs) were fabricated by a convenient and self-templated hydrothermal method with Cu(OAc)2 as precursor, and used as a non-enzymatic glucose sensor. The CuO/Cu2O HMs exhibited a wide detection range (from 10 μM to 3 mM ), low detection limit (0.04 μM) and high sensitivity (1762 μAmM 1 cm−2) which is superior to existing copper oxide. The excellent electrocatalytic activity was due to the high surface area, porosity and Cu2+/Cu+ redox couples. Moreover, the sensor shows high anti-interference ability, good reproducibility and stability which make it well reliable for determination of glucose in practical samples. This simple fabrication method will arouse interests in constructing other excellent-performance bi-component metal oxides for practical glucose sensing.

Photovoltaics literature survey (no. 149)

Photovoltaics literature survey (no. 149)

One-step synthesis of hierarchical SnO2/TiO2 composite hollow microspheres as an efficient scattering layer for dye-sensitized solar cells

Hierarchical SnO2/TiO2 composite hollow microspheres were synthesized via one-step hydrothermal route by using titanium tetrabutoxide as titanium source and potassium stannate and tripolycyanamide as co-additive, and the samples were characterized by XRD, BET, SEM and TEM measurements. The results denoted that the synthesized microspheres with a diameter of ca 500–1000 nm were assembled by thin nanosheets and possessed a large surface area of 199.3 m2 g−1. In addition, EDX and element mapping measurements indicated that a small amount of SnO2 nanoparticles uniformly distributed among the nanosheets of microspheres. The hierarchical microspheres simultaneously facilitated dye adsorption, light harvesting, and electron transport, giving rise to a high photovoltaic conversion efficiency of 8.70% when applied as scattering layer for dye-sensitized solar cells, which was a 28.1% improvement compared to that of bare nanocrystalline TiO2 (6.79%, Dyesol) based cell.

Controlled Synthesis of Heterostructured SnO2-CuO Composite Hollow Microspheres as Efficient Cu-Based Catalysts for the Rochow Reaction

In this work, we report the design and synthesis of a series of heterostructured SnO2-CuO hollow microspherical catalysts (H-SnO2(x)-CuO, x is the weight ratio of Sn/Cu) for the Rochow reaction. The microspherical catalysts with nanosheets and nanoparticles as building blocks were prepared by a facile one-pot hydrothermal method coupled with calcination. When tested for the Rochow reaction, the prepared H-SnO2(0.2)-CuO composite exhibited higher dimethyldichlorosilane selectivity (88.2%) and Si conversion (36.7%) than the solid CuO, hollow CuO and other H-SnO2(x)-CuO microspherical samples, because in the former there is a stronger synergistic interaction between CuO and SnO2.

In situ construction of hierarchical WO3/g-C3N4 composite hollow microspheres as a Z-scheme photocatalyst for the degradation of antibiotics

Elegant Z-scheme WO3/g-C3N4 composite hollow microspheres (CHMs) were constructed through precisely controlled in situ hydrolysis and a polymerization process consecutively. The formation of intact and well-defined hollow microspheres can be realized through optimizing the ratio of precursors for WO3 and g-C3N4. The shell of these hollow microspheres consist of well-distributed WO3 and g-C3N4 nanoparticles, and excellent heterojunctions with numerous interfaces and highly exposed oxidation-reduction active sites have thus been built. By virtue of this special architecture, more incident photons are expected to be trapped in the hollow cavities, which contribute to more electrons and holes available for photocatalytic reactions. Moreover, these photoinduced hole-electron pairs could be effectively separated, and the lifetime of charge carriers reaches 2.23ns, which is obviously prolonged compared with the WO3. WO3/g-C3N4 CHMs as an optimized Z-scheme system retains the original oxidation and reduction abilities for the components without change of the oxidation and reduction potential. Combined with the long survival time of holes and electrons, this photocatalyst showed enhanced degradation rates towards tetracycline hydrochloride (TC-HCl) and ceftiofur sodium (CFS).

Three dimensional graphene encapsulated ZnO-ZnFe2O4 composite hollow microspheres with enhanced lithium storage performance

In this work, ZnO-ZnFe2O4 composite hollow microspheres are synthesized firstly through a facile chemical liquid method combined with the subsequent calcination processing. After the tight decoration of three dimensional graphene sheets under the assistance of cetyltrimethyl ammonium bromide surfactant, the as-harvested graphene encapsulated ZnO-ZnFe2O4 composite hollow microspheres, as an anode for lithium ion batteries, deliver a relative high reversible capacity of 625mA h g−1 after discharged/charged 300 times at 100mAg−1 and a decent specific capacity of 461mA h g−1 even at a large current density of 1000mAg−1. The modification of three dimensional graphene sheets and the well-dispersed ZnFe2O4, as well as special hollow configuration are responsible for the outstanding electrochemical properties of ZnO-based composite microspheres.

Hierarchical flower-like C/NiO composite hollow microspheres and its excellent supercapacitor performance

Abstract Nickel (II) oxide (NiO) nanosheet grown on N-doped carbon hollow spheres (NiO/NCHS) with hierarchical pore structure are obtained via facile chemical bath deposition followed by calcination at 350 °C under nitrogen atmosphere. Phase structure measurements indicate that the material is composed of NiO and N-doped carbon. The NiO/NCHS composite exhibits a unique flower-like morphology, where ultrathin NiO nanosheets are vertically grown on the surface of NCHS. This hierarchical nanostructure is beneficial for facilitating electron and electrolyte ion transport and accelerating the reversible redox reaction. The specific capacitance of the NiO/NCHS composite (585 F g −1 at 1 A g −1 ) is higher than that of pure NiO particle (453 F g −1 at 1 A g −1 ). Meanwhile, the NiO/NCHS composite exhibits excellent rate performance and superior cycling stability over 6000 cycles. The enhanced supercapacitive performance of the NiO/NCHS nanocomposite indicates that it can be an appealing candidate electrode material for supercapacitors.

Silicate glass/Ni-NiO double shell composite hollow microspheres: Fast combustion synthesis and electromagnetic properties

Silicate glass/Ni-NiO double shell composite hollow microspheres (DSCHMs) were prepared in large scale though a fast sol combustion route. Single shell silicate glass hollow microspheres (SGHMs) were used as low density support of the Ni-NiO composite shell, which also serve as the robust first shell of the DSCHMs. Ni-NiO composite shells were assembled on the surface of the SGHMs through fast combustion of a precursor mixture containing nickel ions, organic fuels in air. The thickness of the Ni-NiO composite shell can be tuned simply by controlling the repeating times of the Ni-NiO shell assembly. The electromagnetic property and microwave absorption performance of the as-obtained DSCHMs were investigated, which exhibit strong dependence on the thickness of the Ni-NiO composite shell. This work provides a new strategy for the high efficient fabrication of composite particles through fast assembly of functional shells with tailored composition, structure and electromagnetic properties on large scale.

Lightweight glass/carbon composite hollow microspheres with intact shell and good thermal stability

Abstract This work proposed a facile strategy to prepare glass/carbon composite hollow microspheres with intact shell and good thermal stability by in-situ depositing resorcinol-formaldehyde (RF) on hollow glass microspheres (HGS) and subsequently heat-treated at 800 °C. The structure formation of glass/RF composite hollow spheres were investigated and the results indicated that growth of RF colloid nanospheres on HGS was promoted by assistance of cetyltrimethylammonium bromide (CTAB). RF transformed into carbon via thermal pyrolysis to release CO 2 , H 2 O and CH 4 at inert atmosphere. Meanwhile, RF protected HGS from structure thermal deformation and the thermal stability of HGS was enhanced. Thus, shell structure of formed glass/carbon composite hollow microspheres was intact. This method avoided the traditional procedure to prepare template in prior and subsequently remove it. The obtained glass/carbon composite hollow microspheres with lightweight property and thermal stability would be potentially used as thermal insulator in the fields of thermal protection.

Preparation of Epoxy Composite Hollow Microspheres (ECHM) Using Toluenesulfonyl Hydrazide (TSH) as Blowing Agent

SummaryThe epoxy composite hollow microspheres (ECHM) was prepared by single emulsion technique. Porofor Toluenesulfonyl hydrazide (TSH) 75 was used as blowing agent. Carbon black was used as filler for polyamide‐epoxy adduct matrix, which was reverted ratio of 1:2 epoxy to polyamide. The epoxy mixture (internal phase) was dropped and stirred into a heated corn oil (external phase) to form spherical droplets. These epoxy droplets underwent two simultaneous mechanisms of curing and foaming and became hollow microspheres. As expected, higher TSH content produced lower density of ECHM because of more expansion in ECHM. This fact was also evident from the size of hollow microspheres observed by using scanning electron microscope. In addition, high TSH content of 16 phr induced higher thermal properties of ECHM compared to those of ECHM using 8 phr and 12 phr TSH.

Synthesis of well-dispersed ZnO–Co–C composite hollow microspheres as advanced anode materials for lithium ion batteries

Well-dispersed ZnO–Co–C composite hollow microspheres exhibit excellent electrochemical properties when used as anode materials for lithium ion batteries.

Correction: A facile approach to fabrication of well-dispersed NiO–ZnO composite hollow microspheres

Correction for ‘A facile approach to fabrication of well-dispersed NiO–ZnO composite hollow microspheres’ by Qingshui Xie et al., RSC Adv., 2013, 3, 24430–24439.

Hierarchical porous C/MnO2 composite hollow microspheres with enhanced supercapacitor performance

Hierarchical porous C/MnO2 composite hollow microspheres exhibited excellent electrochemical performance for use as a supercapacitor electrode.