Uniform Shell Research Articles

Annular acoustic black holes to reduce sound radiation from cylindrical shells

Annular acoustic black holes (ABHs) have been recently proposed as a potential means for reducing vibrations of cylindrical shells. The latter are very common structures in the naval, aeronautic and industrial sectors so widening ABH applications from flat plates to curved structures seems worth exploring. This work focuses on the benefits of embedding annular ABH indentations on cylindrical shells to reduce outward sound radiation. The goal of the paper is to propose a semi-analytical method to determine the acoustic power, radiation efficiency, source location and far-field acoustic pressure of ABH shells and compare them with those of uniform thickness shells. The vibration field of the ABH and uniform cylindrical shells is computed by means of the Gaussian expansion method (GEM) within the Rayleigh–Ritz approach. Then, the radiated pressure is obtained by solving the Helmholtz equation in cylindrical coordinates using the Green’s function method. The surface of the cylinder is discretized into small finite size radiators and an impedance matrix is used to obtain the acoustic surface pressure in terms of the shell radial velocity. To determine those regions of the cylinder responsible for the far field radiated sound, use is made of supersonic sound intensity (SSI). A method is proposed to calculate the SSI in the spatial domain for cylindrical shell structures which allows one to make direct use of the previously computed surface pressure and velocity distributions. The whole methodology is validated against finite element method (FEM) simulations and after that, results are presented for an acoustically thick shell. The roles played by the critical and ring frequencies are reported and the spectra of the acoustic power, radiation efficiency and far field acoustic pressure get analysed. It is shown that the annular ABH can become very effective when the cylinder flexural motion dominates over the circumferential one. The slow down of bending waves inside the ABH makes structural supersonic waves (in relation to sound speed) become subsonic at some point, which clearly diminishes the shell radiation efficiency. Overall, it is described why embedding an annular ABH on a cylindrical shell can strongly help reducing the radiated sound to the far-field.

The effect of activation pretreatment on the morphology of Ag microsphere and the microwave absorption performances of Ag@MWCNTs hybrids

The silver microspheres with controllable morphology and structure were prepared by electroless plating with activated PS microspheres as template, which were used to construct a 3D absorbing hybrids of [email protected] The SEM and EDS results illustrated that a uniform silver shell was coated on the surface of PS microsphere because of the activation, which was conductive to construct an excellent conductive network to attenuate electromagnetic wave. Meanwhile, the plating solution concentration had an important effect on the morphology of Ag microsphere and microwave absorption performances of the absorbing hybrids. When the concentration was 12 g/L, the silver shell of B-2 microsphere was uniform and dense. However, lower or higher concentration were unfavorable to the integrity of Ag shell of B-1 and B-3 microsphere. For the [email protected] absorbent hybrids, the reflection loss value was −37.00 dB at 9.9 GHz, while that of [email protected] and [email protected] hybrids were −27.35 dB at 8.5 GHz and −24.07 dB at 11.3 GHz, respectively. All the results indicated that the controlling measures of activation for PS microspheres and proper plating solution concentration are crucial to enhance the microwave absorbing performances of absorbing hybrids.

Temperature-induced microstructural changes in shells of laboratory-grown Arctica islandica (Bivalvia).

Bivalve shells are increasingly used as archives for high-resolution paleoclimate analyses. However, there is still an urgent need for quantitative temperature proxies that work without knowledge of the water chemistry–as is required for δ18O-based paleothermometry–and can better withstand diagenetic overprint. Recently, microstructural properties have been identified as a potential candidate fulfilling these requirements. So far, only few different microstructure categories (nacreous, prismatic and crossed-lamellar) of some short-lived species have been studied in detail, and in all such studies, the size and/or shape of individual biomineral units was found to increase with water temperature. Here, we explore whether the same applies to properties of the crossed-acicular microstructure in the hinge plate of Arctica islandica, the microstructurally most uniform shell portion in this species. In order to focus solely on the effect of temperature on microstructural properties, this study uses bivalves that grew their shells under controlled temperature conditions (1, 3, 6, 9, 12 and 15°C) in the laboratory. With increasing temperature, the size of the largest individual biomineral units and the relative proportion of shell occupied by the crystalline phase increased. The size of the largest pores, a specific microstructural feature of A. islandica, whose potential role in biomineralization is discussed here, increased exponentially with culturing temperature. This study employs scanning electron microscopy in combination with automated image processing software, including an innovative machine learning–based image segmentation method. The new method greatly facilitates the recognition of microstructural entities and enables a faster and more reliable microstructural analysis than previously used techniques. Results of this study establish the new microstructural temperature proxy in the crossed-acicular microstructures of A. islandica and point to an overarching control mechanism of temperature on the micrometer-scale architecture of bivalve shells across species boundaries.

Synthesis of Core@Shell Cu-Ni@Pt-Cu Nano-Octahedra and Their Improved MOR Activity.

Fabrication of 3d metal-based core@shell nanocatalysts with engineered Pt-surfaces provides an effective approach for improving the catalytic performance. The challenges in such preparation include shape control of the 3d metallic cores and thickness control of the Pt-based shells. Herein, we report a colloidal seed-mediated method to prepare octahedral CuNi@Pt-Cu core@shell nanocrystals using CuNi octahedral cores as the template. By precisely controlling the synthesis conditions including the deposition rate and diffusion rate of the shell-formation through tuning the capping ligand, reaction temperature, and heating rate, uniform Pt-based shells can be achieved with a thickness of <1 nm. The resultant carbon-supported CuNi@Pt-Cu core@shell nano-octahedra showed superior activity in electrochemical methanol oxidation reaction (MOR) compared with the commercial Pt/C catalysts and carbon-supported CuNi@Pt-Cu nano-polyhedron counterparts.

Flow Microreactor Synthesis of Zeolitic Imidazolate Framework (ZIF)@ZIF Core-Shell Metal-Organic Framework Particles and Their Adsorption Properties.

Metal-organic frameworks (MOFs) with core-shell structures enable to enhance intrinsic properties of constituent MOFs and impart additional functional activities. Although shell thickness is a key factor for regulating the properties of core-shell MOF particles, controlling it has been challenging. The widely used batch reactor synthesis cannot produce core-shell particles with uniform shell thickness because of poor reactant mixing. A microreactor could ensure excellent mixing, and that would allow to control shell thickness. In this study, we synthesized zeolitic imidazolate framework-8 (ZIF-8)@ZIF-67 and ZIF-67@ZIF-8 core-shell particles using a microreactor and investigated the effects of the mixing performance on the shell thickness of the obtained particles. Our results demonstrated that rapid mixing was critical for the uniformity of the synthesized particles. The concentration of core particles is another key factor that can preferentially induce heterogeneous nucleation on the surface of the core particles without inducing self-nucleation in the bulk solution, particularly when the self-nucleation rate of the shell MOF is high. The N2 adsorption isotherms of the synthesized particles revealed their unique adsorption properties, which were ascribed to the core-shell structures obtained at low shell formation rates. Our simple and versatile synthesis technique not only allowed the preparation of ZIF@ZIF particles with novel functionalities but also can be extended to synthesize core-shell MOF particles with different combinations of core particles and shells.

Dual-Protected Metal Halide Perovskite Nanosheets with an Enhanced Set of Stabilities.

Approaches to achieve stable perovskite nanocrystals (PNCs) of interest, in particular those with large structural anisotropy, through protective coating of the inorganic shell at a single-nanocrystal (NC) level are comparatively few and limited in scope. Reported here is a robust amphiphilic-diblock-copolymer-enabled strategy for crafting highly-stable anisotropic CsPbBr3 nanosheets (NSs) by in situ formation of a uniform inorganic shell (1st shielding) that is intimately ligated with hydrophobic polymers (2nd shielding). The dual-protected NSs display an array of remarkable stabilities (i.e., thermal, photostability, moisture, polar solvent, aliphatic amine, etc.) and find application in white-light-emitting diodes. In principle, by anchoring other multidentate amphiphilic polymer ligands on the surface of PNCs, followed by templated-growth of shell materials of interest, a rich variety of dual-shelled, multifunctional PNCs with markedly improved stabilities can be created for use in optics, optoelectronics, and sensory devices.

Three dimensional confined states in core-shell diameter modulated nanowires

Three-dimensional confined states in a GaP nanowire which partially covered by a uniform InP shell have been investigated in this paper. To this end, based on the effective mass approximation and by using the finite element method electronic energy states of the system were calculated. To attain physical insight on the numerical results, we have utilized the concept of one dimensional angular momentum dependent effective potential. Our results indicate a peculiar effect of increasing the 3D confinement of electrons in the shell which partially covered the nanowire by increasing the angular momentum. Surviving the effective potential declares that this effect arises as a consequence of contact with the semi-infinite nanowire parts of the system and, as a result, leads the bound states of higher angular momentum to lie in the energy continuum of the lower ones. On the other hand, application of external magnetic field reduces the number of 3D confined states in the core–shell region. Analysis of the reverse structure, i.e. InP nanowire which partially covered with GaP, indicates a significant increase in electronic confinement in the core–shell section with respect to the InP/GaP counterpart as a result of lower electronic effective mass of InP regarding to GaP.

Dual‐Protected Metal Halide Perovskite Nanosheets with an Enhanced Set of Stabilities

AbstractApproaches to achieve stable perovskite nanocrystals (PNCs) of interest, in particular those with large structural anisotropy, through protective coating of the inorganic shell at a single‐nanocrystal (NC) level are comparatively few and limited in scope. Reported here is a robust amphiphilic‐diblock‐copolymer‐enabled strategy for crafting highly‐stable anisotropic CsPbBr3 nanosheets (NSs) by in situ formation of a uniform inorganic shell (1st shielding) that is intimately ligated with hydrophobic polymers (2nd shielding). The dual‐protected NSs display an array of remarkable stabilities (i.e., thermal, photostability, moisture, polar solvent, aliphatic amine, etc.) and find application in white‐light‐emitting diodes. In principle, by anchoring other multidentate amphiphilic polymer ligands on the surface of PNCs, followed by templated‐growth of shell materials of interest, a rich variety of dual‐shelled, multifunctional PNCs with markedly improved stabilities can be created for use in optics, optoelectronics, and sensory devices.

Exceptionally redox-active precursors in the synthesis of gold core-tin oxide shell nanostructures

Core-shell nanostructures are important for applications in sensors, electronics, and fuel cells. We report the synthesis of AuNPs-aryl shell@SnO2 core-shell nanostructure (Au@SnO2) in one-step by green and direct reaction of the redox couples of SnCl22H2O with aryldiazonium gold(III) salt [HOOC-4-C6H4-N≡N]AuCl4 in aqueous solution. The spontaneous reaction occurred simultaneously at room temperature to form a markedly stable structure of Au@SnO2, in which the gold core surface is functionalized with carboxyl groups of -C6H4COOH. The reaction is facilitated by the low reduction potential of diazonium gold salt (aryl/aryl and Au3+/Au°) and the facile oxidation of tin (Sn2+/Sn4+). From the overall analysis, the presence of the organic shell boosted tailoring the gold core with immobilized, full coverage, and uniform shell of SnO2 Lewis acid. XPS results provided strong supporting evidence for gold in the metallic state and tin in the oxidized state as SnO2 compound. From TEM measurements, the average size of AuNPs increased from 10.4 ± 4.2 nm to 50.4 ± 17.9 nm when treated at higher temperatures (i.e., room temperature, 300 °C, and 800 °C). The average size of SnO2 also increased from 3.0 ± 0.6 nm to 48.9 ± 15.8 nm as the heat-treatment temperature increased, besides, the coverage by SnO2 decreased due to an increment of particle sizes of both AuNPs and SnO2. At 800 °C, it was difficult to see the core-shell structure. The redox route not only revisits the making of Purple of Cassius but can also be universal and extended to substantial Au@MxOy core-shell structures for catalysis and gas sensors.

Mechanical properties, microstructure and crack healing ability of Al2O3/TiC/TiB2/h-BN@Al2O3 self-lubricating ceramic tool material

To prepare a self-lubricating ceramic tool with excellent mechanical properties and crack healing ability, the h-BN@Al2O3 solid lubricant with a core-shell structure was prepared by the heterogeneous nucleation method, and was added into Al2O3/TiC ceramic matrix together with TiB2. Examination of the micro-morphology and phase composition of h-BN@Al2O3 found that the surface of the solid lubricant h-BN was coated with Al(OH)3 at first, and after calcination at 1200 °C, a dense and uniform Al2O3 shell was formed. At the same time, the effects of the h-BN@Al2O3 addition on the ceramic tool material were studied. The mechanical properties of the ceramic tool material with h-BN@Al2O3 were improved relative to than those with h-BN. The optimal content of h-BN@Al2O3 solid lubricant was 5 vol%. In the friction and wear test, h-BN in h-BN@Al2O3 particles can be stripped to form a solid lubricating film on the material surface, which plays a good role in reducing wear and resisting wear. The crack healing ability of the self-lubricating ceramic tool material was studied by prefabricating cracks with a length of 400 μm on the surface. After a heat treatment at 700 °C for 60 min, the surface cracks of the ceramic tool material were completely healed, and the flexural strength was restored to 90% of that of the smooth samples. The oxidation of TiB2 and h-BN in ceramic tool materials is the main reason for crack healing.

Polyaniline-coated core-shell silica microspheres-based dispersive-solid phase extraction for detection of benzophenone-type UV filters in environmental water samples

Polyaniline-modified core-shell mesoporous silica (CSMS@PANI) nanocomposite microspheres are synthesized as adsorbent in dispersion-solid phase extraction (d-SPE) for enrichment and purification of benzophenone-type UV filters. The synthesized CSMS@PANI nanocomposite microspheres exhibit large specific surface area (33.45 m2/g) and uniform fibrous shell (microsphere diameter of 1.3 μm, outer silica shell thickness of 120 nm, pore diameter of 12.04 nm), which can greatly improve the extraction efficiency of the samples. Combining CSMS@PANI based d-SPE with sheathless capillary electrophoresis-tandem mass spectrometry for detection, we can achieve sensitive determination of six benzophenone-type UV filters with the detection limit of 0.6 pg/mL-0.2 ng/mL and the enrichment factors of 470-660. The method is successfully applied for ultrasensitive detection of trace amount benzophenone-type UV filters in environment water samples. It is indicated that the method has the advantages of rapid and efficient enrichment, high sensitivity, and excellent repeatability. Our study extends the application of core-shell mesoporous silica materials and would be of value for pretreatment of trace-amount and complex real samples.

High coercivity Nd-Fe-B magnet with low Tb concentration by combined diffusion

Commercial N50 Nd-Fe-B magnet was processed by a combined diffusion process with Pr65Cu15Al20, followed with Pr50Tb30Al20 (at %). The coercivity increment from the original 965.6 kA/m to 1672.5 kA/m was achieved in the combined diffusion sample by introducing 0.23 wt% Tb. However, the coercivity of the conventionally diffused sample with similar Tb content by Pr50Tb30Al20 reached only 1386.2 kA/m. Microstructural and compositional analyses revealed that relatively continuous grain boundary phases were first formed in the diffused sample by Pr65Cu15Al20, moreover, appropriate Tb-rich shells around 2:14:1 grains were further formed during the following diffusion by Pr50Tb30Al20 alloy. The combined diffusion process was helpful in promoting Tb diffusing along the grain boundary phase and further forming uniform Tb-rich shells. It provided a promising way of accelerating Tb diffusing and enhancing Tb availability.

A method for the growth of uniform silica shells on different size and morphology upconversion nanoparticles.

Lanthanide-doped upconversion nanoparticles have emerged as attractive candidates for biomedical applications. This is due to their excitation and emission wavelengths, which lay the foundation for deeper penetration depth into biological tissue, higher resolution due to reduced scattering and improved imaging contrast as a result of a decrease in autofluorescence background. Usually, their encapsulation within a biocompatible silica shell is a requirement for their dispersion within complex media or for further functionalization of the upconversion nanoparticle surface. However, the creation of a silica shell around upconversion nanoparticles can be often challenging, many times resulting in partial silica coating or nanoparticle aggregation, as well as the production of a large number of silica particles as a side product. In this work we demonstrate a method to accurately predict the experimental conditions required to form a high yield of silica-coated upconversion nanoparticles, regardless of their shape and size.

Two-photon polymerization printed lattices as support structures in multi-shell ICF targets: Platform development and initial assessment

Recent interest in fielding direct drive multi-shell targets on the NIF [K. Molvig et al., Phys. Rev. Lett. 116, 255003 (2016) and S. X. Hu et al., Phys. Rev. E 100, 063204 (2019)] has highlighted the need for a low density structure to support the inner shell(s) and to avoid energy loss in the acceleration and collision process. We have developed a two-shell platform to evaluate the use of low density two-photon polymerization (2PP) printed lattices as a support structure between the shells. 2PP structures are an attractive option because they can be produced at densities as low as 5 mg/cc, which is ideal for multi-shell targets, and their 3D structure can be tailored to the user's needs. However, idealized 1D simulations of lattice strut surrogate thin shells indicate that the lattice will only isotropize before the shells collide if the strut thickness is sufficiently fine. This platform makes use of high resolution Fresnel zone plate images to evaluate the uniformity of the post-collision inner shell and provide information on how efficiently the lattice structure isotropizes. As a proof of principle, an initial experiment contrasts the case of 5 μm lattice struts that cause significant disfiguration of the inner shell with the uniform post-collision inner shell in the absence of this material. Finer lattice structures on future experiments will evaluate post-collision inner shell uniformity. This new platform and accompanying diagnostic technique can also be used to evaluate both asymmetry in capsule drive and target non-uniformities with resolution up to mode 40.

Remote set of oyster (Crassostrea virginica) in various aquaculture gear

Remote-setting of oyster, Crassostrea virginica, larvae from the disease-resistant Haskin NEH line is performed every other year in Delaware to supply small-scale oyster enhancement efforts, citizen oyster gardening program. Over the past four remote sets (2009, 2011, 2013, 2015), three types of shell containment gear were utilized to monitor and compare the setting efficiency rate and post-set survival. Shell containment gears included diamond, plastic mesh bags (2009, 2011), wire baskets (2011, 2015), and plastic aquaculture trays (2013, 2015). Average setting efficiency was estimated at 28%, 23%, 17%, and 29% in the respective 2009, 2011, 2013, and 2015 remote sets while gear specific settling efficiency (%) include 28% for mesh bags in 2009, 22% for mesh bags and 33% for wire baskets in 2011, 17% for aquaculture trays in 2013, and 30% for aquaculture trays and 22% for wire baskets in 2015. Settling efficiency was lowest in 2013 using aquaculture trays compared to other years while aquaculture trays in 2015 and wire baskets in 2011 resulted equally higher settling efficiency. For small-scale growers, the stacked aquaculture trays are advantageous for several reasons: reducing handling time, uniform shell distribution within tanks, environmentally friendly alternative, and ease of cleaning detritus between shell layers.

A surface-engineering-assisted method to synthesize recycled silicon-based anodes with a uniform carbon shell-protective layer for lithium-ion batteries

Yolk-shell silicon/carbon composite encapsulated by uniform carbon shell (Si@C) are becoming an effective method to mitigate volume-related issues of Si-based anodes and maintain an excellent performance for lithium-ion batteries (LIBs). However, a uniform carbon shell in Si@C is difficult to guarantee. Herein, a facile surface-engineering-assisted strategy is described to prepare Si@C composite with low-cost modified recycled waste silicon powders (RWSi) as core coated by a uniform carbon shell-protective layer derived from the pyrolysis of poly (methyl methacrylate) (PMMA) as carbon source (m-RWSi@PMMA-C). In this process, surface-engineering is performed with silane coupling agent kh550 to functionalize the RWSi particles via a silanization reaction, guaranteeing a uniform PMMA coating which will be transformed into carbon shell-protective layer after carbonization. The m-RWSi@PMMA-C electrode delivers an optimal discharge capacity of 1083 mAhg−1 at 200 mAg−1 after 200 cycles with an initial capacity of 3176.2 mAhg−1 and a high initial Coulombic efficiency (ICE) of 75.6%. Based on these results, the recycled silicon-based anode with a uniform carbon shell-protective layer displays great application potential and it also brings a new perspective on silicon-based anodes via surface-engineering method for LIBs.

Intermetallic Co-Pt/C Nanoparticles Synthesized Via Sonochemical Method As Enhanced Electrocatalysts for Cathode of PEMFC

For fuel cell stack of 80 kW, platinum for electrocatalyst requires around 10 g per fuel cell electric vehicle (FCEV). A large-scale synthesis method for the low-platinum catalyst is necessary for this field to reduce man-power. Ultrasound-assisted polyol synthesis (UPS) is a method for the preparation of small and uniform size transition metal core-platinum shell nanoparticles evenly distributed on the support. Platinum(Ⅱ) acetylacetonate, Cobalt(Ⅱ) acetylacetonate, and carbon support were dispersed in ethylene glycol which is reducing agent and irradiated by ultrasound for 3 h to reduce the precursor to metal nanoparticles, followed by washing and drying to obtain a powder. The characterization was observed by solution color visualization, X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), inductively coupled plasma atomic emission spectroscopy (ICP-AES) and electrocatalytic performance. Also, the synthesized samples were calcined at various temperatures to cause the atomic rearrangement to the most stable arrangement, and atomic accumulation of boundary between each atom and compression of platinum lattice that affects activity or durability of electrocatalyst has changed. Synthesized sample with optimized synthesis and treatment condition shows improved electrochemically active surface area (ECSA) and Oxygen reduction reaction (ORR) catalytic activity in the half-cell test and durable catalytic activity in the performance evaluation of membrane-electrode assembly (MEA) compared to existing Platinum catalyst. As renewable energy conversion and storage system is one of the main challenges, FCEV is developed to solve pollution from CO2 emission and oil depletion issues. Our low-platinum nanoparticle with uniform distribution synthesized using a sonochemical method will replace precious metal catalysts used in fuel cells instead of platinum catalysts.

Over All Water Splitting By Anti-Photocorrosive Core-Shell Composite Sulfide Photocatalyst Synthesized Via Acid Dissolution Process

Some of the most significant challenges of the 21st century are related to energy exhaustion and global warming. In order to overcome these issues, it is necessary to produce sustainable energy without carbon dioxide emissions. Since the discovery of the Honda-Fujishima effect (H2O + 2h ν → 1/2 O2 + H2) in 1972, photocatalytic water splitting has attracted considerable attention as a solution to energy exhaustion. Since hydrogen is a clean source of energy that does not generate carbon dioxide when employed, water splitting has been considered an effective measure against global warming. The most commonly studied photocatalyst is TiO2. However, hydrogen production from water using TiO2 requires ultraviolet light, which deems it inefficient. In order to achieve a high conversion efficiency, which is considered suitable for practical applications, it is necessary to achieve a minimal absorption of visible light. To satisfy this requirement, a visible-light-responsive photocatalyst should be employed in the water splitting process. However, many of the photocatalysts with high visible light responsiveness, such as sulfide semiconductors and nitride semiconductors, have photocorrosive issues. This is an issue where hole carriers generated by photo-excitation cause the oxidative decomposition of the photocatalyst itself. To date, two approaches have been reported to suppress photocorrosion. The first is to transfer photocorrosive holes to different photocatalysts. The transfer of holes to the valence band of another photocatalyst has been reported. (H. Nagakawa et al., ACS Omega, 2018, 3, 10, 12770-12777.) In the previous study, the hydrogen generation efficiency was increased by transporting the excited electrons and holes from CdS to SiC. This approach successfully suppressed the photocorrosion of CdS. The second photocorrosion suppression method is to protect the photocorrosion-susceptible photocatalyst with different stable photocatalysts, thereby reducing exposure to the solution and preventing elution. The current authors reported that this method promoted the water splitting reaction in a CdS composite photocatalyst. (H. Nagakawa et al., ACS Applied Energy Materials, 2018, 1, 12, 6730-6735.) In the study, we achieved an overall water splitting under visible light using a home-synthesized tri-composite, in which CdS was covered with a photocatalyst on both the oxidation and reduction sides. Previously, the use of CdS/SiC/TiO2 tri-composite photocatalysts was found to promote the consumption of holes on CdS and reduce the exposure of CdS to the solution, thereby suppressing photocorrosion. However, since oxidation of water cannot be achieved with the oxidizing power of SiC, in this study, we employed WO3 instead of SiC and realized stronger oxidizing power by constructing a Z-scheme. In addition, we employed CdWO4 as a photocatalyst on the reduction side in order to enable the transport of electrons excited on CdS to the conduction band of CdWO4. A highly controlled CdS/CdWO4 core–shell composite was synthesized by a simple method via the dissolution of CdS under acidic conditions. The eluted Cd2+ reacted with the dissolved WO4 2- in solution in situ, allowing selective deposition on the CdS surface for uniform shell synthesis. (H. Nagakawa et al., RSC Advances, 2020, 10, 1, 105-111.) As a result, recombination was suppressed and the hydrogen production ability was improved compared to that of the dispersion system of CdS and WO3. Furthermore, water splitting was achieved by reducing the CdS exposure and suppressing photocorrosion. Hydrogen evolution experiments were conducted in vial bottles under Ar flow. First, 1 wt % Pt was deposited on the prepared photocatalyst using H2PtCl6·6H2O through photo-deposition under visible light (λ > 420 nm) in 30 vol% methanol aqueous solution. The synthesized CdS/WO3/CdWO4-Pt composite photocatalyst (0.03 g) and pure water (15 mL) were prepared in the reaction cell. A Xe lamp with a UV cutoff filter (λ > 420 nm) was used as a visible-light source. A 0.1 mL aliquot of the evolved gas was collected using a gastight syringe, and the sampled gas was injected into the gas chromatograph to determine the amounts of evolved hydrogen and oxygen. As a result, hydrogen and oxygen were constantly produced at a ratio of 2 : 1 while suppressing photocorrosion. This is the first report of water splitting by a powder-based photocatalyst using CdS under visible light. Figure 1

Pd coated one-dimensional Ag nanostructures: Controllable architecture and their electrocatalytic performance for ethanol oxidation in alkaline media

One-dimensional (1D) metal-coated Pd structures are efficient catalysts for the ethanol electro-oxidation and promising strategy for minimizing the Pd-loading toward commercialization of direct ethanol fuel cells (DEFCs). Herein, the decorated and core-shell architectures of a novel Pd coating on Ag nanowires (PdAg-NWs) are controllable by a two-step polyol method based on the galvanic replacement reaction. The integration of uniform shell with a low Pd concentration and partial hollow structure onto 1D PdAg-NWs exhibits the highest efficiency for ethanol oxidation reaction (EOR) in alkaline solution. In comparison with Pd nanoparticles (PdNPs/C), the PdAgNWs/C performes 11 times superior EOR activity, and the onset potential shifts 80 mV negatively. The presence of Ag in PdAg-NWs enhances the absorption capacity of ethanol molecules and hydroxyl ions on the active sites, and improves the catalyst tolerance to CO-like intermediates, making them a potential anodic catalyst for DEFCs.

Space-confined synthesis of nitrilotriacetic acid immobilized magnetic sorbents in aqueous continuous phase of high internal phase emulsion for removing bivalent cadmium

• Space-confined synthesis of NAIMSs-E in aqueous continuous phase of HIPEs is conducted. • High quality sorbents are applied for removing Cd 2+ from aqueous solutions. • DA-NTA moieties not only endow abundant binding sites, but also act as robust anchor. • NAIMSs-E possess sensitive response under magnetic field, fast uptake and large adsorption amount. Monodispersed magnetic sorbents (MMSs) display great potential for adsorptive removal of pollutants, but the conventional methods cannot meet requirements of scalable, time-saving, and energy-efficient fabrication. In this work, space-confined synthesis of nitrilotriacetic acid immobilized magnetic sorbents (NAIMSs-E) in aqueous continuous phase of high internal phase emulsions (HIPEs) was conducted, and as-prepared high quality sorbents (sensitive response to magnetic field, abundant affinity groups, uniform shell size, and stable structure) were applied for removing bivalent cadmium (Cd 2+ ) from aqueous solutions. 2-(Bis-carboxymethyl-amino)-6-{3-[2-(3,4-dihydroxy-phenyl)-ethylcarbamoyl]-propionylamino}-hexanoic acid was firstly synthesized as a robust anchor and a functional modifier onto magnetic Fe 3 O 4 . The effects of synthesis conditions to the morphology and structure were studied, and the forming mechanism based on emulsion nano-reactor was demonstrated. NAIMSs-E are expected to possess fast equilibrium rate, and approximately 90% of the maximum adsorption capacity is achieved within 60 min. The maximum uptake amounts are 49.98 mg g −1 , 80.58 mg g −1 , 176.4 mg g −1 at 288 K, 298 K, and 308 K, respectively, and the monolayer chemisorption based on sharing and transferring of electrons is the main rate-limiting step. Moreover, NAIMSs-E have excellent regeneration and specific affinity towards Cd 2+ , even for actual water samples. In addition, the spontaneous, endothermic, and entropy increased adsorption process is also confirmed. Therefore, this work not only presents a new clue to fabricate MMSs via simple emulsion nano-reactor, but also provides a novel platform for Cd 2+ removal.