Redox‐Mediated Synthesis of a Fe3O4–MnO2 Nanocomposite for Dye Adsorption and Pseudocapacitance

A logically chosen redox reaction of submerged Fe⁰ in an aqueous KMnO₄ solution has been reported. The template‐free reaction conditions produced gram amounts of a hierarchical flowerlike Fe₃O₄–MnO₂ nanocomposite. More precisely, freshly prepared Fe⁰ nanoparticles were prepared from air‐free hot water under submerged conditions using a door magnet. The black Fe⁰ particles were oxidized in water quantitatively by KMnO₄ in the solution phase and the nanocomposite was prepared. The material has been used as a dye adsorbent and the representative cationic dye uptake, recovery, and recycling of the dye becomes easy owing to the ferromagnetic properties and surface negative charge of the material. The nanocomposite also showed a higher specific capacitance (327 F g^?1 at 10 mV s^?1) than the reported values of pure MnO₂ and Fe₃O₄. The material exhibited a high energy density as well as a high power density, and remained stable even after a large number of charge–discharge cycles.     

A Dendritic Nanostructured Copper Oxide Electrocatalyst for the Oxygen Evolution Reaction

To use water as the source of electrons for proton or CO₂ reduction within electrocatalytic devices, catalysts are required for facilitating the proton‐coupled multi‐electron oxygen evolution reaction (OER, 2 H₂O→O₂+4 H⁺+4 e⁻). These catalysts, ideally based on cheap and earth abundant metals, have to display high activity at low overpotential and good stability and selectivity. While numerous examples of Co, Mn, and Ni catalysts were recently reported for water oxidation, only few examples were reported using copper, despite promising efficiencies. A rationally designed nanostructured copper/copper oxide electrocatalyst for OER is presented. This material derives from conductive copper foam passivated by a copper oxide layer and further nanostructured by electrodeposition of CuO nanoparticles. The generated electrodes are highly efficient for catalyzing selective water oxidation to dioxygen with an overpotential of 290 mV at 10 mA cm⁻² in 1 m NaOH solution.     

Porous Molybdenum‐Based Hybrid Catalysts for Highly Efficient Hydrogen Evolution

We have synthesized a porous Mo‐based composite obtained from a polyoxometalate‐based metal–organic framework and graphene oxide (POMOFs/GO) using a simple one‐pot method. The MoO₂@PC‐RGO hybrid material derived from the POMOFs/GO composite is prepared at a relatively low carbonization temperature, which presents a superior activity for the hydrogen‐evolution reaction (HER) in acidic media owing to the synergistic effects among highly dispersive MoO₂ particles, phosphorus‐doped porous carbon, and RGO substrates. MoO₂@PC‐RGO exhibits a very positive onset potential close to that of 20 % Pt/C, low Tafel slope of 41 mV dec^?1, high exchange current density of 4.8×10^?4 A cm^?2, and remarkable long‐term cycle stability. It is one of the best high‐performance catalysts among the reported nonprecious metal catalysts for HER to date.     

Flower-like NiCo-carbonate Hydroxides for High-performance Solid-state Hybrid Supercapacitor

Compared to the traditional transition metal layered double hydroxides, transition metal layered carbonate double hydroxides (TMC-LDHs) possess superior electrochemical performance in theory. But TMC-LDHs have not received its deserved attention, especially for application in the energy storage field. In this work, a flower-like TMC-LDH (Ni_0.75Co_0.25(CO₃)_0.125(OH)₂, NCCO) material was successfully prepared by hydrothermal method, which exhibits a high specific capacity of 306.8 mAh g⁻¹ (0.52 mAh cm⁻²) at 0.5 A g⁻¹ with capacity retention of 70.5 % after 2000 cycles. The solid-state hybrid supercapacitor device NCCO//PVA/KOH//IHPC based on the prepared NCCO material and an interconnected hierarchical porous carbon (IHPC) delivers a high specific energy of 50.96 Wh kg⁻¹ at a specific power of 1.06 kW kg⁻¹, and a high specific energy of 36.39 Wh kg⁻¹ still can be delivered at a high specific power of 10.49 kW kg⁻¹. More than 181.2 % of initial specific capacity is retained after 12000 cycles. The specific energy, energy retention under large specific power, and the cycle stability of the assembled device are better than most of the solid-state hybrid supercapacitors that have been reported. These results demonstrate the promising prospect of the TMC-LDH material in the practical application in advanced solid-state supercapacitors.     

Controllable Synthesis of Mesoporous Iron Oxide Nanoparticle Assemblies for Chemoselective Catalytic Reduction of Nitroarenes

Iron(III) oxide is a low‐cost material with applications ranging from electronics to magnetism, and catalysis. Recent efforts have targeted new nanostructured forms of Fe₂O₃ with high surface area‐to‐volume ratio and large pore volume. Herein, the synthesis of 3D mesoporous networks consisting of 4–5 nm γ‐Fe₂O₃ nanoparticles by a polymer‐assisted aggregating self‐assembly method is reported. Iron oxide assemblies obtained from the hybrid networks after heat treatment have an open‐pore structure with high surface area (up to 167 m² g^?1) and uniform pores (ca. 6.3 nm). The constituent iron oxide nanocrystals can undergo controllable phase transition from γ‐Fe₂O₃ to α‐Fe₂O₃ and to Fe₃O₄ under different annealing conditions while maintaining the 3D structure and open porosity. These new ensemble structures exhibit high catalytic activity and stability for the selective reduction of aryl and alkyl nitro compounds to the corresponding aryl amines and oximes, even in large‐scale synthesis.     

A new layered indium selenium oxychloride material: Synthesis,structure, and characterization of InSeO3Cl

A new layered indium selenium oxychloride material, InSeO₃Cl has been synthesized by a standard solid-state reaction using In₂O₃, InCl₃, and SeO₂ as reagents. Single-crystal X-ray diffraction was used to determine the structure of the reported material. InSeO₃Cl crystallizes in the orthorhombic space group Pbca (No. 61), with a = 7.0580(14) Å, b = 7.0390(14) Å, c = 16.206(3) Å, V = 805.1(3) Å³, and Z = 8. InSeO₃Cl has a layered structure consisting of distorted InO₄Cl₂ octahedra and SeO₃ polyhedra. The Se⁴⁺ cations are in asymmetric coordination environment attributed to their stereoactive lone pairs. The lone pairs on the Se⁴⁺ cations approximately point in the [101], [?10-1], [10-1], and [?101] direction. A separation of the halophile and the chalcophile moieties is observed from the reported material. Detailed structural analysis with full characterization including infrared spectroscopy, bond valence calculations, thermogravimetric analysis, elemental analysis, and dipole moment calculations are reported.     

Some Physico-Technical Aspects of the New Generation of Self-Calibrated Alanine/EPR Dosimeter and Results from the International Intercomparison trial

Some physico-technical parameters of the self-calibrated alanine/EPR dosimeters are described. Principally, this new type of solid state/EPR dosimeter contains radiation sensitive diamagnetic material (in the present case, alanine), some quantity of EPR active, but radiation insensitive, substance (for example, Mn²⁺/MgO) playing roles of an internal standard and a binding material. Thus with this dosimeter the EPR spectra of alanine and the internal standard Mn²⁺ are recorded simultaneously and the dose response is represented as a ratio of EPR signal intensities of alanine versus Mn²⁺ as a function of absorbed dose. As a result, the data of the present study have shown that there is practically no interference of the dosimeter EPR response (expressed as the ratio I _alanine/I _Mn) from the way of preparation (homogeneity), behavior after irradiation (fading of EPR signals with time, influence of different meteorological conditions) as well as specific spectrometer setting conditions. These dosimeters show satisfactory reproducibility of preparation and reading as well as stability on keeping. Thus, fulfilling the described physico-technical data of this type of dosimeters, the reproducibility of the readings is significantly improved particularly when intercomparison among different laboratories is performed. This conclusion is confirmed by independent studies of the described self-calibrated alanine/EPR dosimeters in several laboratories in Europe. Results of which are also reported.     

Fluorolytic Sol–Gel Route and Electrochemical Properties of Polyanionic Transition-Metal Phosphate Fluorides

Fluorine-containing polyanionic compounds have attracted much attention in the last few years as potential positive electrode materials for rechargeable batteries. With their formula A_aM_bX_cO₄Y_d (A=Li, Na…; M=Ti, V, Mn, Fe, Co, Ni…; X=P or S, and Y=F, OH, O), they offer a very rich chemistry and their electrochemical properties can be tuned by carefully choosing the different constituting elements. However, synthesis approaches that allow these materials to be obtained at low temperature are almost nonexistent. In this paper, the use of a nonaqueous fluorolytic sol–gel approach is reported to synthesize a tavorite-type LiFePO₄F material and its electrochemical characterization was performed. The obtained material displays an electrochemical performance that positively compares with the literature with an excellent cycling stability (115 mA h⁻¹ g⁻¹ after 100 cycles at C/2 rate). A slight change in the synthesis parameters allowed Li₂CoPO₄F to be successfully obtained, demonstrating the versatility of the reported route, which can be adapted to synthesize other fluorine-containing polyanionic compounds, which are of great interest for energy storage applications.     

Electrocatalytic applications of a sol–gel derived cobalt phthalocyanine–dispersed carbon–ceramic electrode

The preparation and characterization of a surface renewable carbon–ceramic electrode, SiO₂/SnO₂/C-graphite/(SiPy⁺)₄CoPcTs⁻⁴, is reported. Cobalt(II) tetrasulfonated phthalocyanine (CoPcTs⁻⁴) absorbed on a 3-n-propylpyridinium chloride silsesquioxane polymer was dispersed in a stannic-silica C-graphite sol–gel matrix. The performance of SiO₂/SnO₂/C-graphite/(SiPy⁺)₄CoPcTs⁻⁴ as electrode material was investigated by cyclic voltammetry in the electrocatalytic oxidation of oxalic acid and nitrite. The modified carbon–ceramic material was characterized by X-ray fluorescence spectroscopy, BET specific surface area, thermogravimetric analysis, X-ray photoelectron spectroscopy, and scanning electron microscopy.     

Synthesis and Structural Elucidation of Sulfonated Naphthalene-Formaldehyde

The synthesis, characterization, structural elucidation, and application of the dispersant obtained from the condensation of β -naphthalene sulfonic acid and formaldehyde are reported. The one-pot synthesis from naphthalene, sulfuric acid, and formaldehyde leads to reproducible polymers with 13 and 14 naphthalene nuclei. The ¹ H and ¹³ C NMR spectra in D ₂ O (representative spherical shape) and DMSO (representative rod-like shape) are reported. The belching technique led to excellent super pure material.     

A synthesis of porous activated carbon materials derived from vitamin B9 base for CO2 capture and conversion

CO₂ capture and conversion are still a favorable way to reduce CO₂ in the atmosphere. Herein, we have developed an environmentally friendly, low energy consumption porous activated carbon from vitamin B9 carbonaceous material for CO₂ capture and conversion materials. It is demonstrated that the KOH/vitamin B9 carbonaceous material impregnation ratio of 2 is the optimum condition for obtaining porous activated carbons with high specific surface area of 1903 m²g^-1, micropore surface area of 710 m²g^-1, total pore volume of 1.05 cm³g^-1 and micropore volume of 0.38 cm³g^-1. Among all the porous activated carbons prepared, the porous activated carbon synthesized with the KOH/vitamin B9 carbonaceous material impregnation ratio of 2 registers the most excellent CO₂ capture for 5.41 mmolg^?1 at 0 °C/1 bar and 3.66 mmolg^?1 at 25 °C/1 bar. They can also effectively catalyze the cycloaddition of CO₂ and epoxides under mild conditions (1 bar, 100 °C and 8 h) with a yield of 89–94%. The synthesized porous carbon materials from vitamin B9 is a promising candidate material for CO₂ capture and fixation.     

A monoclinic form of anhydrous Cs2PdCl4

A previously unreported monoclinic form of Cs₂PdCl₄ is described. It is found to transform into the reported orthorhombic form on exposure to atmospheric moisture. Infrared spectroscopy and TGA analysis of the previously reported orthorhombic form of Cs₂PdCl₄ reveals that it is a hydrate with a formula of approximately Cs₂PdCl₄:4H₂O. Water is not present in the monoclinic material. The compound is non-magnetic, which is attributed to a low spin configuration for 4 d⁸ Pd²⁺ in square planar coordination with Cl. The band gaps of the two forms are found to be 2.13 and 2.21 eV, consistent with their colors. A DFT-calculated electronic structure for the monoclinic form is presented.     

A preliminary investigation of the thermal and X-ray induced degradation of cellulose nitrates by FAB/SIMS and 13C NMR

Some surface aspects of the thermal and X-ray induced degradation of a cellulose nitrate have been studied by FAB/SIMS.The pristine material gives peaks at 30 and 46 amu, indicative of NO⁺ and NO₂⁺ originating from the nitrate ester groups. The thermally degraded material indicates these peaks at slightly lower intensities, whereas the X-ray degraded material shows little evidence for their appearance. These data complement recent ESCA data on the same systems.¹The conclusion is that electromagnetic degradation is predominantly a surface effect, whereas thermal degradation is a bulk oriented phenomenon. ¹³C nmr has been used to add further evidence for this last point.     

Luminescent Hybrid Materials Based on Laponite Clay

The spectroscopic behavior of ionic Eu³⁺ or Tb³⁺ complexes of an aromatic carboxyl‐functionalized organic salt as well as those of the hybrid materials derived from adsorption of the ionic complexes on Laponite clay are reported. X‐ray diffraction (XRD) patterns suggest that the complexes are mainly adsorbed on the outer surfaces of the Laponite disks rather than intercalated within the interlayer spaces. Photophysical data showed that the energy‐transfer efficiency from the ligand to Eu³⁺ ions in the hybrid material is increased remarkably with respect to the corresponding ionic complex. The hybrid material containing the Eu³⁺ complex shows bright red emission from the prominent ⁵D₀→⁷F₂ transition of Eu³⁺ ions, and that containing the Tb³⁺ complex exhibits bright green emission due to the dominant ⁵D₄→⁷F₅ transition of Tb³⁺ ions.     

Eco‐friendly synthesis of benzoxazepine and malonamide derivatives in aqueous media

A special, efficient and reusable heterogeneous catalytic system is reported for the one‐pot three‐component synthesis of a series of malonamide and 2,3,4,5‐tetrahydrobenzo[b][1,4]oxazepine derivatives in the presence of a heterogeneous material composed of MCM‐48/H₅PW₁₀V₂O₄₀ in aqueous media and at room temperature. The products were identified using physical data (melting points) by comparison with those reported in the literature. Also, the structures of the new compounds were characterized by means of infrared, ¹H NMR, ¹³C NMR and CHN analyses. Copyright © 2016 John Wiley & Sons, Ltd.     

Novel functionalized ionic liquid with a sulfur atom in the aliphatic side chain of the pyrrolidinium cation

A novel ionic liquid, never reported in literature until now, was properly designed, synthesized and preliminary investigated. This material was prepared combining the N-methylpyrrolidinium cation (PYR_1(2S1))⁺, exhibiting a sulfur atom in the alkyl side chain, with the bis(trifluoromethanesulfonyl)imide anion, (TFSI)⁻, to be addressed as safer electrolyte component for sulfur-based battery systems. The presence of sulfur within the cation side chain was found to prevent the crystallization of the ionic liquid even in the presence of lithium salt. Cyclic voltammetries have clearly indicated that Li⁺ cation exhibits good mobility and is reversibly plated/stripped in PYR_1(2S1)TFSI–LiTFSI electrolytes with high efficiency.     

A New Silicate Clathrate Hydrate: An X-Ray Diffraction and Nuclear Magnetic Resonance Study of a System with Octameric Silicate Anions and Trivalent Cations

The first crystal structure is reported for a silicate clathrate hydrate involving a triply charged cation [C₁₈H₃₀N₃]³⁺ and an octameric cubic silicate cage. The structure is essentially a host/guest system, with the silicate cages linked into a framework by hydrogen bonding to water molecules. The space group is P with Z = 2, and the asymmetric unit includes a complete cation and half the anion, plus 21 water molecules (4 of which are in disordered positions). Solid-state (CPMAS) ²⁹Si and ¹³CNMR spectra are consistent with the diffraction-determined structure and indicate substantial distortion of the anion from cubic symmetry. Solution-state spectra of precursor solutions and of melted material are also presented and discussed.     

Molecular Clusters in Mesoporous Materials as Precursors to Nanoparticles of a New Lacunar Ternary Compound Pd x Mo y P

Bimetallic clusters of composition Pd₂Mo₂(η⁵-C₅H₅)₂(μ₃-CO)₂(μ₂-CO)₄(PR₃)₂ (R = ethyl or phenyl) were incorporated by impregnation from solution into two different silica matrices, amorphous xerogels and ordered SBA-15, and a study of their thermal decomposition under a reducing atmosphere is reported. With both matrices, a suitable thermal treatment afforded nanoparticles of a new bimetallic phosphide. Although nanoparticles of composition Pd _x Mo _y P, isostructural with Mo₃P, were formed in both matrices, they were more uniformly distributed in the SBA-15 framework and showed a narrower size distribution. The samples have been characterized by powder XRD, chemical analysis, FT-IR spectroscopy, TEM and electron tomography (3D TEM). Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Electrochemical oxidation of a carbon black loaded polymer electrode in aqueous electrolytes

The suitability of a polymeric composite material for use as part of an anode structure in a cathodic protection system has been examined. The composite material was a conductive blend (volume resistivity typically 1.5 Ω cm) of carbon black in a polyethylene binder. A long operational lifetime for the material demands that the rate of carbon loss must be low. In the work reported here, electrochemical and in situ analytical techniques were employed to characterise the performance of the material over a wide range of anodic current densities in a variety of aqueous electrolytes. The predominant anodic electrochemical reaction on the polymeric material is CO₂ formation in acid and neutral solutions, which causes loss of carbon from the surface and the development of a non-conducting layer of polyethylene. The characteristics of the reaction suggest that it occurs via the discharge of H₂O. In alkaline pH, however, the anodic reactions are more complex. A high OH⁻ concentration (pH 12 or higher) favours the formation of oxygen rather than CO₂, particularly at low anodic potentials. The presence of CO₃ ²⁻ in the electrolyte catalyses the evolution of oxygen at pH values as low as 9. The electrochemical formation of oxygen always occurs in parallel with the generation of some humic acid in the solution. Received: 23 July 1998 / Accepted: 17 November 1998     

Direct synthesis of hydrogen peroxide in microreactors

Several studies concerning direct synthesis of hydrogen peroxide in microreactors are reviewed. Several types of microreactors have been applied. Their high surface area-to-volume ratio and small internal volume improve safety, which is required when operating with explosive gases. The tested microreactors represent capillary reactors and more sophisticated reactors with a special plate structure on which reaction channels have been machined. Both single- and multi-channel arrangements have been applied. The catalysts have been installed in the reactor in the form of powder or washcoat layer on the channel wall. Palladium and platinum on various support material, such as SiO₂, Al₂O₃ and C, have been tested. Water was the most common solvent, but also methanol, ethanol, and isopropanol have been used because of their better gas dissolving properties. In addition to solvents, chemicals, often called promoters, have been utilised to improve productivity. The most typical promoters were halide ions, such as Br^? and Cl^? and inorganic acids. Hydrogen peroxide has been produced successfully by several research groups. The highest reported mass fraction of hydrogen peroxide was 5 wt %.