Two-dimensional cobalt–manganese binary metal oxide porous nanosheets for high-performance supercapacitors

Journal of Solid State Electrochemistry - Two-dimensional cobalt–manganese binary metal oxides (Co1.5Mn1.5O4) porous nanosheets have been successfully synthetized via a simple liquid phase...     

One-pot synthesis of CoO–ZnO/rGO supported on Ni foam for high-performance hybrid supercapacitor with greatly enhanced cycling stability

The high specific capacitance along with good cycling stability are crucial for practical applications of supercapacitors,which always demands high-performance and stable electrode materials.In this work,we report a series of ternary composites of CoO-ZnO with different fractions of reduced graphene oxide(rGO) synthesized by in-situ growth on nickel foam,named as CZG-1,2 and 3,respectively.This sort of binder-free electrodes presents excellent electrochemical properties as well as large capacitance due to their low electrical resistance and high oxygen vacancies.Particularly,the sample of CZG-2(CoO-ZnO/rGO 20 mg) in a nanoreticular structure shows the best electrochemical performance with a maximum specific capacitance of 1951.8 F/g(216.9 mAh/g) at a current intensity of 1 A/g.The CZG-2-based hybrid supercapacitor delivers a high energy density up to 45.9 Wh/kg at a high power density of 800 W/kg,and kept the capacitance retention of 90.1% over 5000 charge-discharge cycles.     

Non-hydrolytic sol–gel synthesis of tantalum sulfides

Non-hydrolytic sol–gel synthesis provides a low temperature solution based approach to solid-state materials. In this work, reactions of TaX₅ (X = F, Cl, Br, I) with the thio-ethers di-tert-butylsulfide and hexamethyldisilathiane were carried out in chloroform or acetonitrile. The influence of synthetic parameters such as temperature, reaction time, starting sulfur to tantalum ratio, and solvent volume were explored, and optimized conditions for the preparation of phase pure crystalline TaS₂ were established. Amorphous powders were recovered for most of the samples, but crystalline 1T- and 3R-TaS₂ modifications could be selectively prepared by heat treatments of the as-recovered precursors at 700 and 800 °C, respectively. The crystallite sizes could be adjusted by tuning the starting sulfur to tantalum ratios, and by choice of solvent. For specific conditions, nanocrystalline 1T-TaS₂ was directly recovered from solution. To our knowledge, this is the first time that crystalline TaS₂ was directly obtained from low temperature solution based routes.     

One-pot synthesis of graphene–cuprous oxide composite with enhanced photocatalytic activity

In this paper, graphene–cuprous oxide (G–Cu₂O) composites were synthesized at room temperature using graphene oxide (GO) as two-dimensional support. From Zeta potential analysis, the surface charge of G–Cu₂O composites altered from positive to negative, which favors the adsorption and photodegradation of positively charged dyes. Compared with Cu₂O under similar synthesis condition, the G–Cu₂O composites demonstrated improved photodegradation activity for methylene blue (MB) dye under visible light. Controlled experiments indicated that the G–Cu₂O composite synthesized with 80 mg GO in the reaction system possessed more negative Zeta potential, highest specific surface area and thus presented the highest photocatalytic activity. Electrons mechanism for the improved photocatalytic performance of G–Cu₂O composite was proposed in the degradation of MB.     

One-pot synthesis of α-phenylsulfinyl ketones by reaction of phenyl benzenethiosulfinate with enolate anions,and synthesis of sulfoxides and sulfides by its reaction with Grignard reagents

Phenyl benzenethiosulfinate reacts with enolate anions derived from ketones to give α-phenylsulfinyl ketones directly, together with minor amounts of α-phenylsulfanyl ketones. These are easily separated by forming the water-soluble sodium salts of the sulfinyl compounds. Grignard reagents also react with phenyl benzenethiosulfinate, to give mixtures of sulfoxides and sulfides.     

Shapeable carbon fiber networks with hierarchical porous structure for high-performance Zn–I;batteries

Aqueous rechargeable zinc-iodine batteries(ZIBs)emerging as a promising energy storage alternative have attracted considerable attention.However,ZIBs still suffer from the severe shuttle effect of polyiodide and poor reversibility,leading to the poor cycling lifetime and potential safety issues.Herein,the assembly of Al-based metal-organic frameworks(Al-MOFs)in the presence of polyacrylonitrile(PAN)via electrospinning technique enables the formation of Al-MOF/PAN fibers.With the subsequent pyrolysis,the hierarchical porous carbon fibers with nitrogen doping(NPCNFs)are prepared for loading iodine.Benefiting from the confinement effect of the highly porous carbon network and the nitrogen doping,the self-supported carbon nanofiber electrode is capable of inhibiting the shuttle effect of polyiodide species.Especially,the in-situ Raman spectroscopy reveals the reversible two-step conversion reaction between iodine and polyiodide,which enables the best cycling stability for over 6,000 cycles with negligible capacity.This work demonstrates an efficient approach to regulating the porous structure and surface properties in the design of advanced iodine electrodes for high-performance ZIBs.     

Activated hierarchical porous carbon@π-conjugated polymer composite as cathode for high-performance lithium storage

Organic compounds become promising candidates for cathodes of rechargeable lithium battery (RLB) due to the high theoretical capacity and improved safety. However, they exhibit low conductivity and easy dissolution in electrolyte, which leads to the low utilization of active materials and poor cycling stability of RLBs. Here, we synthesize a novel composite of activated hierarchical porous carbon supporting poly(1,5-diamino-anthraquinone) (aHPC@PDAA), using Ce(SO₄)₂ as oxidant and naphthalenesulfonic acid (NSA) as soft template for PDAA. The as-synthesized composite exhibits uniformly nanoporous structure with nano-sized PDAA particles distributed homogenously inside and outside of pores. The aHPC@PDAA cathode for RLBs achieves high electrochemical performance with a discharge capacity as much as 250 mAh g^?1 at the current density of 100 mA g^?1, which still maintains 176 mAh g^?1 after 2000 charging-discharging cycles.     

One-pot enyne ring-closing metathesis–Diels–Alder reactions for the synthesis of polycyclic sulfamides

Ring-closing metathesis (RCM) and sequential Yb(OTf)₃ promoted Diels–Alder reactions of sulfamide-linked enynes proceeded selectively in one-pot to afford a series of bicyclic and tricyclic sulfamides. Excellent levels of diastereoselectivity are observed for the cycloaddition step, with only the endo-adducts being isolated. The protocol was further extended to incorporate a one-pot RCM–cross metathesis (CM)–Diels–Alder sequence, permitting rapid access to high levels of molecular complexity from simple and easily accessible precursors.     

A strategic way of high-performance energy storage device development with environmentally viable ‘‘Water-in-salt” electrolytes

Development of cost-effective and environmental friendly energy storage devices(ESDs) has attracted widespread attention in recent scenario of energy research.Recently,the environmentally viable "water-in-salt"(WiS) electrolytes has received significant interest for the development of advanced high performance ESDs.The WiS electrolyte exhibits wide electrochemical stability window(ESW),highsafety,non-flammability and superior electrochemical performance compared to the conventional "salt-in-wate...     

Rapid synthesis of aryl sulfides through metal-free C–S coupling of thioalcohols with diaryliodonium salts

An efficient, general, and highly selective method for the synthesis of aryl sulfides has been developed through metal-free, direct C–S coupling from thioalcohols and diaryliodonium salts. Significantly, the reaction took only 10 min to complete and produced high yields at room temperature. Thus, this methodology proves its value as a versatile synthetic choice for a broad range of aryl sulfides, producing good to excellent yields.     

One-pot synthesis of an unusual manganese–lanthanide–ferrocene cluster: A combination of d-, f-metals and an organometallic fragment

Reaction of the preformed cluster [Mn₆O₂(Piv)₁₀(4-Me-py)_2.5(PivH)_1.5] with Nd(NO₃)₃.6H₂O, N-butyldiethanolamine (bdeaH₂) and ferrocene-1,1′-dicarboxylic acid (fcdcH₂) resulted in the formation of the first 3d–4f complex incorporating organometallic ferrocene [Mn₄Nd₄(OH)₄(fcdc)₂(Piv)₈(bdea)₄]·H₂O; we report the X-ray structure and preliminary magnetic studies of this high-nuclearity cluster.     

Sol–gel synthesis of porous titania fibers by electro-spinning for water purification

In this study, porous ceramic fibers were prepared by the sol–gel-assisted electro-spinning process using colloidal dispersion of complex fluids for the application of phtotocatalysts. First, polystyrene nanospheres were synthesized by dispersion polymerization as sacrificial templates for porous fibers. Then, the mixture of polyvinylpyrrolidone and the ceramic precursor with the polymeric nanospheres was prepared as the spinning solution and self-organized by electro-spinning, followed by calcination of the electrospun composite fibers. The morphologies of the porous fibers could be controlled according to the size of the templates and the amount of the ceramic precursor. The nano-structure of the pores in the fibrous materials could also be adjusted as open or closed cavities with various potential applications. As a demonstrative application, the macroporous titania fibers could be utilized as photocatalysts for the removal of organic dyes dissolved in water. A better photocatalytic activity of the macroporous fibers with 700-nm pore diameter was observed compared to the result of nonporous titania fibers due to the increased porosity. Collectively, the macroporous ceramic fibers were found to be efficient functional materials to prepare the unique nano-structured materials other than simple nonporous fibers.     

FT-IR and thermal studies of iron–nickel–manganese ternary levo-tartrate crystals

Several metallic tartrates deserve special attention due to their various applications. In the present investigation, mixed tartrate crystals of three different metals are reported. Using single diffusion gel growth technique, iron–nickel–manganese (Fe–Ni–Mn) ternary levo-tartrate compound crystals were grown with different concentrations. Spherulitic crystals with different coloration were obtained for various concentrations of metals. The concentrations of metals were determined by EDAX. The presence of functional groups was confirmed using Fourier transform infrared (FT-IR) spectroscopy. The powder XRD study suggested that the crystals belong to the orthorhombic system. The thermal stability of all the samples was studied from room temperature to 900 °C. It was found that the composition of the crystal affects the dehydration and decomposition behaviors. The results are discussed.     

Mechanoelectrochemical synthesis and properties of porous nano-Ti–6Al–4V alloy with hydroxyapatite layer for biomedical applications

Formation of porous morphology in nanocrystalline mechanically alloyed and electrochemically etched Ti–6Al–4V biomedical alloy was investigated. The alloy was electrochemically etched in a mixture of H₃PO₄ and HF. The electrochemical etching results in broad range from micro(nano)-macropores formation in the surface layer, with diameter in the range of 3 nm–60 µm. On the etched surface hydroxyapatite was electrochemically deposited by using 0.042 M Ca(NO₃)₂ + 0.025 (NH₄)₂HPO₄ + 0.1M HCl electrolyte. In this way bioactive surface was prepared. The pores in the surface acts as anchors for the hydroxyapatite, which grows inside them. Due to the porous morphology, the etched as well as HA deposited surface is promising for hard tissue implant applications. The nanocrystalline alloy has a nanohardness and Young modulus in the range of 993–1275 HV and 137–162 GPa, respectively.     

Extended investigation of LiOH–LiBr binary system for high-temperature thermal energy storage applications

Journal of Thermal Analysis and Calorimetry - LiOH–LiBr binary system is thoroughly investigated by means of DSC and XRD experimental analysis. Observed discrepancies compared to previous...     

One-pot synthesis of organo-silica hybrids with high thermal properties via a simple sol–gel process

Journal of Thermal Analysis and Calorimetry - Organic–inorganic hybrid composites have received much attention of scientists in the recent years due to the notable improvement of thermal...     

One-pot co-precipitation of copper–manganese–zinc oxide catalysts for the oxidation of CO and SO2 in the presence of ultrasonic irradiation

Research on Chemical Intermediates - This paper studies the effect of addition of Zn and ultrasound-assisted co-precipitation on Cu-Mn oxide catalysts for the oxidation of CO. Cu-Mn-Zn oxide...     

One-pot synthesis of a rose-like Pd–Fe3O4 nanocatalyst for Sonogashira coupling reactions

A one-pot synthesis of rose-like Pd–Fe₃O₄ nanocomposites via the controlled thermal decomposition of Fe(CO)₅ and reduction of Pd(OAc)₂ is reported. This rose-like Pd–Fe₃O₄ composite structure has a high surface area owing to the individual Pd–Fe₃O₄ nanosheets, which imparted a high catalytic activity for Sonogashira coupling reactions. Moreover, the catalyst also demonstrated magnetic recyclability.     

The preparation and properties of “porous silicon–nickel ferrite” nanoheterocomposites for gas detectors

This paper discusses the preparation and properties of gas detectors based on “porous silicon–nickel ferrite” nanocomposites. Impedance spectroscopy was used to measure sensitivity to ethanol and isopropanol vapours in the presence of an alternating electric field. The results were interpreted with the help of an equivalent electrical circuit. In the analysis of the resistive–capacitive properties in the equivalent circuit a constant phase element was used.