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The synthesis of hollow AlN microsphere was studied because of its potential applications in various areas associated with high surface area and lightweight. A combined technique of hydrothermal and carbothermal reduction–nitridation (CRN) was adopted to synthesize spherical precursor and to transform to AlN, respectively, using Al-nitrate, sucrose, and urea. The precursor having different morphology were obtained after hydrothermal treatments at 180 °C for 12 h, depending on starting material combinations, where urea/Al molar ratio = 1 resulted in amorphous hollow microsphere. By CRN at 1500 °C for 4 h in a flowing N 2 atmosphere, approximately 5 μm-sized hollow microsphere composed of AlN, α -Al 2 O 3 , or γ -AlON could be synthesized. CRN at higher temperature (1600 °C for 4 h) or for longer holding time (1500 °C for 10 h) is required to obtain pure AlN microsphere. Further tests at nine different hydrothermal conditions were performed to find an optimal synthesis condition, while the possible formation mechanism for hollow AlN microspheres was also proposed based on observations. [ABSTRACT FROM AUTHOR]

[Display omitted] • MnO X catalysts with tunable morphology and oxygen vacancy defects were prepared. • Tailoring the morphology of MnO X can greatly improve the catalytic activity. • The oxygen vacancy defect on MnO X can expedite the activation-oxidation of toluene. To clarify the key role of oxygen vacancy defects on enhancing the oxidative activity of the catalysts, metal–organic frameworks (MOFs) derived MnO X catalysts with different morphologies and oxygen vacancy defects were successfully prepared using a facile in-situ self-assembly strategy with different alkali moderators. The obtained morphologies included three-dimensional (3D) triangular cone stacked MnO X hollow sphere (MnO X -H) and 3D nanoparticle stacked MnO X nanosphere (MnO X -N). Compared to MnO X -N, MnO X -H exhibited higher activity for the oxidation of toluene (T 90 = 226 °C). This was mainly due to the large number of oxygen vacancy defects and Mn4+ species in the MnO X -H catalyst. In addition, the hollow structure of MnO X -H not only facilitated toluene adsorption and activation of toluene and also provided more active sites for toluene oxidation. Reaction mechanism studies showed that the conversion of toluene to benzoate could be realized over MnO X -H catalyst during toluene adsorption at room temperature. In addition, abundant oxygen vacancy defects can accelerate the activated oxidation of toluene and the formation of oxidation products during toluene oxidation. [ABSTRACT FROM AUTHOR]

Morphology control and hydrophilic modification are important strategies to improve the photocatalytic activity of polymers. In the present work, novel conjugated microporous polymers with hollow spherical structures (CMPs-HSs) are prepared using 1,3,5-triacetylene benzene and 2,8-dibromodibenzothiophene as monomers through Sonogashira-Hagihara cross-coupling reaction and hard template method. In order to improve the dispersibility of the as-prepared CMPs-HSs in water, the hydrophilic modification of the CMPs-HSs is performed based on the thiol-alkynes click reaction, and the corresponding hydrophilic modified polymer is denoted as CMPs-HSs-S. The band gaps of CMPs-HSs and CMPs-HSs-S are 2.15 and 1.96 eV, respectively. The photocatalytic degradation rate of CMPs-HSs-S to Rhodamine B (RhB 20 mg L-1) is 90% within 80 min, while the CMPs-HSs is only 59%. Under the same experimental conditions, the degradation rate of CMPs-HSs-S to methylene blue (MB 20 mg L-1) is 85% within 120 min, and the degradation rate of CMPs-HSs to methylene blue is only 41%. The results of photocatalytic experiments show that the photocatalytic performance of CMPs-HSs-S is significantly better than that of CMPs-HS, suggesting that hydrophilic modification is more conducive to the contact of CMPs-HSs-S with pollutants and the occurrence of a photodegradation reaction. In addition, the corresponding composite membrane materials (abbreviated as CCMPs-MHSs and CCMPs-MHSs-S) of the CMPs-HS and CMPs-HS-S were prepared by the method of carbonized treatment, and their solar-driven interfacial evaporation (SDIE) performance was also studied. Under 1 kW m-2 simulated sunlight irradiation, the solar evaporation rates of CCMPs-MHSs and CCMPs-MHSs-S are 1.38 and 1.41 kg m-2 h-1 and the photothermal conversion efficiencies are 81.5 and 84.6%, respectively. Therefore, considering the designable flexibility of CMPs, the CMPs-based novel materials have great application potential in the study of photodegradation of organic dyes, solar-driven interfacial evaporation, etc. [ABSTRACT FROM AUTHOR]

A uniform dispersion of TiO2/SiO2 hollow nanosphere of 290 nm with a high surface area of more than 100 m2g− 1 is prepared using polystyrene spheres as templates after calcination at 600 °C. The TiO2/SiO2 hollow nanospheres are characterized by scanning electron microscopy, transmission electron microscopy, dynamic light scattering, nitrogen adsorption-desorption isotherms, and X-ray diffraction. The TiO2/SiO2 hollow nanospheres are shown to be highly effective in selectively enriching phosphopeptides, resulting in a significant reduction of non-phosphorylated species and an enhanced presence of modified peptides. The favorable results obtained in the present study for the enrichment of phosphoprotein β-casein pave the way toward a similar treatment of other types of biomolecules. [ABSTRACT FROM AUTHOR]

In this research TiO2 hollow spheres (HSs) were prepared using hydrothermally grown carbon spheres as the templates through a sol gel, liquid phase deposition method followed by an annealing process. Then they were introduced to another hydrothermal process for a controlled growth of the TiO2 branches on their surface. The synthesized branched HSs were deposited on a nanocrystalline TiO2 sublayer and formed an effective light scattering film in the photoelectrode of corresponding quantum dot sensitized solar cells (QDSCs). This could majorly increase the light traveling path inside the light absorbing quantum dots sensitizing layers and increase the power conversion efficiency. Three types of photoelectrodes including TiO2 NCs/CdSeTe sensitizing QDs/ZnS, TiO2 NCs/TiO2 HSs/CdSeTe QDs/ZnS and TiO2 NCs/TiO2 branched HSs/CdSeTe QDs/ZnS were fabricated and applied in QDSCs. The alloyed CdSeTe quantum dots (QDs) were synthesized through organometallic approach in high temperature with an absorption edge located around 800 nm. The corresponding bandgap energy is consequently appropriate for light absorption in visual-near IR region. The selection of hyperbranched TiO2 HSs with different dimensions of branches was so carried out to make the maximum QDs loading. Based on the findings, thepower conversion efficiency of the QDSC with TiO2NCs/TiO2 HSs/CdSeTe photoanode was measured about 4.8%. This efficiency was enhanced to 6.1% for the improved cell with a TiO2 NCs/branched TiO2 HSs/CdSeTe QDs/ZnS photoanode including light scatterer branched structures prepared at 3 h of the second hydrothermal branching stage. The reason was attributed to the higher level of light scattering and better QDs loading in modified photoanode due to shape and higher surface area of the branched TiO2 HSs. [ABSTRACT FROM AUTHOR]

ABSTRACTThe control incorporation of metals in silica hollow spheres (SHSs) may bring new functions to silica mesoporous structures for applications including catalysis, sensing, molecular delivery, adsorption filtration, and storage. However, the strategies for incorporating metals, whether through pre-loading in the hollow interior or post-encapsulation in the mesoporous shell, still face challenges in achieving quantitative doping of various metals and preventing metal aggregation or channel blockage during usage. In this study, we explored the doping of different metals into silica hollow spheres based on the dissolution-regrowth process of silica. The process may promote the formation of more structural defects and functional silanol groups, which could facilitate the fixation of metals in the silica networks. With this simple and efficient approach, we successfully achieved the integration of ten diverse metal species into silica hollow sphere (SHS). Various single-metal, dual-metal, triple-metal, and quadruple-metal doped SHSs have been prepared, with the doped metals being stable and homogeneously dispersed in the structure. Based on the structural characterizations, we analyzed the influence of metal types on the morphology features of SHSs. The synergistic effects of multi-metals on the catalysis applications were also studied and compared.

Doping and hybridization with other semiconductors are highly effective ways to address the limitations, including their weak response to visible light and significant recombination of photogenerated carriers. In addition, the assisted carbon on the catalyst surface and the structural design have the advantage of being catalytically active. Herein, visible-light-active N-doped C/Na2Ti6O13/TiO2 hollow spheres (denoted as N–C/NTO/TiO2 HS) were successfully prepared using a facile two-step method and evaluated for methylene blue (MB) aqueous solution degradation under visible-light irradiation.The as-obtained N–C/NTO/TiO2 HS demonstrated improved photocatalytic efficiency (94 %) and pseudo-first-order kinetic degradation rate (0.023 min−1). Moreover, after three cycles of testing, N–C/NTO/TiO2 HS showed a 91 % degradation rate in its photostability. The enhanced photocatalytic performance was attributed to the combined effects of N-doping, carbon species on the surface, and the coupling of TiO2 and Na2Ti6O13 using morphology engineering. Finally, based on the experimental results, a possible photocatalytic mechanism was proposed. This study provides a rational approach toward the development of high-performance titanate-based photocatalysts for solar energy-assisted wastewater treatment.

Visible-light-driven N2 reduction into NH3 in pure H2O provides an energy-saving alternative to the Haber–Bosch process for ammonia synthesizing. However, the thermodynamic stability of N≡N and low water solubility of N2 remain the key bottlenecks. Here, we propose a solution by developing a WO3−x hollow sphere with oxygen vacancies. Experimental analysis reveals that the hollow sphere structure greatly promotes the enrichment of N2 molecules in the inner cavity and facilitates the chemisorption of N2 onto WO3−x-HS. The outer layer's thin shell facilitates the photogenerated charge transfer and the full exposure of O vacancies as active sites. O vacancies exposed on the surface accelerate the activation of N≡N triple bonds. As such, the optimized catalyst shows a NH3 generation rate of 140.08 μmol g−1 h−1, which is 7.94 times higher than the counterpart WO3-bulk. [ABSTRACT FROM AUTHOR]

In this study, lightweight cordierite-mullite ceramics with high strength and high thermal-shock resistance were successfully synthesized by solid-state method with the usage of hollow ceramic microspheres. After careful physico-chemical and mechanical characterization, we gained an economical cordierite material with a low bulk density of 1.40 g/cm3 with an apparent porosity of 44.78%, a flexural strength of 20.17 MPa and a coefficient of thermal expansion of 2.26 × 10−6 oC−1 compared to the bulk counterpart with a bulk density of 2.00 g/cm3 with an apparent porosity of 25.75%, a flexural strength of 23.69 MPa and a coefficient of thermal expansion of 2.47 × 10−6 oC−1. As a catalyst support of Na-FeO x , the economical cordierite has proved the same stability and activity in CO 2 hydrogenation towards C 5+ fuels as bulk cordierite-based catalyst counterparts. [ABSTRACT FROM AUTHOR]

In this work, a series of the Cu 2 O/CuO hollow sphere heterojunction catalysts with various Cu+/Cu2+ ratios were designed and synthesized to improve the low-temperature catalytic activity of CO oxidation. The physicochemical properties of all the catalysts were characterized by the SEM, TGA, N 2 -physisorption, XRD, FT-IR, XPS, and H 2 -TPR. The results revealed that the Cu 2 O hollow sphere catalyst had the large specific surface area due to the formation of the hollow structure, which could provid more accessible active sites for the gaseous reactants. Meanwhile, the Cu 2 O/CuO hollow sphere heterojunction catalysts possessed high concentration of the surface oxygen vacancies and further promoted the adsorption and activation of O 2. As a result, the apparent activation energy of the CO oxidation was decreased and thus low-temperature activity of the CO oxidation was finally promoted. Therefore, the Cu 2 O/CuO hollow sphere heterojunction catalysts were considered as a series of high-efficient catalyst candidates for CO oxidation with promising low-temperature performance. [Display omitted] • The Cu 2 O hollow sphere catalyst is facilely synthesized by the one-pot strategy. • The Cu 2 O/CuO heterojunction catalysts with adjustable surface Cu+/Cu2+ ratio. • The Cu 2 O/CuO-HS-T catalysts exhibit high surface oxygen vacancy concentration. • The Cu 2 O/CuO-HS-T catalysts enhance the low-temperature activity of CO oxidation. [ABSTRACT FROM AUTHOR]

MnZn ferrite precursor powders were prepared by the nano in situ composite method. Three surfactants, which include polyethylene glycol 400 (PEG-400), cetyltrimethyl ammonium bromide (CTAB), and sodium dodecyl sulfate (SDS), were usedM and the impact of the surfactants on the precursor sol solutions and precursor powders was studied. X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy, a field emission scanning electron microscope (FE-SEM), a transmission electron microscope (TEM), a Zeta potential meter, a BET surface analyzer, and a vibrational sample magnetometer (VSM) were used to characterize the precursor sol solutions and the precursor powders. The results showed that these surfactants can improve the dispersion state and Zeta potentials of sol particles and increase the specific surface areas of the precursor powders. Moreover, the precursor powders were composed of MnZn ferrite, and some were amorphous. CTAB was the optimum surfactant and the zeta potential of the sol particles and the specific surface area of the precursor powders named P-0.1CTAB are 10.7 mV and 129.07 m2/g, respectively. In addition, the nano-particles that were made up of the P-0.1CTAB precursor powders had smaller sizes and more uniform particle distributions than the others. The magnetic properties' improvement was attributed to the addition of surfactants, and CTAB is the optimal type. In addition, the novel nano in situ composite method will inspire fresh thinking and investigation into the research of ferrite. [ABSTRACT FROM AUTHOR]

In this paper, we investigate the fundamental characteristics of plasticity in microheterogeneous continuum materials. Plasticity in such materials is a multiscale phenomenon with contrasting characteristics at different scales. A hollow sphere model, including a matrix embedding an oblate spheroidal pore, is considered as a sample representative elementary volume (REV) of a microheterogeneous material where, at the local level (microscale), a simple Drucker–Prager plasticity model is assumed for the matrix obeying the classical continuum theory of plasticity. The plasticity model is Lode angle independent with associated plastic flow and no hardening. We perform finite element numerical simulations on the REV to investigate the characteristics of the homogenized plasticity of the REV. It is seen that the homogenized plasticity shows complex characteristics such as Lode angle dependency, presence of cap, hardening, and nonassociativity. Well-established as these aspects are in the literature, they are often presumed in the plasticity models of heterogeneous materials in an ad hoc form. In contrast, we present here a systematic and lucid way to capture these aspects as emergent phenomena of heterogeneous microstructures. This has crucial implications in guiding the theoretical constitutive developments for elastoplastic materials toward adopting a multiscale approach that properly considers the effect of microstructure and naturally captures these aspects without the need for ad hoc assumptions. A fundamental assumption in the classical theory of plasticity is the plastic flow rule postulate, which states that the direction of plastic strain increment is governed only by the current state variables, independent of the loading increment direction. We show, through a stress probing exercise in 3D principal stress space, that the flow rule, assumed for the microscale plasticity, is not valid for the macroscopic plasticity. Indeed, the homogenized plastic flow direction in heterogeneous materials is governed by the current state variables and loading increment direction. Finally, we show that the plastic response is also a function of the stress path taken prior to loading. As such, nonclassical characteristics are observed for the plasticity of microheterogeneous materials. These nonclassical characteristics for the simple REV considered in this work (the hollow sphere model) align with some of the results observed in experiments or only reported for microdiscrete materials; herein, we show they are also valid for a broader range of materials endowed with microstructure, i.e., microcontinuous materials, and, as such, the fundamental assumptions in the classical theory of plasticity require revision before being applicable to the plastic behavior of heterogeneous materials. [ABSTRACT FROM AUTHOR]

Visible-light-driven N2 reduction into NH3 in pure H2O provides an energy-saving alternative to the Haber–Bosch process for ammonia synthesizing. However, the thermodynamic stability of N≡N and low water solubility of N2 remain the key bottlenecks. Here, we propose a solution by developing a WO3−x hollow sphere with oxygen vacancies. Experimental analysis reveals that the hollow sphere structure greatly promotes the enrichment of N2 molecules in the inner cavity and facilitates the chemisorption of N2 onto WO3−x-HS. The outer layer’s thin shell facilitates the photogenerated charge transfer and the full exposure of O vacancies as active sites. O vacancies exposed on the surface accelerate the activation of N≡N triple bonds. As such, the optimized catalyst shows a NH3 generation rate of 140.08 μmol g−1 h−1, which is 7.94 times higher than the counterpart WO3-bulk.

The experimental and simulationn investigation on the thermal and mechanical properties for the hollow sphere reinforced AZ31 magnesium matrix composite were carried out in this paper. The Split-Hopkinson Pressure Bar and thermal conductivity experiments were used to obtain the mechanical and thermal properties of the composite. MgO coating was used on the surface of the hollow sphere in order to prevent the reaction between hollow spheres and magnesium alloy matrix. 40% volume fraction of the hollow sphere with 3.6 mm diameter and 0.185 wall thickness was proven to have the best performance on both thermal and mechanical properties. [ABSTRACT FROM AUTHOR]

In this technical note, we add to the literature the analytical solution of the heat equation with radiation boundary conditions for an instantaneous point source in a hollow sphere. Instead of using the conventional method of the Laplace transfer and inverse Laplace transfer that requires intricate integral in the complex plane, we present a new approach to derive the analytical solution in the time domain. First, we express the instantaneous point source as the initial condition in terms of Dirac delta, e.g., Eq. (2), which is further expressed in the form of the general solution, i.e., Eq. (18). Subsequently, we determine the solution coefficients and obtain the analytical solution. Two special cases with prescribed surface temperature and no-flux boundaries are presented to demonstrate the solution. This solution is of practical importance in many scientific and engineering applications, such as pore pressure prediction in reservoir engineering, thermal analysis of casing in drilling engineering, and determining the relaxation process in nuclear magnetic resonance (NMR). [ABSTRACT FROM AUTHOR]

The best use of photogenerated electrons and holes is crucial to boosting photocatalytic activity. Herein, a bifunctional dual‐cocatalyst‐modified photocatalyst is constructed based on CdS/MoO2/MoS2 hollow spheres for hydrogen evolution coupled with selective pyruvic acid (PA) production from lactic acid (LA) oxidation. MoS2 and MoO2 are simultaneously obtained from the conversion of CdMoO4 in one step. In a photocatalytic process, the MoS2 and MoO2 function as the reduction and oxidation centers on which photogenerated electrons and holes accumulate and are used for hydrogen evolution reaction (HER) and PA synthesis, respectively. By monitoring the intermediates, a two‐step single‐electron route for PA production is proposed, initiated by the cleavage of the α‐C(sp3)−H bond in the LA. The conversion of LA and the selectivity of PA can reach ca. 29 % and 95 % after a five‐hour reaction, respectively. [ABSTRACT FROM AUTHOR]

Tb-doped TiO2 (anatase) micro-hollow spheres (HSs) with nano-shells, in the range 0.00–3.00 at.% Tb, were successfully synthesized by a simultaneous chemical implantation route of both Ti and Tb cations from chlorides to a poly-styrene (PST)-co-poly-divinyl benzene (PDVB) sacrificial template, followed by controlled hydrolysis and polycondensation reactions. After water addition to the mixture of the precursors with the template, a decrease in the intensity and a shift to lower wavenumbers of the C=O absorption band in the IR spectra can indicate not only the anchoring of Ti and Tb ions to the carbonyl group of the template but also the hydrolysis of the implanted precursors. This latter process can involve a proton attack on the Ti–Cl, Tb–Cl and C=O bonds, the occupation of a vacant site by a water molecule, and then the dissociation of the dangling Ti–Cl, Tb–Cl ligands and C=O bonds. It gives rise to Ti1−xTbx[(OH)4−uClv]@PST–PDVB and Ti1−xTbx[(OH)4−y]@PST–PDVB complexes (x = 0.00, 0.0012, 0.0170 and 0.030). Finally, polycondensation of these species leads to Ti1−xTbxO2−w′@PST–PDVB compounds. After subsequent thermal removal at 550 °C of the template, the IR bands of the core (template) totally vanished and new bands were observed in the 400–900 cm−1 region which can be attributed to the metalloxane bondings (M–O, M'–O, M–O–M, M–O–M' and/or M'–O–M', being M and M' = Ti and Tb, respectively, i.e., mainly vibration modes of anatase). Then, micron-sized HSs of TiO2 and Tb-doped-TiO2 (anatase) were obtained with nano-shells according to field emission gun scanning electron microscopy (FEG-SEM) and transmission electron microscopy (TEM) observations. Furthermore, X-ray photoelectron spectroscopy (XPS) measurements confirmed the presence of Tb4+ (38.5 and 41.2% for 1.70 and 3.00 at.% Tb, respectively) in addition to Tb3+ in the resulting HSs, with increasing Tb4+ content with both Tb doping and higher calcination temperatures. Then, these HSs can be considered as rare earth (RE) co-doped systems, at least for 1.70 and 3.00 at.% Tb contents being the transition to rutile phase favored by Tb doping for those compositions. Finally, diffusion of Tb from the inner parts to the surface of the HSs with the calcination treatments was also observed by XPS. [ABSTRACT FROM AUTHOR]

N-butanol is a harmful volatile gas, so creating an appropriate n-butanol sensor is critical for preserving human health and the manufacturing environment. In contrast to single metal oxide semiconductors, multicomponent metal oxides, especially perovskite ternary metal oxides with the ABO 3 structure, exhibit significant potential for development owing to their precise structures and diverse physicochemical properties. In this paper, three-dimensional porous hollow spheres PrFeO 3 were synthesized by combining air annealing and hydrothermal techniques. The crystal structure, surface composition, chemical state, and morphology of PrFeO 3 materials were evaluated using several kinds of characterization approaches. The gas sensitivity of PrFeO 3 materials was also thoroughly explored. The results show that at the optimal working temperature of 280 ℃, the PrFeO 3 material excels in n-butanol gas sensing, with a response of 85 for 100 ppm n-butanol. Additionally, the sensor demonstrates high selectivity for n-butanol gases, low concentration detection capability, outstanding repeatability, rapid reaction recovery time (18 s/13 s), long-term stability, and exceptional reproducibility. The unique morphology and high oxygen vacancy content of PrFeO 3 provide numerous active sites on its surface, promoting the adsorption and desorption of n-butanol gas molecules and enhancing its gas-sensitive properties. • PrFeO 3 material with three-dimensional porous hollow spheres has been successfully synthesized by a combination of hydrothermal and air annealing methods. • The gas sensitivity of PrFeO 3 material to n-butanol has been investigated for the first time. • PrFeO 3 sensor exhibits high selectivity and fast response recovery time to detecting n-butanol. • The baseline of the PrFeO 3 sensor remains stable throughout the gas sensitivity test, demonstrating excellent reversibility. [ABSTRACT FROM AUTHOR]

[Display omitted] • Successful manufacturing of CuSn-Fe hollow spheres syntactic foams by a novel infiltration method. • Improvement of the compressive behavior for the syntactic foams due to the transformation of ε into β phase. • Excellent matrix-reinforcement bonding due to CuSn intergranular infiltration in the sphere walls. • The absence of interfacial products during the infiltration process. This work analyzes the manufacturing process, phase transformations and compression behavior of un-treated and heat-treated syntactic foams consisting of a Cu20Sn alloy matrix reinforced with Fe-hollow spheres. Manufacturing process included the infiltration of the molten alloy into preforms of spheres sintered at 1000 °C during 1 h, obtaining syntactic foams with porosities near 52 %. These foams were heat-treated at 750 °C for 1 h, followed by quenching in water, which led to phase transformations from ε to β. This fact improved the compressive properties of the foams, increasing compression strengths from 195 to 243 MPa. Interfaces were not found between matrix and the Fe-hollow spheres. [ABSTRACT FROM AUTHOR]

Supercapacitors have emerged as versatile energy storage devices, valued for their rapid charge-discharge capabilities and long cycle life. Concurrently, efficient electrocatalysts are essential for promoting the oxygen evolution reaction (OER) in sustainable energy applications. Inevitably, this study explores the integration of a Cobalt-Nickel (Co/Ni) based metal-organic framework [CoNi((μ 3 -tp) 2 (μ 2 -py) 2 or CNTP] with ZnFe 2 O 4 hollow spheres (ZHS) to create innovative CNTP/ZHS nanocomposites tailored for supercapacitor and electrocatalytic OER applications. Different weight percentages of CNTP/ZHS nanocomposites were synthesized through a facile and scalable method, and their electrochemical performance was rigorously assessed. Electrochemical characterization revealed that a 40 wt percentage CNTP/ZHS (40-CNTP/ZHS) electrode demonstrated a very high specific capacitance of 1519.2 Fg−1 at 1 Ag−1 and retained 92.6 % of its specific capacitance after 10000 cycles. Moreover, it delivered remarkably high specific capacitance (447.2 Fg−1) and energy density (62.1 WhKg−1) along with outstanding cyclic stability (97.5 % after 5000 galvanostatic charge-discharge cycles). It also exhibited excellent OER activity, with a very low overpotential (207 mV to attain a current density of 10 mAcm−2), a small Tafel slope (66.5 mVdec−1), and high stability over 2000 cyclic voltammetry cycles. These characteristics underscore the significant potential of renewable energy technologies, particularly for water electrolysis and sustainable energy conversion. 1 1 OER, oxygen evolution reaction; tp, terephthalic acid; pyz = pyrazine; CNTP, CoNi((μ 3 -tp) 2 (μ 2 -pyz) 2 ; ZHS, ZnFe 2 O 4 hollow spheres; MOF, metal-organic framework; RHE, reversible hydrogen electrode; PEG-600, polyethylene glycol 600; EIS, electrochemical impedance spectroscopy; GCD, galvanostatic charge-discharge; CV, cyclic voltammetry; PVDF; polyvinylidene fluoride; NMP, N -methyl-2-pyrrolidone; SSC, symmetric supercapacitor; LSV, linear sweep voltammetry; ECSA, electrochemical active surface area; XRD, X-ray diffraction; EDS, energy-dispersive spectroscopy; XPS, X-ray photoelectron spectroscopy; FWHM, full width at half maximum; FTIR, Fourier-transform infrared; DRS, diffusion reflectance spectroscopy; FE-SEM, field emission scanning electron microscopy; FE-TEM, field emission transmission electron microscopy; HR-TEM, high-resolution transmission electron microscopy; XPS, X-ray photoelectron spectroscopy; PL, photoluminescence; ASC, asymmetric supercapacitor. [Display omitted] • CNTP/ZHS nanocomposites synthesized for OER and supercapacitor applications. • 40-CNTP/ZHS electrode exhibits high specific capacitance (1519.2 Fg−1). • Outstanding cyclic stability (92.6 % retention after 10000 cycles). • Symmetric supercapacitor with 40-CNTP/ZHS achieves high energy density (62.1 WhKg-1). • Low OER overpotential (207 mV for 10 mAcm–2), small Tafel slope (66.5 mVdec–1). [ABSTRACT FROM AUTHOR]

The remarkable application of tin oxide in various domains is indebted to its photoelectronic merits. However, significant efforts to discover its photocatalytic potential were restricted through arduous challenges, which were the amelioration of light-harvesting and -utilizing. In fact, the uncommon light absorption energy has drawn veil over the brilliance of astounding oxidation potential, which is much more than that of TiO 2. Herein, our attention was focused on the taking advantages of self-template structure for simultaneously enjoying the two sides of photoelectronic justification as well as the S-step system for eminent charge dissociation. In this regard, the optimized Cu-modified SnO 2 yolk-shell ((5)YS-CuSnO) spheres were engineered through the copper modulation into glycerate-assisted metal-organic structure. As a result, the exceptional light-harvesting was achieved through desirable defects and oxygen vacancy resulted from Cu-doping, and also efficient light-utilization was obtained by the multi-scattering/reflection effect resulted from multi-shell configuration. After the effectual incorporation (40 wt⁒) of (5)YS-CuSnO was encapsulated into the V 2 O 5 -decorated wrinkled g-C 3 N 4 lamella (VO–WCN), the dual S-step VO-WCN@(5)YS-CuSnO introduced unprecedented levofloxacin (LFC) decontamination performance, which was kinetically 5.2 and 30.2-times greater than of the (5)YS-CuSnO and bare SnO 2 yolk-shell. The conspicuous fulfillment of nanocomposite was manifested in the LFC mineralization, pharmaceutical effluent treatment within 360 min, and successive cycling reactions. The fusion of the extraordinary architecture of YS-CuSnO with S-Step system not only initiates the facile and practical photocatalytic exploitation, but shade light on some undeveloped side of tin oxide. [Display omitted] • The optimized Cu-modified SnO 2 yolk-shell ((5)YS-CuSnO) spheres were engineered through the copper modulation into glycerate-assisted metal-organic structure. • The encapsulation of (5)YS-CuSnO into the V 2 O 5 -decorated wrinkled g-C 3 N 4 lamella (VO–WCN) introduced the dual S-step VO-WCN@(5)YS-CuSnO • The ternary nanostructure demonstrated ultramost photocatalytic efficiency toward totoal levofloxacin decomposition. • The sufficient perforemce of levofloxacin mineralization and real pharmaceutical wastewater demonstrated highly oxidative photocatalytic system. • Consecutive cycling experiment together with scrutinization of post-characterization analyses confirmed a highly stable structure. [ABSTRACT FROM AUTHOR]

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Seawater electrolysis is an attractive technique for mass production of high‐purity hydrogen considering the abundance of seawater. Nevertheless, due to the complexity of seawater environment, efficient anode catalyst, that should be, cost effective, highly active for oxygen evolution reaction (OER) but negligible for Cl2/ClO– formation, and robust toward chlorine corrosion, is urgently demanded for large‐scale application. Although catalysis typically appears at surface, while the bulk properties and morphology structure also have a significant impact on the performance, thus requiring a systematic optimization. Herein, a multiscale engineering approach toward the development of cost‐effective and robust OER electrocatalyst for operation in seawater is reported. Specifically, the engineering of hollow‐sphere structure can facilitate the removal of gas product, while atom‐level synergy between Co and Fe can promote Co sites transforming to active phase, and in situ transformation of sulfate ions layer protects catalysts from corrosion. As a result, the as‐developed hollow‐sphere structured CoFeSx electrocatalyst can stably operate at a high current density of 100 mA cm–2 in the alkaline simulated seawater (pH = 13) for 700 h and in a neutral seawater for 20 h without attenuation. It provides a new strategy for the development of electrocatalysts with a broader application potential. [ABSTRACT FROM AUTHOR]

In this study, pure zinc stannate (ZnSnO3) and bismuth (Bi)-doped ZnSnO3 composites (Bi-ZnSnO3) were synthesized via the in situ precipitation method, and their microstructures, morphologies, chemical components, sizes, and specific surface areas were characterized, followed by testing their gas sensing properties. The results revealed that Bi-ZnSnO3 showed superior gas sensing properties to n-butanol gas, with an optimal operating temperature of 300 °C, which was 50 °C lower than that of pure ZnSnO3. At this temperature, moreover, the sensitivity of Bi-ZnSnO3 to n-butanol gas at the concentration of 100 ppm reached as high as 1450.65, which was 35.57 times that (41.01) of ammonia gas, 2.93 times that (495.09) of acetone gas, 6.02 times that (241.05) of methanol gas, 2.54 times that (571.48) of formaldehyde gas, and 2.98 times that (486.58) of ethanol gas. Bi-ZnSnO3 had a highly repeatable performance. The total proportion of oxygen vacancies and chemi-adsorbed oxygen in Bi-ZnSnO3 (4 wt%) was 27.72% to 32.68% higher than that of pure ZnSnO3. Therefore, Bi-ZnSnO3 has considerable potential in detecting n-butanol gas by virtue of its excellent gas-sensing properties. [ABSTRACT FROM AUTHOR]

Biopolymer hollow spheres have shown great promise for wastewater treatment due to their unique structure and properties. However, challenging issues like low efficiency and poor recyclability still exist for most hollow spheres. In this study, the modification of chitosan/carboxymethyl cellulose (CS/CMC) with Fe3O4 nanoparticles for the formation of bifunctional CS/CMC-Fe3O4 hybrid hollow spheres were prepared using a facile two stage mixing route, which exhibited excellent adsorption and catalytic degradation of dyes. The removal ability of the synthesized hollow spheres towards acid blue-113 (AB) and reactive orange C-3R (RO) using persulfate oxidation system was greatly improved compared with single adsorption or catalysis. The removal ratio of AB and RO could reach up to 96.2 and 97.5%, respectively. The kinetic process conformed to the quasi-second-order kinetics and the adsorption process was the controlling step of dye removal. In addition, the created hollow spheres showed excellent environmental adaptability and regenerative capability. This study provides a convenient and practical method for catalyst loading on biomass hollow spheres, which has perspective applications in wastewater purification. [ABSTRACT FROM AUTHOR]

A heterogeneous catalyst CuO–CeO2 with a hollow structure was successfully synthesized by assembling CuO on the outer surface of CeO2 hollow spheres through a layer-by-layer deposition strategy. Further reduction under a H2 atmosphere was carried out to modify its surface state, resulting in sample r-CuO–CeO2. The catalysts were characterized by X-ray diffraction, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and Fourier transform-infrared spectroscopy (FT-IR). SEM and TEM showed that the synthesized catalysts had a hollow sphere structure, which can expose more active sites and promote mass transfer. The results of XPS revealed that the content of Cu0&Cu+ increased from 13.6 to 19.0% after H2 reduction, which was conducive to the activation of terminal alkyne to promote the annulation/A3-coupling reaction. The conversion of this cascade reaction with the r-CuO–CeO2 catalyst can reach more than 95%, while the value was only 55% by using CuO–CeO2 as a catalyst. Moreover, the r-CuO–CeO2 catalyst showed a good recycle property and group compatibility in the general applicability of the cascade annulation/A3-coupling reaction, providing a series of propargylamine derivatives in good chemoselectivity. [ABSTRACT FROM AUTHOR]

Abstract Seawater electrolysis is an attractive technique for mass production of high‐purity hydrogen considering the abundance of seawater. Nevertheless, due to the complexity of seawater environment, efficient anode catalyst, that should be, cost effective, highly active for oxygen evolution reaction (OER) but negligible for Cl2/ClO– formation, and robust toward chlorine corrosion, is urgently demanded for large‐scale application. Although catalysis typically appears at surface, while the bulk properties and morphology structure also have a significant impact on the performance, thus requiring a systematic optimization. Herein, a multiscale engineering approach toward the development of cost‐effective and robust OER electrocatalyst for operation in seawater is reported. Specifically, the engineering of hollow‐sphere structure can facilitate the removal of gas product, while atom‐level synergy between Co and Fe can promote Co sites transforming to active phase, and in situ transformation of sulfate ions layer protects catalysts from corrosion. As a result, the as‐developed hollow‐sphere structured CoFeSx electrocatalyst can stably operate at a high current density of 100 mA cm–2 in the alkaline simulated seawater (pH = 13) for 700 h and in a neutral seawater for 20 h without attenuation. It provides a new strategy for the development of electrocatalysts with a broader application potential.

MnZn ferrite precursor powders were prepared by the nano in situ composite method. Three surfactants, which include polyethylene glycol 400 (PEG-400), cetyltrimethyl ammonium bromide (CTAB), and sodium dodecyl sulfate (SDS), were usedM and the impact of the surfactants on the precursor sol solutions and precursor powders was studied. X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy, a field emission scanning electron microscope (FE-SEM), a transmission electron microscope (TEM), a Zeta potential meter, a BET surface analyzer, and a vibrational sample magnetometer (VSM) were used to characterize the precursor sol solutions and the precursor powders. The results showed that these surfactants can improve the dispersion state and Zeta potentials of sol particles and increase the specific surface areas of the precursor powders. Moreover, the precursor powders were composed of MnZn ferrite, and some were amorphous. CTAB was the optimum surfactant and the zeta potential of the sol particles and the specific surface area of the precursor powders named P-0.1CTAB are 10.7 mV and 129.07 m2/g, respectively. In addition, the nano-particles that were made up of the P-0.1CTAB precursor powders had smaller sizes and more uniform particle distributions than the others. The magnetic properties’ improvement was attributed to the addition of surfactants, and CTAB is the optimal type. In addition, the novel nano in situ composite method will inspire fresh thinking and investigation into the research of ferrite.

A novel tactic was employed to evaluate the low-temperature NH3-SCR (selective catalytic reduction) NOx removal property of manganese oxides (MnOx) in various valence states, avoiding the influences of size, morphology and synthetic method on catalytic activity. Firstly, similar sized hollow-spherical MnO2, Mn2O3, Mn3O4 and MnO were obtained by decomposing MnCO3 at 440 and 500 °C in Air, 430 °C in H2 and Ar, respectively. The orders of MnOx catalytic activity varied at different reaction temperature range, while MnO2 showed the best NO conversion. Surface acidity has significant influences on the SCR activity, Mn3O4 exhibits a better catalytic property than Mn2O3 below 300 °C, and conversely, Mn2O3 has a better high-temperature NO conversation than Mn3O4 due to a stronger NH3 adsorption ability above 300 °C. MnO will be oxidized in the studied atmosphere with 5% O2 to Mn3O4, Mn5O8 and finally to Mn2O3 successively, and the mixed phases of MnO/Mn3O4 or Mn3O4/Mn5O8 exhibit a better catalytic activity than Mn2O3 at 200–300 °C. [ABSTRACT FROM AUTHOR]

[Display omitted] • Hollow sphere structure of poly(ionic liquid)s (HPILs) was fabricated as nanoreactor. • HPILs nanoreactor efficiently enhanced the activity of metal catalysts and showed high selectivity of AA. • HPILs could storage and stabilize catalysts during reaction with high activity for 7 times. • HPILs could promote the generation of free radicals to enhance the reaction. • The reaction process of HPILs was theoretically calculated to verify high activity and selectivity. Hollow structure nanoreactors take advantage of catalyst loading and enhanced activity by shell construction. In this work, functionalized poly(ionic liquid)s (PILs) with hollow spherical structures were synthesized by polymerization- and quaternization-based approaches. These hollow structure PILs (HPILs) could be controllable designed from IL monomer easily, giving HPILs various properties. In the subsequent selective oxidation of cyclohexane, the HPILs acting as nanoreactors could efficiently improve the activity of metal salt catalysts (CoCl 2) and displayed adjustable selectivity for cyclohexanone, cyclohexanol (KA) or adipic acid (AA) by different types of HPILs. In kinetic study, it follows first-order reaction kinetics which CoCl 2 /HPIL-C12 had a lower the activation energy of 29.1 kJ/mol. Importantly, these nanoreactors storing the catalysts could be recovered and reused more than 7 times without significant loss of activity. A theoretical model for the hollow spherical reactor was further established to support the advance of the HPILs reactor, which could also help to predict reaction process in other core-shell catalytic system. Due to controlled substrate transfer and enhanced radical generation in HPILs, the reaction process could be adjusted to enhance the conversion of cyclohexane and selective oxidation to AA. [ABSTRACT FROM AUTHOR]

The hydrothermal method was used to synthesize carbon sphere, and the hard template synthesis method was used to prepared C-doped hollow TiO2 sphere (CHTS). Bismuth nitrate was used as bismuth source to modify CHTS. The composite material was oxidized in air atmosphere at 450℃ to obtain Bi2O3 modified C-doped TiO2 hollow spheres(BCHTS). The morphology, elemental composition and photocatalytic degradation efficiency of tetracyclines (TC) by BCHTS hollow spheres were characterized by various measurements. Additionally, the possible transformation pathways and degradation mechanism of tetracycline were revealed via LC–MS and trapping experiments. The experimental results show that the Bi nanoparticles are uniformly dispersed in the CHTS. The photocatalyst exhibits enhanced degradation rate of TC (98.4% under visible-light within 180 min and 99.4% under natural light within 50 min) for its structure and narrow bandgap (2.87 eV). After five degradation cycles, the photocatalyst still remains high removal rate of 96.4% for TC. The results indicate that the photocatalyst may be promising for degrading antibiotic residuals remains. According to the trapping experiment, OH and h+ have a certain role on the photodegradation process, while·O2− is the main active species for degrading TC. [ABSTRACT FROM AUTHOR]

Calcined silica SiO2 hollow spheres (SHS), with a specific surface area of 523 m2 g−1, were used as porous scaffolds of ammonia borane (AB). AB is used as precursor of boron nitride BN. By capillary effect, AB was infiltrated into the porosity of the SHS, and the as-obtained composite AB@SHS was pyrolyzed. Up to 160 °C, AB transforms into polyborazylene (PB); as a result, the composite PB@SHS was produced. Up to 600 °C, BN forms, and the composite BN@SHS was produced. Both composites are porous, with a specific surface area of 360 and 296 m2 g−1 respectively. Results from MAS NMR and XPS analyses showed that PB@SHS and BN@SHS contain B–O bonds, with more B–O bonds and possibly Si–O–B bonds for the latter. In other words, PB@SHS is made of PB, B–O bonds, and SiO2, while BN@SHS is made of BN, B–O bonds, possibly a Si–O–B interface, and SiO2. Based on first attempts, BN@SHS appeared to have a potential for improving the CO2 adsorption properties of the calcined SHS. Expressed in cm3(CO2) g−1, the CO2 uptakes are 6.7 for BN@SHS and 6.3 for the calcined SHS, at 30 °C under 1.5 bar CO2; but expressed in mm3(CO2) m−2, the respective CO2 uptakes are 22.6 and 12. [ABSTRACT FROM AUTHOR]

Dual-gradient drilling technology is being increasingly used in formations with narrow pressure margins. For dual-gradient drilling based on downhole separation, hollow spheres are separated into the annulus at the separator position, resulting in variable mass flow in the wellbore. Thus, existing heat transfer models are no longer suitable for describing wellbore temperature profiles in dual-gradient drilling. This study focused on developing a wellbore heat transfer model that fully considers separated hollow spheres entering the annulus, complex casing programs, and heat sources, for dual-gradient drilling based on downhole separation. The model was solved using an iterative method. Then, the accuracy of the model was verified using temperature data measured from two wells. Finally, the difference in the annular temperature distributions between dual-gradient drilling and conventional single-gradient drilling were investigated, as were the wellbore heat transfer characteristics for dual-gradient drilling. The following major conclusions were drawn: (1) for dual-gradient drilling based on downhole separation, at the separator location, the annular fluid temperature does not decrease, but rather increase in the flow direction because of the inflow of hollow spheres; (2) a clear inflection point exists in the annular fluid temperature curve at the location where the separator would be; (3) the magnitude of the mutation of the temperature curve at the inflection point is considerably affected by the heat capacities of the hollow spheres and the pure drilling fluid; (4) under the same change in separation efficiency, distance between the bit and separator, flow rate, and thermal conductivity of formation, the variation range of the fluid temperature at the bottom hole is greater than that at the wellhead.

In recent years, photocatalytic technology, driven by solar energy, has been extensively investigated to ease energy crisis and environmental pollution. Nevertheless, efficiency and stability of photocatalysts are still unsatisfactory. To address these issues, design of advanced photocatalysts is important. Cadmium sulphide (CdS) nanomaterials are one of the promising photocatalysts. Among them, hollow-structured CdS, featured with enhanced light absorption ability, large surface area, abundant active sites for redox reactions, and reduced diffusion distance of photogenerated carriers, reveals a broad application prospect. Herein, main synthetic strategies and formation mechanism of hollow CdS photocatalysts are summarized. Besides, we comprehensively discuss the current development of hollow-structured CdS nanomaterials in photocatalytic applications, including H2 production, CO2 reduction and pollutant degradation. Finally, brief conclusions and perspectives on the challenges and future directions for hollow CdS photocatalysts are proposed.

Epoxy resin, as a thermosetting polymer material with good performance, has been limited in application due to its high flammability. In this investigation, porous CuO-ZnO hollow spheres (CZHS) were prepared by a hydrothermal method. By incorporation with ionic liquids loaded CuO-ZnO hollow spheres (CZHS@Ils) and ammonium polyphosphate (APP) into epoxy resin (EP) matrix, a new composite flame retardant material, named as EP/7.5APP/1.5CZHS@ILs, was developed for improvement of their thermal insulation and flame retardancy. The thermal conductivity of EP/7.5APP/1.5CZHS@ILs was measured to be 0.0197 W m −1 K −1, which is lesser than that of APP incorporated epoxy resin (EP/APP), demonstrating good thermal insulation capability. The flame retardancy were assessed using the limiting oxygen index (LOI) test, the Vertical flame testing (UL-94) test, and the cone calorimeter (CC) test. The results obtained from LOI test show that the EP/7.5APP/1.5CZHS@ILs has good flame retardancy with a LOI value of up to 28, better than that of pure EP which has a LOI value of 19.2. Moreover, a V-0 level of the EP/7.5APP/1.5CZHS@ILs was observed from the UL-94 test. The peak heat release rate (PHRR) was reduced to 257.9 kW m−2, which is 74.8 % lower than that of the pure EP. Such results are attributed to the synergy effect of CZHS@ILs and APP which offers the epoxy resin excellent flame retardancy. Taking advantages of the excellent thermal insulation, flame retardancy and better mechanical properties, the as-resulted EP/7.5APP/1.5CZHS@ILs may hold great potential for future thermal insulation and flame-retardant applications of energy saving building. [Display omitted] • CuO-ZnO composite hollow spheres were prepared by one-pot hydrothermal synthesis. • CuO-ZnO composite hollow spheres were used as the carrier of ionic liquid. • The prepared EP composite has a LOI value of 28 and its UL-94 reaches V-0 level. • Cone calorimetric test results show that PHRR drop to 257.9 kW m-2, which has excellent flame retardancy. [ABSTRACT FROM AUTHOR]

Introduction. Cylindrical and spherical shells are extensively used in engineering. They face internal and/or external pressure and heat. Stresses and strains distribution in elastoplastic shells has been studied by many scientists. Numerous works involve the use of the von Mises yield conditions, maximum shear stress, maximum reduced stress. These condi- tions do not include the dependence on the first invariant of the stress tensor and the sign of the third invariant of the stress deviator. In some cases, it is possible to obtain numerical-analytical solutions for stresses, displacements and de- formations for bodies with spherical and cylindrical symmetry under axisymmetric thermal and force action.Materials and Methods. The problem on the state of a thick-walled elastoplastic shell is solved within the framework of the theory of small deformations. A plasticity condition is proposed, which takes into account the dependence of the stress tensor on three independent invariants, and also considers the sign of the third invariant of the stress deviator and translational hardening of the material. A disconnected thermoelastoplastic problem is being solved. To estimate the stresses in the region of the elastic state of a spherical shell, an equivalent stress is introduced, which is similar to the selected plasticity function. The construction of the stress vector hodograph is used as a method for verification of the stress state.Results. The problem has an analytical solution for linear plasticity functions. A solution is obtained when the strength- ening of the material is taken into account. Analytical and graphical relationships between the parameters of external action for the elastic or elastoplastic states of the sphere are determined. For a combined load, variants are possible when the plastic region is generated at the inner and outer boundaries of the sphere or between these boundaries.Discussion and Conclusions. The calculation results have shown that taking into account the plastic compressibility and the dependence of the plastic limit on temperature can have a significant impact on the stress and strain state of a hollow sphere. In this case, taking into account the first invariant of the stress tensor under the plasticity condition leads to the fact that not only the pressure drop between the outer and inner boundaries of the spherical shell, but the pressure values at these boundaries, can vary within a limited range. In this formulation of the problem, when there is only thermal action, the hollow sphere does not completely pass into the plastic state. The research results provide predicting the behavior of an object (a hollow sphere) that experiences centrally symmetric distributed power and thermal external influences.

Surface-Enhanced Raman Spectroscopy attracts great interests for its ability to detect a variety of molecules at trace level. However, the commonly used noble metal substrates suffer from high cost, poor biocompatibility and inferior stability. Some oxides have the potential to substitute for noble metal and much effort has been made to improve their performance. In this paper, MoO2 nanocones were prepared and self-assembled into hollow spheres. The structure exhibits an enhancement factor (EF) of 3 × 107 and a limit of detection (LOD) of 10−9 M for Rhodamine 6G (R6G). This performance is among the best of all the oxides and is comparable to that of Au and Ag. The morphology control of hollow MoO2 sphere was also discussed.

The as-prepared C@SnO 2 material displayed dual hollow sphere structure, and the void inside sphere can serve as buffer space for volume expansion. Due to hollow structure and carbon coating, such the C@SnO 2 anode delivered a reversible capacity of 925 mAh/g after 500 cycles, much higher than 506 mAh/g of pristine SnO 2. [Display omitted] • Material displayed distinctive dual hollow sphere structure. • Void inside sphere can buffer volume expansion during lithiation. • C@SnO 2 presented high initial Coulomb efficiency of 85%. • C@SnO 2 delivered reversible capacity of 925 mAh/g after 500 cycles. As high capacity anode material, tin dioxide has a bottleneck of poor cycling performance. In this study, dual hollow sphere C@SnO 2 material was synthesized by hydrothermal method plus calcination process. The diameter of single hollow sphere was 800 − 1000 nm, and the void inside sphere can serve as buffer space for volume expansion. During electrochemical testing, the C@SnO 2 anode delivered high initial Coulomb efficiency of 85 % and reversible capacity of 925 mAh/g at 0.2C after 500 cycles. It indicates that this work develops an available strategy to prepare high-performance anode material of lithium-ion batteries. [ABSTRACT FROM AUTHOR]

• The as-prepared Ni 2 P has a single-crystal. • Ni 2 P shows a special uniform hollow spherical structure. • Crystal structure and morphology of Ni 2 P can be controlled by the surfactants. • The as-prepared Ni 2 P exhibits excellent adsorption activity. The single-crystal Ni 2 P hollow spheres have been synthesized via a solvothermal route in presence of mixed surfactant. It is showed that solvent played a significant role for the synthesis of Ni 2 P. Furthermore, the structure of hollow spheres would be obtained only using the mixtures of cetyltrimethyl ammonium bromide (CTAB) and sodium dodecyl benzene sulfonate (SDBS) which act as soft template rather than single CTAB or pure SDBS. Finally, it turned out that the single-crystal Ni 2 P hollow spheres exhibit excellent adsorption activity for malachite green (MG) organic dyes. [ABSTRACT FROM AUTHOR]

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Within the framework of the theory of thermoelasticity, the problem of the generation of additional internal thermal stresses in a composite material with granular fillers under the influence of temperature is posed. Using the spherical inclusion model applied in the theory of composites, constitutive equations are formulated, and their analytical closed-form solutions are constructed. It is shown that the internal thermal stresses initiated in the system have a localized character, are proportional to the values of the elastic moduli of the materials of each phase and the difference between their coefficients of linear thermal expansion, and decrease in inverse proportion to the cube of the radial coordinate. With the help of specific applied examples, it has been established that even at relatively moderate values of temperature changes, these stresses can reach limit values that contribute to the initiation of internal latent localized defects and cracks in the system. The cases of thermally stressed states of a spherical inclusion coated with a layer of another material, an inclusion with a cavity, and a spherical pore are also considered. [ABSTRACT FROM AUTHOR]

Copper‐ceria has been widely investigated as an active heterogeneous catalyst for CO oxidation reaction. Herein we report a reliable synthesis of CuO loaded ceria hollow spheres (CHS‐CuO) which show an outstanding performance of 6.1712 μmolCO⋅gcat−1⋅s−1 CO consumption rate at 120 °C over other reported ceria‐based catalysts for the CO oxidation reaction. The performance is superior to CuO loaded ceria nanoparticles (CNP‐CuO) and ceria hollow spheres (CHS), due to hollow structure, large surface area, more adsorptive oxygen and subsequent lower activation energy. TEM images reveal CuO nanoparticles are uniformly dispersed on the surface of ceria hollow spheres. XPS investigation shows that Cu2+ is the dominant copper species in CHS‐CuO. The synthesis reliability is demonstrated with the case of Ag loaded CHS fabrication. The reported strategy enables the fabrication of similar bimetal hollow spheres, holding good promise for various heterogeneous catalysis. [ABSTRACT FROM AUTHOR]

The facile design and fabrication of nanoarchitectured binary transition metal oxide electrode materials are essentially required for the advancement of highperformance supercapacitors (SCs). Herein, we prepared an oxygen-vacant NiMoO4 (Ov-NiMoO4) hollow sphere via a simple hydrothermal approach and subsequent heat treatment under an argon atmosphere. In particular, the oxygen vacancy is confirmed by using X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), Raman, and differential reflectance spectroscopy (DRS) UV-Vis spectra studies. Furthermore, the generation of the oxygen vacancy could enhance the electrical conductivity and improve Faradaic redox sites. Significantly, the Ov- NiMoO4 hollow sphere depicts a larger specific capacity (Csp) of 496 mA h g-1 at 1 A g-1than the bare-NiMoO4 (b-NiMoO4; 279 mA h g-1) thermally treated under air. Furthermore, the hybrid SC (HSC) is fabricated based on the Ov- NiMoO4//activated carbon, revealing a high specific capacitance (Cs) of 120 F g-1 and providing a large energy density (ED) of 37.49 W h kg-1 and power density (PD) of 36.61 kW kg-1. Moreover, the HSC shows considerable cyclic stability of ~91.14% over 20 000 cycles. The results divulge that the poor crystallinity and the introduction of oxygen vacancies play a vital role in enhancing the charge-storage capability of the materials. [ABSTRACT FROM AUTHOR]

Hollow spheres of nickel oxide (NiO) and silver, gold, and platinum nanoparticle loaded NiO composites were successfully produced by using polystyrene (PS) latexes as hard template. Due to the presence of tertiary amine based diblock copolymer stabilizer on the surface of PS, the tertiary amine functional groups provided homogene deposition of nickel hydroxide, and then the precursor NiO salt production on the surface of PS latexes with a controlled precipitation technique. Then, NiO and NiO/metal NP hollow spheres were produced by calcination at 600 °C. Thermogravimetric analysis indicated that the amounts of NiO and NiO‐composite after calcination were in the range of 21.1–29.7 wt%. The diameters of metal oxide spheres were in the range of 2.0–2.7 μm and the shell thickness were in the range of 250–350 nm. These structures had very low densities due to their porous and hollow structures and had outer layers with highly rough surfaces due to formation of nanosheets, which may offer important advantages for catalysis studies. [ABSTRACT FROM AUTHOR]