Multivalent metal–sulfur batteries for green and cost-effective energy storage: Current status and challenges

Multivalent metal-sulfur(M-S,where M=Mg,Al,Ca,Zn,Fe,etc,) batteries offer unique opportunities to achieve high specific capacity,elemental abundancy and cost-effectiveness beyond lithium-ion batteries(LIBs).However,the slow diffusion of multivalent-metal ions and the shuttle of soluble polysulfide result in impoverished reversible capacity and limited cycle performance of M S(Mg-S,Al-S,Ca-S,Zn-S,Fe-S,etc.) batteries.It is a necessity to optimize the electrochemical performance,while deepening th...     

Silica sol–gel chemistry: creating materials and architectures for energy generation and storage

There is widespread recognition that the use of energy in the twenty-first century must be sustainable. Because of its extraordinary flexibility, silica sol–gel chemistry offers the opportunity to create the novel materials and architectures which can lead to significant advances in renewable energy and energy storage technologies. In this paper, we review some of the significant contributions of silica sol–gel chemistry to these fields with particular emphasis on electrolytes and separators where sol–gel approaches to functionalization and encapsulation have been of central importance. Examples are presented in the areas of dye-sensitized solar cells, biofuel cells, proton exchange membrane fuel cells, redox flow batteries and electrochemical energy storage. Original work is also included for the sol–gel encapsulation of a room temperature ionic liquid to create a solid state electrolyte for electrochemical capacitors. In view of the critical importance of energy and the versatility of the sol–gel process, we expect the sol–gel field to play an increasingly important role in the development of sustainable energy generation and storage technologies.     

Microencapsulated oleic–capric acid/hexadecane mixture as phase change material for thermal energy storage

Journal of Thermal Analysis and Calorimetry - Thermal energy storage systems provide efficiency in order to have better utilization of energy sources while protecting the environment. Thermal...     

TOF-SIMS investigations on thermally treated copper–molybdenum films on a carbon substrate

Metal-matrix composites are made of materials with different physical and chemical properties. It is possible to change the mechanical, thermal and electrical properties by variation of the mass ratio of the components; therefore, metal-matrix composites have great value for industrial and technological applications. Copper–carbon composites have a good chance to be used as heat sinks for electronic components, which can be explained by their high thermal conductivity, low density and an adjustable coefficient of thermal expansion. On the other hand, the mechanical adhesion of copper and carbon is extremely weak because of their immiscibility and weak chemical interactions. In order to compensate for the low wettability of carbon by copper, a thin molybdenum intermediate layer is used as an adhesion promoter. In this work a time of flight secondary ion mass spectrometry technique was primarily used to detect the carbide formation in the molybdenum and copper layers, depending on different temperature conditions during sputter deposition and annealing afterwards. The CuMo layers were deposited by magnetron sputtering. The adhesion of the samples was determined by a destructive pull-off test. We found that heat treatment mainly modifies the carbide formation in the molybdenum and copper layers.     

Ionic liquid–solid interface and applications in lubrication and energy storage

Room-temperature ionic liquids (ILs) exhibit many attractive properties in proximity to solid surfaces. Primarily, they form well-defined interfacial layers that are tunable — electrically and thermally — as well as being stable — mechanically, electrically, and thermally — over a wide range. Recent investigations have aimed at understanding the molecular structuring of ILs at their interface with solids and in confinement, while in tandem, ILs are used as next-generation lubricants and energy storage materials. The result is a large volume of work that has appeared over the last decade. In this review, the recent literature is presented and future research directions are discussed.     

Copper oxide-modified glassy carbon electrode prepared through copper hexacyanoferrate–G5-PAMAM dendrimer templates as electrocatalyst for carbohydrate and alcohol oxidation

We describe the modification of a glassy carbon electrode by electro-deposition of copper hexacyanoferrate (CuHCF) in the presence of an amine-terminated dendrimer (PAMAM) as a template. The electrode containing the CuHCF template was cycled in alkaline solution to generate a layer of cupric oxide (CuO). The mechanism of the formation of CuO and its electrocatalytic activity were investigated by cyclic voltammetry. Scanning electron microscopy reveals that the CuO prepared by this method has a meso-porous grid-like appearance. The formation of CuO was identified by XPS analysis of the modified electrode. The ability of the CuHCF film towards the electrocatalytic oxidation of carbohydrates and alcohols was detected using cyclic voltammetry. The over-potential required for carbohydrate and alcohol oxidation is lowered by ~400 mV compared to other chemically modified electrodes reported in the literature. Simple methodology has been adopted in this work for the preparation of the catalytically active electrode, and this work also explains the structure directing effect of dendrimer and its influence on the electrocatalytic oxidation of analytes.     

Agar: a natural and environmentally-friendly support composed of copper oxide nanoparticles for the green synthesis of 1,2,3–triazoles

ABSTRACT

A novel, green and cost-effective heterogeneous nanocatalyst was synthesized by supporting copper (I) oxide nanoparticles on magnetic agar (Cu₂O/Agar@Fe₃O₄). Then, it was characterized with multiple techniques, such as scanning electron microscopy and transmission electron microscopy images, energy-dispersive X-ray analysis, Fourier-transform infrared (FT–IR) spectroscopy, thermogravimetric (TG) analysis, X-ray diffraction pattern, vibrating sample magnetometer curve, and inductively coupled plasma analysis. The catalytic activity of the newly designed catalyst was investigated in a one-pot three-component reaction of alkyl halides, sodium azide, and alkynes to obtain 1,4–disubstituted 1,2,3–triazoles in high yields in water–ethanol media. The present catalyst was simply separated from the reaction media by an external magnet and reused at least five subsequent runs without significant activity loss.     

Synthesis and structure of a new polyoxometalate-based inorganic–organic hybrid and application as a chemically bulk-modified electrode

A new Keggin-type polyoxometalate-based inorganic–organic hybrid, [Cu(H₂O)₂(daphen)]₂[SiW₁₂O₄₀]·9H₂O (1) (daphen?=?5,6-diamino-1,10-phenanthroline), was hydrothermally synthesized, and characterized by single-crystal X-ray diffraction, elemental analysis, infrared spectroscopy, fluorescence spectra, and thermal analysis. Single-crystal X-ray diffraction analysis reveals that in 1, [SiW₁₂O₄₀]^4? is a tetradentate ligand with its four terminal oxygens coordinating to four Cu(II)–daphen fragments to form a 2D sheet with (4,4) topology. On the basis of the insolubility of 1 in water and common organic solvent and its reversible multielectron redox processes, 1 was used to fabricate a bulk-modified carbon paste electrode (1-CPE) by direct mixing. Electrochemistry indicated that 1-CPE is stable over hundreds of cycles and possessed electrocatalytic activity toward the reduction reactions of nitrite.     

Fe2O3@[proline]–CuMgAl–LDH: A magnetic bifunctional copper and organocatalyst system for one-pot synthesis of quinolines and 2H-indazoles in green media

A novel magnetic core–shell Fe₂O₃@[proline]–CuMgAl–L(ayered)D(ouble)H(ydroxide) was designed as an efficient bifunctional catalytic system. To this end, Cu (II) was combined with Mg and Al in the LDH structure and l -proline was intercalated between LDH layers in order to perform a straightforward synthesis of quinolines and 2H-indazoles as two important pharmaceutical N-aryl-substituted heterocyclic compounds. In this regard, a facile method was employed through consecutive condensation under a mild conditions in choline azide media, which played the role of a reagent and a solvent to avoid toxic solvents and hazardous azidation reagents. These techniques provided considerable improvement in terms of using green media, reducing starting materials, reaching higher yields and offering a shorter reaction time and lower temperature. In conclusion, it was found that the catalyst could be reused five times with no significant loss of activity.     

Nanostructured Fe2O3–graphene composite as a novel electrode material for supercapacitors

Nanostructured Fe₂O₃–graphene composite was successfully fabricated through a facile solution-based route under mild hydrothermal conditions. Well-crystalline Fe₂O₃ nanoparticles with 30–60?nm in size are highly encapsulated in graphene nanosheet matrix, as demonstrated by various characterization techniques. As electrode materials for supercapacitors, the as-obtained Fe₂O₃–graphene nanocomposite exhibits large specific capacitance (151.8?F?g^?1 at 1?A?g^?1), good rate capability (120?F?g^?1 at 6?A?g^?1), and excellent cyclability. The significantly enhanced electrochemical performance compared with pure graphene and Fe₂O₃ nanoparticles may be attributed to the positive synergetic effect between Fe₂O₃ and graphene. In virtue of their superior electrochemical performance, they will be promising electrode materials for high-performance supercapacitors applications.     

Solid-state lithium-ion batteries for grid energy storage:opportunities and challenges

The energy crisis and environmental pollution drive more attention to the development and utilization of renewable energy.Considering the capricious nature of renewable energy resource, it has difficulty supplying electricity directly to consumers stably and efficiently, which calls for energy storage systems to collect energy and release electricity at peak periods. Due to their flexible power and energy, quick response, and high energy conversion efficiency, lithium-ion batteries stand out amo...     

Functionalized graphene–polyaniline nanocomposite as electrode material for asymmetric supercapacitors

Journal of Solid State Electrochemistry - A polyaniline/sulfonated graphene (PANI/SG) nanostructure was synthesized as electrode material for an asymmetric supercapacitor via a novel in situ...     

Unique NiFe–NiCoO_2 hollow polyhedron as bifunctional electrocatalysts for water splitting

It is of significance to design of stable and cost-effective electrocatalyst for water splitting with high efficiency in an alkaline medium.The major obstacles for practical application of water splitting devices are lack of high-efficiency and low-cost electrocatalysts with low overpotential for both HER and OER.In this paper,we report a NiFe alloy decorated NiCoO_2 hollow polyhedron(denoted as Ni Fe–Ni Co O_2)by using[NiFe(CN)_6]~- intercalated NiCo–LDH as precursor.As evidenced by the electrochemical active surface area,the resultant Ni Fe–Ni Co O_2 composite shows unique hollow nanostructure,which can not only provide abundant mass transport channels,but also increase the contact area of the NiFe–Ni Co O_2 material with the electrolyte.The overpotential(η)demand is 286 mV for OER and 102 mV for HER at the current density of 10 mA/cm~2 in an alkaline medium of 1 M KOH for the NiFe/NiCoO_2 composite.This work provides a new pathway for preparation of the highly efficient bifunctional electrocatalysts for water splitting.     

Crown daisy leaf waste–derived carbon dots: A simple and green fluorescent probe for copper ion

In this paper, N-doped carbon quantum dots (N-CDs) were fabricated using crown daisy leaves, a kitchen waste, as carbon source. The synthesized N-CDs possessed abundant surface functional groups, such as hydroxyl, carboxyl, and amino groups, and had good dispersibility in water. Because of the special fluorescence quenching property toward Cu²⁺, the synthesized N-CDs can be exploited as an effective label-free fluorescent probe for Cu²⁺ determination. The possible fluorescence sensing mechanism considered the selective coordination interaction between Cu²⁺ ion and the hydroxyl, carboxyl, and amino groups of the N-CDs. The control experiments also showed that the N-doped aromatic C–N heterocycle structure played a crucial role in selective sensing of Cu²⁺. The decrease in fluorescence efficiencies was linearly related with the Cu²⁺ concentrations in the range of 10.0nM to 120.0nM, with a response limit of 1.0nM. The prepared probe was also applied for Cu²⁺ determination in real river water.     

Simple PVC–PPy electrode for pH measurement and titrations

Cobaltabis(dicarbollide) [3,3'-Co(1,2-C2B9H11)](-)-doped polypyrrole (PPy) films have been prepared galvanostatically on glassy carbon electrodes in acetonitrile solution. The potential response behavior of the film of this new material has been investigated in some common pH buffers and in acid-base titrations. The potentiometric characteristics of the resulting films are indicative of a quasi-Nernstian response (approximately 50 mV/pH unit), a linearity range from pH 12 to 3 and correlation coefficients (r2) of approximately 0.98. The electrode is suitable for pH measurements and for monoprotic titrations of strong alkalis with strong acids, and weak bases with strong acids, but the long response time hinders the use of this electrode for multiprotic titrations. The time response has been dramatically improved by reducing the film thickness by using the template effect of a non-conducting polymer (PVC) cast over the graphite surface before PPy deposition. PPy polymerization occurs in the free channels of PVC leading to the formation of PPy wires. The morphological change of PPy does not affect the slope or linearity range. The response of the PVC-PPy electrochemical sensor is rapid and the sensor is easy to prepare, at low cost, and its performance is comparable with that of commercial glass electrodes.     

Aptamer-based electrochemical assay of 17β-estradiol using a glassy carbon electrode modified with copper sulfide nanosheets and gold nanoparticles,and applying enzyme-based signal amplification

Microchimica Acta - We have developed an electrochemical method for the determination of 17β-estradiol. A glassy carbon electrode was modified with a composite made from copper sulfide...     

Platinum electrode coated with a bentonite–carbon composite as an environmental sensor for detection of lead

A Pt wire coated with a bentonite–carbon composite in a poly(vinyl chloride) membrane was used for detection of lead. The sensor has a Nernstian slope of 29.42±0.50 mV per decade over a wide range of concentration, 1.0×10⁻⁷ to 1.0×10⁻³ mol L⁻¹ Pb(NO₃)₂. The detection limit is 5.0×10⁻⁸ mol L⁻¹ Pb(NO₃)₂ and the electrode is applicable in the pH range 3.0–6.7. It has a response time of approximately 10 s and can be used at least for three months. The electrode has good selectivity relative to nineteen other metal ions. The practical analytical utility of the electrode is demonstrated by measurement of Pb(II) in industrial waste and river water samples.     

Mechanical and dielectric behavior of poly(vinylidene)–poly(arylene ether nitrile) composites as film capacitors for energy storage applications

Novel polymer composites PEN/PVDF were prepared from poly(arylene ether nitrile) (PEN) and poly(vinylidene fluoride) (PVDF) via solution mixing. Due to the toughening effect of PVDF, PEN/PVDF blends with 5 wt % PVDF exhibit higher tensile strength (106 MPa) and breaking elongation (8.09%) than pure PEN does. Because of introduction of PVDF and interfacial polarization, the dielectric constant of PEN/PVDF blends at 1 kHz and room temperature increases from 3.3 to 4.5 with increasing content of PVDF. The dissipation factor (tanδ) of PEN/PVDF blends is relatively low (<0.04) in a very wide frequency range from 250 Hz to 100 kHz. The PEN/PVDF blends show certain piezoelectric behavior (d ₃₃ from 0.9 to 1 pC/N) due to the contribution of PVDF. After polarization, the piezoelectric coefficient d ₃₃ somewhat increases. The results suggest that PEN/PVDF blends will have potential application in electronic information fields, especially in film capacitors.     

Synthesis and thermal properties of poly(styrene-co-acrylonitrile)-graft-polyethylene glycol copolymers as novel solid–solid phase change materials for thermal energy storage

A novel poly(styrene-co-acrylonitrile)-graft-polyethylene glycol(SAN-g-PEG) copolymer was synthesized as new solid–solid phase change materials(SSPCMs) by grafting PEG to the main chain of poly(styrene-co-acrylonitrile). The chemical structure of the SAN-g-PEG was confirmed by the Fourier transform infrared(FT-IR) and proton nuclear magnetic resonance(1H NMR) spectroscopy techniques. The thermal energy storage properties and the storage durability of the SAN-g-PEG were investigated by differential scanning calorimetry(DSC). The SAN-g-PEG was endowed with the solid–solid phase transition temperatures within the range of 23–36 8C and the latent heat enthalpy ranged from 66.8 k J/kg to 68.3 k J/kg. Thermal cycling tests revealed that the SAN-g-PEG kept great heat storage durability after 1000 thermal cycles. The thermal stability was evaluated by a thermal gravity analysis(TGA), and the initial decomposition temperature(Td) of SAN-g-PEG is 350 8C, which proves that the SAN-g-PEG possessed good thermal stability.