Original Fuel‐Cell Membranes from Crosslinked Terpolymers via a “Sol–gel” Strategy

Hybrid organic/inorganic membranes that include a functionalized (‐SO₃H), interconnected silica network, a non‐porogenic organic matrix, and a ‐SO₃H‐functionalized terpolymer are synthesized through a sol–gel‐based strategy. The use of a novel crosslinkable poly(vinylidene fluoride‐ter‐perfluoro(4‐methyl‐3,6‐dioxaoct‐7‐ene sulfonyl fluoride)‐ter‐vinyltriethoxysilane) (poly(VDF‐ter‐PFSVE‐ter‐VTEOS)) terpolymer allows a multiple tuning of the different interfaces to produce original hybrid membranes with improved properties. The synthesized terpolymer and the composite membranes are characterized, and the proton conductivity of a hybrid membrane in the absence of the terpolymer is promising, since 8 mS cm^?1 is reached at room temperature, immersed in water, with an experimental ion‐exchange‐capacity (IEC_exp) value of 0.4 meq g^?1. Furthermore, when the composite membranes contain the interfaced terpolymer, they exhibit both a higher proton conductivity (43 mS cm^?1 at 65 °C under 100% relative humidity) and better stability than the standard hybrid membrane, arising from the occurrence of a better interface between the inorganic silica and the poly[(vinylidene fluoride)‐co‐hexafluoropropylene] (poly(VDF‐co‐HFP)) copolymer network. Accordingly, the hybrid SiO₂‐SO₃H/terpolymer/poly(VDF‐co‐HFP) copolymer membrane has potential use as an electrolyte in a polymer‐electrolyte‐membrane fuel cell operating at intermediate temperatures.     

Solventless Acid‐Free Synthesis of Mesostructured Titania: Nanovessels for Metal Complexes and Metal Nanoclusters

A new and highly reproducible method to obtain mesostructured titania materials is introduced in this contribution. The mesostructured titania is obtained by employing self‐assembled structures of non‐ionic alkyl‐poly(ethylene oxide) surfactants as templates. The materials are produced without additional solvents such as alcohols, or even water. Only the titanium(IV ) ethoxide and the surfactant (C₁₂EO₁₀) are needed. Water, in the form of that attached to the surfactant and from the atmosphere, induces growth of titania nanoclusters in the synthesis sol. It is indicated that these nanoclusters interact with the surfactant EO‐head groups to form a new titanotropic amphiphile. The new amphiphiles self‐assemble into titanium nanocluster–surfactant hybrid lyotropic phases, which are transformed to the final mesostructured materials by further condensation of the titania network. The titania materials can be obtained also with noble‐metal particles immobilized in the mesostructured framework. It is seen that when different metal salts are used as the metal precursors, different interactions with the titania walls are found. The materials are characterized by X‐ray diffraction (XRD), polarization optical microscopy (POM), transmission electron microscopy (TEM), UV‐vis spectroscopy, and micro‐Raman analysis.     

Watermelon‐Like Structured SiOx–TiO2@C Nanocomposite as a High‐Performance Lithium‐Ion Battery Anode

A unique watermelon‐like structured SiO_x–TiO₂@C nanocomposite is synthesized by a scalable sol–gel method combined with carbon coating process. Ultrafine TiO₂ nanocrystals are uniformly embedded inside SiO_x particles, forming SiO_x–TiO₂ dual‐phase cores, which are coated with outer carbon shells. The incorporation of TiO₂ component can effectively enhance the electronic and lithium ionic conductivities inside the SiO_x particles, release the structure stress caused by alloying/dealloying of Si component and maximize the capacity utilization by modifying the Si–O bond feature and decreasing the O/Si ratio (x‐value). The synergetic combination of these advantages enables the synthesized SiO_x–TiO₂@C nanocomposite to have excellent electrochemical performances, including high specific capacity, excellent rate capability, and stable long‐term cycleability. A stable specific capacity of ≈910 mAh g^?1 is achieved after 200 cycles at the current density of 0.1 A g^?1 and ≈700 mAh g^?1 at 1 A g^?1 for over 600 cycles. These results suggest a great promise of the proposed particle architecture, which may have potential applications in the improvement of various energy storage materials.     

Direct View on Nanoionic Proton Mobility

The field of nanoionics is of great importance for the development of superior materials for devices that rely on the transport of charged ions, like fuel cells, batteries, and sensors. Often nanostructuring leads to enhanced ionic mobilities due to the induced space‐charge effects. Here these large space‐charge effects occurring in composites of the proton‐donating solid acid CsHSO₄ and the proton‐accepting TiO₂ or SiO₂ are studied. CsHSO₄ is chosen for this study because it can operate effectively as a fuel‐cell electrolyte at elevated temperature while its low‐temperature conductivity is increased upon nano­structuring. The composites have a negative enthalpy of formation for defects involving the transfer of protons from the acid to the acceptor. Very high defect densities of up to 10% of the available sites are observed by neutron diffraction. The effect on the mobility of the protons is observed directly using quasielastic neutron scattering and nuclear magnetic resonance spectroscopy. Surprisingly large fractions of up to 25% of the hydrogen ions show orders‐of‐magnitude enhanced mobility in the nanostructured composites of TiO₂ or SiO₂, both in crystalline CsHSO₄ and an amorphous fraction.     

The Formation of Performance Enhancing Pseudo‐Composites in the Highly Active La1–xCaxFe0.8Ni0.2O3 System for IT‐SOFC Application

The La_1–xCa_xFe_0.8Ni_0.2O_3–δ (0 ≤ x ≤ 0.9) system is investigated for potential application as a cathode material for intermediate temperature solid oxide fuel cells (IT‐SOFCs). A broad range of experimental techniques have been utilized in order to elucidate the characteristics of the entire compositional range. Low A‐site Ca content compositions (x ≤ 0.4) feature a single perovskite solid solution. Compositions with 40% Ca content (x = 0.4) exhibit the highest electrical and ionic conductivities of these single phase materials (250 and 1.9 × 10^?3 S cm^?1 at 800 °C, respectively), a level competitive with state‐of‐the‐art (La,Sr)(Fe,Co)O₃. Between 40 and 50% Ca content (0.4 > x > 0.5) a solubility limit is reached and a secondary, brownmillerite‐type phase appears for all higher Ca content compositions (0.5 ≤ x ≤ 0.9). While typically seen as detrimental to electrochemical performance in cathode materials, this phase brings with it ionic conductivity at operational temperatures. This gives rise to the effective formation of pseudo‐composite materials which feature significantly enhanced performance characteristics, while also providing the closest match in thermal expansion behavior to typical electrolyte materials. This all comes with the advantage of being produced through a simple, single‐step, low‐cost production route without the issues associated with typical composite materials. The highest performing pseudo‐composite material (x = 0.5) exhibits electronic conductivity of 300–350 S cm^?1 in the 600–800 °C temperature range while the best polarisation resistance (R_p) values of approximately 0.2 Ω cm² are found in the 0.5 ≤ x ≤ 0.7 range.     

Rechargeable Na–SO2 Battery with Ethylenediamine Additive in Ether‐Based Electrolyte

Rechargeable metal–SO₂ batteries have drawn tremendous attention because it can accelerate SO₂ fixation/utilization and offer high energy density. Herein, a rechargeable Na–SO₂ battery based on an ether‐based liquid electrolyte with an ethylenediamine (EDA) additive is realized via the reversible formation/decomposition of Na₂S₂O₄. Experimental investigations reveal that the EDA additive provides three benefits by simultaneously decreasing the overall electrode polarization, increasing the full discharge capacity, and improving battery cyclability. At a current density of 250 mA g^?1, the full discharge capacity of the battery with the EDA additive is more than twice of a similar system in the absence of EDA. In addition to the significantly enhanced capacity, the as‐assembled Na–SO₂ battery demonstrates excellent cyclic stability after 200 cycles, which is equivalent to a total duration of 1600 h. Moreover, the corrosion resistance of Na anode is strengthened with the aid of EDA in the SO₂‐containing liquid electrolyte. This work will pave the way for Na–SO₂ batteries as a promising battery technology toward both pollutant gas utilization and energy storage.     

Chemically Stable Pr and Y Co‐Doped Barium Zirconate Electrolytes with High Proton Conductivity for Intermediate‐Temperature Solid Oxide Fuel Cells

A chemically stable and highly proton‐conductive electrolyte is developed by partially substituting the Zr site of Y‐doped barium zirconate (BZY) with 10 mol% of Pr. Compared to BZY, BaZr_0.7Pr_0.1Y_0.2O_3‐δ (BZPY) shows improved sinterability as revealed by dilatometric measurements and scanning electron microscopy (SEM) analysis. Dense samples are obtained after sintering at 1500?C for 8 h. Moreover, BZPY shows good chemical stability in the wide range of fuel‐cell operating conditions. The larger density and the enhanced grain growth, compared to BZY, allow the volume content of grain boundaries, which generally show a high resistance for proton transport, to be reduced and, thus, a high proton conductivity can be achieved in the temperature range of interest for practical applications (above 10^?2 Scm^?1 at 600?C). The good sinterability, chemical stability, and high conductivity of the BZPY electrolyte enabled the fabrication of single‐cell prototypes based on a thin BZPY membrane by a simple and cost‐saving co‐pressing method. Electrochemical impedance spectroscopy (EIS) analysis performed during fuel‐cell tests under open‐circuit conditions confirms the good electrical performance of BZPY as electrolyte material. To improve the present fuel‐cell performance adapted cathode materials for this BZPY electrolyte need to be developed.     

Low‐Cost Self‐Assembled Oxide Separator for Rechargeable Batteries

Rechargeable battery cells having a liquid electrolyte require a separator permeable to the electrolyte between the two electrodes. Because the electrodes change their volume during charge and discharge, the porous separators are flexible polymers with an electronic energy gap E_g large enough for the Fermi levels of the two electrodes to be within it. In this work, a porous film of self‐assembled SiO₂ nanoparticles is developed as the separator for a Li‐ion battery with a liquid electrolyte. This coating does not require the plasticity of a polymer membrane and has the required large E_g. If adsorbed water is removed from the SiO₂ surface, the nanoparticles bond to one another and to an oxide cathode to form a plastic self‐assembling porous layer into which the liquid electrolyte can penetrate. The Li‐ion batteries with a LiCoO₂ cathode coated with SiO₂ as a separator show similar performance to cells with a traditional polypropylene separator and improved cyclability with a reduced volume of liquid electrolyte owing to the electrolyte wetting properties of the SiO₂ nanoparticles. The SiO₂ nanoparticles are easy to prepare, cheap, and environmentally friendly.     

Improved Hydrogen Production of Au–Pt–CdS Hetero‐Nanostructures by Efficient Plasmon‐Induced Multipathway Electron Transfer

The design of new functional materials with excellent hydrogen production activity under visible‐light irradiation has critical significance for solving the energy crisis. A well‐controlled synthesis strategy is developed to prepare an Au–Pt–CdS hetero‐nanostructure, in which each component of Au, Pt, and CdS has direct contact with the other two materials; Pt is on the tips and a CdS layer along the sides of an Au nanotriangle (NT), which exhibits excellent photocatalytic activity for hydrogen production under light irradiation (λ > 420 nm). The sequential growth and surfactant‐dependent deposition produce the three‐component Au–Pt–CdS hybrids with the Au NT acting as core while Pt and CdS serve as a co‐shell. Due to the presence of the Au NT cores, the Au–Pt–CdS nanostructures possess highly enhanced light‐harvesting and strong local‐electric‐field enhancement. Moreover, the intimate and multi‐interface contact generates multiple electron‐transfer pathways (Au to CdS, CdS to Pt and Au to Pt) which guide photoexcited electrons to the co‐catalyst Pt for an efficient hydrogen reduction reaction. By evaluating the hydrogen production rate when aqueous Na₂SO₃–Na₂S solution is used as sacrificial agent, the Au–Pt–CdS hybrid exhibits excellent photocatalytic activity that is about 2.5 and 1.4 times larger than those of CdS/Pt and Au@CdS/Pt, respectively.     

New Apatite‐Type Oxide Ion Conductor,Bi2La8[(GeO4)6]O3: Structure,Properties, and Direct Imaging of Low‐Level Interstitial Oxygen Atoms Using Aberration‐Corrected Scanning Transmission Electron Microscopy

The new solid electrolyte Bi₂La₈[(GeO₄)₆]O₃ is prepared and characterized by variable‐temperature synchrotron X‐ray and neutron diffraction, aberration‐corrected scanning transmission electron microscopy, and physical property measurements (impedance spectroscopy and second harmonic generation). The material is a triclinic variant of the apatite structure type and owes its ionic conductivity to the presence of oxide ion interstitials. A combination of annular bright‐field scanning transmission electron microscopy experiments and frozen‐phonon multislice simulations enables direct imaging of the crucial interstitial oxygen atoms present at a level of 8 out of 1030 electrons per formula unit of the material, and crystallographically disordered, in the unit cell. Scanning transmission electron microscopy also leads to a direct observation of the local departures from the centrosymmetric average structure determined by diffraction. As no second harmonic generation signal is observed, these displacements are non‐cooperative on the longer length scales probed by optical methods.     

Hierarchical Inorganic–Organic Nanocomposites Possessing Amphiphilic and Morphological Complexities: Influence of Nanofiller Dispersion on Mechanical Performance

Novel nanocomposites possessing ternary compositions and complex morphologies have been prepared from amphiphilic crosslinked hyperbranched fluoropolymer–poly(ethylene glycol) (HBFP–PEG) in the presence of pristine and chemically functionalized nanoscopic fillers, single‐walled carbon nanotubes (SWNTs) and silica nanoparticles (SiO₂). Both SWNTs and SiO₂ were engineered specifically to become phase‐designated reinforcing functional materials, SWNT‐g‐PEG and SiO₂‐g‐HBFP, which (1) improved the dispersion of fillers, nanotubes, or spherical nanoparticles in the amphiphilic matrices, (2) enhanced the non‐covalent interactions between nanofillers and polymers, and more importantly, (3) maintained reactive functionalities to be further covalently integrated into the complex networks. Tensile moduli (E_dry) for these as‐prepared SWNT‐containing composites increased by up to 430% relative to the unfilled material, while those incorporated with SiO₂ had a 420% increase of E_dry. After swelling in water, the water absorption within the micro‐ and nanochannels of PEG‐rich domains rigidified or softened the entire crosslinked network, as determined by the amount of PEG.     

SiO2/TiO2 Composite Film for High Capacity and Excellent Cycling Stability in Lithium‐Ion Battery Anodes

In this study, partially crystalline anodic TiO₂ with SiO₂ well‐distributed througout the entire oxide film is prepared using plasma electrolytic oxidation (PEO) to obtain a high‐capacity anode with an excellent cycling stability for Li‐ion batteries. The micropore sizes in the anodic film become inhomogeneous as the SiO₂ content is increased from 0% to 25%. The X‐ray diffraction peaks show that the formed oxide contains the anatase and rutile phases of TiO₂. In addition, X‐ray photoelectron spectroscopy and energy‐dispersive X‐ray analyses confirm that TiO₂ contains amorphous SiO₂. Anodic oxides of the SiO₂/TiO₂ composite prepared by PEO in 0.2 m H₂SO₄ and 0.4 m Na₂SiO₃ electrolyte deliver the best performance in Li‐ion batteries, exhibiting a capacity of 240 µAh cm^?2 at a fairly high current density of 500 µA cm^–2. The composite film shows the typical Li–TiO₂ and Li–SiO₂ redox peaks in the cyclic voltammogram and a corresponding plateau in the galvanostatic charge/discharge curves. The as‐prepared SiO₂/TiO₂ composite anode shows at least twice the capacity of other types of binder‐free TiO₂ and TiO₂ composites and very stable cycling stability for more than 250 cycles despite the severe mechanical stress.     

Sequential Hydroboration–Alcoholysis and Epoxidation–Ring Opening Reactions of Vinyl Groups in Mesoporous Vinylsilica

We report the sequential transformation of vinyl groups into hydroborate and alcohol as well as vinyl into epoxide and diol functional groups in hexagonal mesoporous vinylsilica materials, denoted meso‐vinyl‐SiO₂. The first transformation proceeds quantitatively through the hydroborylated derivative. After appropriate quenching, the hydroborylated materials are stable at ambient conditions and can undergo transformation into alcohols and various other functional groups. The pore volume and pore size uniformity were found not to be greatly affected by quenching of the hydroboranes with methanol, but they were reduced by quenching with water due to the deposition of boron‐containing species in the channels. Complete conversion of hydroborylated materials to alcohol‐functionalized materials required basic conditions and treatment time of several hours. Although this led to a significant structural shrinkage, decrease in pore volume, and decrease in ordering, there was no evidence of a partial collapse or removal of substantial parts of the pore walls under optimized synthesis conditions. This is the first successful conversion of organic groups of a functionalized ordered mesoporous silica host in alkaline solution, conditions known to be detrimental for silica frameworks. Epoxidation of the vinyl groups and subsequent conversion of the resulting epoxides into diols are also briefly described. The chemical transformation through epoxidation affords ordered mesoporous silica materials functionalized with potentially chiral organic groups, which could find applications in asymmetric catalysis and chiral separations. It was found that the epoxidation was slower than hydroboration and resulted in a lower degree of conversion. These two examples of hydroboration–alcoholysis and epoxidation–ring opening reactions of terminally bonded vinyl groups in meso‐vinyl‐SiO₂ demonstrate the novel concept of sequential organic chemical transformations harbored inside the ordered channels of mesoporous organosilica materials.     

Preparation and measurement of highly efficient a‐Si:H single junction solar cells and the advantages of μc‐SiOx:H n‐layers

Reducing the optical losses and increasing the reflection while maintaining the function of doped layers at the back contact in solar cells are important issues for many photovoltaic applications. One approach is to use doped microcrystalline silicon oxide (μc‐SiO_x:H) with lower optical absorption in the spectral range of interest (300 nm to 1100 nm). To investigate the advantages, we applied the μc‐SiO_x:H n‐layers to a‐Si:H single junction solar cells. We report on the comparison between amorphous silicon (a‐Si:H) single junction solar cells with either μc‐SiO_x:H n‐layers or non‐alloyed silicon n‐layers. The origin of the improved performance of a‐Si:H single junction solar cells with the μc‐SiO_x:H n‐layer is identified by distinguishing the contributions because of the increased transparency and the reduced refractive index of the μc‐SiO_x:H material. The solar cell parameters of a‐Si:H solar cells with both types of n‐layers were compared in the initial state and after 1000 h of light soaking in a series of solar cells with various absorber layer thicknesses. The measurement procedure for the determination of the solar cell performance is described in detail, and the measurement accuracy is evaluated and discussed. For an a‐Si:H single junction solar cell with a μc‐SiO_x:H n‐layer, a stabilized efficiency of 10.3% after 1000 h light soaking is demonstrated. Copyright © 2015 John Wiley & Sons, Ltd.     

Understanding the Host–Guest Interaction Between Responsive Core‐Crosslinked Hybrid Nanoparticles of Hyperbranched Poly(ether amine) and Dyes: The Selective Adsorption and Smart Separation of Dyes in Water

The host–guest interaction between polymer nanoparticles and guest molecules plays a key role in fields such as controlled drug delivery, separation, and nanosensors. To understand this host–guest interaction, a series of hybrid polymer nanoparticles (SiO_1.5‐hPEA NPs) are designed and prepared based on hyperbranched poly(ether amine) (hPEA) with the different hydrophobicity and functional groups. Their adsorption behavior to twelve hydrophilic dyes in aqueous solution is studied. The core‐crosslinked hybrid nanoparticles (SiO_1.5‐hPEA NPs) are prepared by direct dispersion of hPEA containing trimethoxysilyl moieties (TMS‐hPEA) in aqueous solution, which exhibit sharp multiresponse to temperature, pH, and ionic strength in aqueous solution. The effect of molecular structure of TMS‐hPEA on the host–guest interaction between SiO_1.5‐hPEA NPs and hydrophilic dyes is investigated in detail. The obtained SiO_1.5‐hPEA NPs interact selectively with different hydrophilic dyes in aqueous solution. The distribution coefficient (K) for partitioning of dyes between SiO_1.5‐hPEA NPs and water is proposed to define the strength of the host‐guest interaction between the nanoparticles and dyes. K increases with the increasing hydrophobicity of the hPEA backbone regardless of their charge states of SiO_1.5‐hPEA NPs and dyes. A methodology is demonstrated for the smart separation of a mixture of dyes in water using SiO_1.5‐hPEA NPs.     

Single‐Atom Fe‐Nx‐C as an Efficient Electrocatalyst for Zinc–Air Batteries

Highly efficient non‐noble metal electrocatalysts are vital for metal–air batteries and fuel cells. Herein, a noble‐metal–free single‐atom Fe‐N _x‐C electrocatalyst is synthesized by incorporating Fe‐Phen complexes into the nanocages in situ during the growth of ZIF‐8, followed by pyrolysis at 900 °C under inert atmosphere. Fe‐Phen species provide both Fe²⁺ and the organic ligand (Phen) simultaneously, which play significant roles in preparing single‐atom catalysts. The obtained Fe‐N_x‐C exhibits a half‐wave potential of 0.91 V for the oxygen reduction reaction, higher than that of commercial Pt/C (0.82 V). As a cathode catalyst for primary zinc–air batteries (ZABs), the battery shows excellent electrochemical performances in terms of the high open‐circuit voltage (OCV) of 1.51 V and a high power density of 96.4 mW cm^?2. The rechargeable ZAB with Fe‐N_x‐C catalyst and the alkaline electrolyte shows a remarkable cycling performance for 300 h with an initial round‐trip efficiency of 59.6%. Furthermore, the rechargeable all‐solid‐state ZABs with the Fe‐N_x‐C catalyst show high OCV of 1.49 V, long cycle life for 120 h, and foldability. The single‐atom Fe‐N_x‐C electrocatalyst may function as a promising catalyst for various metal–air batteries and fuel cells.     

A New Family of Proton‐Conducting Electrolytes for Reversible Solid Oxide Cells: BaHfxCe0.8−xY0.1Yb0.1O3−δ

Reversible solid oxide cells based on ceramic proton conductors have potential to be the most efficient system for large‐scale energy storage. The performance and long‐term durability of these systems, however, are often limited by the ionic conductivity or stability of the proton‐conducting electrolyte. Here new family of solid oxide electrolytes, BaHf_xCe_0.8?xY_0.1Yb_0.1O_3?δ (BHCYYb), which demonstrate a superior ionic conductivity to stability trade‐off than the state‐of‐the‐art proton conductors, BaZr_xCe_0.8?xY_0.1Yb_0.1O_3?δ (BZCYYb), at similar Zr/Hf concentrations, as confirmed by thermogravimetric analysis, Raman, and X‐ray diffraction analysis of samples over 500 h of testing are reported. The increase in performance is revealed through thermodynamic arguments and first‐principle calculations. In addition, lab scale full cells are fabricated, demonstrating high peak power densities of 1.1, 1.4, and 1.6 W cm^?2 at 600, 650, and 700 °C, respectively. Round‐trip efficiencies for steam electrolysis at 1 A cm^?2 are 78%, 72%, and 62% at 700, 650, and 600 °C, respectively. Finally, CO₂? H₂O electrolysis is carried out for over 700 h with no degradation.     

An In Situ Formed,Dual‐Phase Cathode with a Highly Active Catalyst Coating for Protonic Ceramic Fuel Cells

Composite cathodes of solid oxide fuel cells (SOFCs) are normally fabricated by mechanical mixing of electronic‐ and ionic‐conducting phases. Here, a dual‐phase SOFC cathode, composed of perovskite PrNi_0.5Mn_0.5O₃ (PNM) and exsoluted fluorite PrO_x particles, produced in situ through a glycine–nitrate solution combustion process, is reported. When applied as the cathode for a BaZr_0.1Ce_0.7Y_0.1Yb_0.1O₃‐based protonic ceramic fuel cell, the hybrid cathode displays excellent electrocatalytic activity (area‐specific resistance of 0.052 Ω cm² at 700 °C) and remarkable long‐term stability when operated at a cell voltage of 0.7 V for ≈500 h using H₂ as fuel and ambient air as oxidant. The excellent performance is attributed to the proton‐conducting BaPrO₃‐based coating and high‐concentration oxygen vacancies of a Ba‐doped PNM surface coating, produced by the reaction between the cathode and Ba from the electrolyte (via evaporation or diffusion), as confirmed by detailed X‐ray photoelectron spectroscopy, Raman spectroscopy, and density functional theory‐based calculations.     

High‐Throughput Fabrication of Au–Cu Nanoparticle Libraries by Combinatorial Sputtering in Ionic Liquids

Materials libraries of binary alloy nanoparticles (NPs) are synthesized by combinatorial co‐sputter deposition of Cu and Au into the ionic liquid (IL) 1‐butyl‐3‐methylimidazolium bis(trifluoromethylsulfonyl)imide ([C₁C₄im][Tf₂N]), which is contained in a micromachined cavity array substrate. The resulting NPs and NP‐suspensions are investigated by transmission electron microscopy (TEM), X‐ray diffraction (XRD), UV‐Vis measurements (UV‐Vis), and attenuated total reflection Fourier transformed infrared (ATR‐FTIR) spectroscopy. Whereas the NPs can be directly observed in the IL using TEM, for XRD measurements the NP concentration is too low to lead to satisfactory results. Thus, a new NP isolation process involving capping agents is developed which enables separation of NPs from the IL without changing their size, morphology, composition, and state of aggregation. The results of the NP characterization show that next to the unary Cu and Au NPs, both stoichiometric and non‐stoichiometric Cu–Au NPs smaller than 7 nm can be readily obtained. Whereas the size and shape of the alloy NPs change with alloy composition, for a fixed composition the NPs have a small size distribution. The measured lattice constants of all capped NPs show unexpected increased values, which could be related to the NP/surfactant interactions.     

Functional Chromium Wheel‐Based Hybrid Organic–Inorganic Materials for Dielectric Applications

The first example of organic–inorganic hybrid materials based on the embedding of a chromium–nickel wheel cluster {[(n‐C₃H₇)₂NH₂]‐ [Cr₇NiF₈(O₂C₄H₅)₁₆]} (Cr7Ni) into poly(methyl methacrylate) (PMMA) and the characterization of the dielectric properties of the obtained material is described. By an optimized copolymerization of the methacrylate‐functionalized chromium–nickel wheel with methyl methacrylate in a cluster/monomer 1:200 molar mixture, a homogeneous hybrid material CrNi_MMA200 is obtained. The electrical responses of the non‐doped PMMA and of the hybrid material were studied by broadband dielectric spectroscopy (BDS) from 0.01 Hz to 10 MHz and over the temperature range of 5–115 °C. The permittivity profiles reveal two relaxation peaks in the materials, which correspond to the α and β relaxation modes of the PMMA matrix. The position of these modes shifts toward higher frequencies as temperature increases. BDS is a powerful tool revealing the intimate miscibility of the various components of the hybrid material, thus indicating that, on a molecular scale, the material proposed is a homogeneous system. Finally, a value of the dielectric constant of 2.9 at 25 °C and 1 kHz is determined. This value is noticeably lower than the value of 3.2 obtained for pristine PMMA prepared following the same synthesis protocol. Thus, these results classify the hybrid CrNi_MMA200 as an appealing starting material for the development of dielectric polymeric layers for the development of innovative capacitors, transistors, and other microelectronic devices. The vibrational properties of the hybrid materials are investigated by Fourier‐transform infrared (FT‐IR) and Raman spectroscopy, whereas the thermal behavior is analyzed by thermogravimetric analysis (TGA). Swelling experiments are used to qualitatively evaluate the crosslinking density of the hybrid materials. The integrity of the wheels once embedded in the macromolecular backbone is confirmed by extended X‐ray absorption fine structure (EXAFS) and electron spin resonance (EPR) spectroscopic measurements.