Solid-state synthesis of nitrogen-doped graphitic nanotubes with outstanding electrochemical properties

Synthesis of new anodes is crucial for commercialization of rechargeable potassium-ion batteries (PIBs). In this work, the nitrogen-doped graphitic nanotubes (NGTs) were synthesized by solid-state reaction method. The microstructural characterization of synthesized NGTs revealed the presence of many active sites (provided by N-doping i.e. N_p and N_g) and tubular channels for the K⁺ ion transport. The NGTs electrode was tested against potassium metal in the presence of carbonate based electrolytes. The NGTs revealed the maximum reversible capacity of 220 mA h g^?1 at 20 mA g^?1 current density. Furthermore, the cycle stability of NGTs was confirmed by cycling it for 200 times at the current density of 100 mA g^?1, where specific capacity of 81.2 mA h g^?1 was retained. The excellent electrochemical properties (rate capability) and fast synthesis of NGTs highlights its possibility to be used against post-lithium metal anodes in near future.     

Electrochemical synthesis of a novel sulfonated polyaniline and its electrochemical properties

A novel N-substituted aniline, N-(4-sulfonicbutyryl)aniline was synthesized and subsequently to be electropolymerized to yield a new conductive polymer, poly(N-(4-sulfonicbutyryl)aniline). X-ray photoelectron spectrum (XPS) of the polymer film was examined to propose the polymer molecular structure. The sulfonated polyaniline was also characterized by ¹H NMR, TGA, DTA, FTIR, and UV–vis spectra. The sulfonated polyaniline showed high conductivity in neutral aqueous solutions, which is two orders of magnitude higher than that of poly(N-acetylaniline) (PNAANI).     

Flexible carbon nanotube/polyaniline paper-like films and their enhanced electrochemical properties

The carbon nanotube/polyaniline (CNT/PANI) composites have important potential applications as the electrodes in energy storage devices for their attractive electrochemical properties. In this work, we report a novel method to prepare the interesting paper-like CNT/PANI composites by using the CNT network as the template. Compared with the conventional brittle CNT/PANI composites, these paper-like composites were much thin and flexible. This work demonstrates a new approach, which may transform a brittle polymer into flexible films. Meanwhile, these film electrodes showed much superior electrochemical performance such as higher specific capacitance, lower internal resistivity, and more stability under different current loads. These paper-like composite electrodes have promising applications in new kinds of energy storage devices.     

Electrochemical synthesis of Cu-containing polyheteroarylenes and study of their catalytic properties

Method of electrochemical synthesis of new Cu-containing polyheteroarylenes that have biquinolyl units in their main chain is developed on the base of the soluble anode technique. The study of electrochemical properties of thus obtained Cu-containing polymer and the corresponding monomer complex revealed existence of two types of coordination environment: (1) copper Cu(I) in the tetrahedral surrounding of two biquinolyl ligands and (2) copper Cu(I) bound with only one biquinolyl fragment. The complexes with one biquinolyl polymer ligand showed high activity as catalysts for O₂ reduction in the presence of hydroquinone that is converted to quinone in the course of the reaction.     

Functional mesoporous carbon nanotubes and their integration in situ with metal nanocrystals for enhanced electrochemical performances

Functional mesoporous carbon nanotubes (MCNTs) and their integration in situ with Pt nanocrystals (Pt/MCNTs) have been designed and successfully developed via a facile route, which exhibited enhanced performances in energy storage and conversion applications.     

An unusual one step synthesis of acetylenes

Substituted nitrostyrenes on reaction with H₂O₂/NEt₃ give 1,2 diaryl acetylenes in ~ 30 % yield.     

Microwave-assisted one step high-throughput synthesis of benzimidazoles

One-pot synthesis of benzimidazoles from diamines and carboxylic acids was developed under microwave irradiation condition, which provided a practical and efficient method for high-throughput synthesis of this important class of heterocyclic compounds.     

Carbon-coated manganese dioxide nanoparticles and their enhanced electrochemical properties for zinc-ion battery applications

In this study, we report the cost-effective and simple synthesis of carbon-coated α-MnO_2nanoparticles(α-MnO_2@C) for use as cathodes of aqueous zinc-ion batteries(ZIBs) for the first time. α-MnO_2@C was prepared via a gel formation, using maleic acid(C_4H_4O_4) as the carbon source, followed by annealing at low temperature of 270 °C. A uniform carbon network among the α-MnO_2 nanoparticles was observed by transmission electron microscopy. When tested in a zinc cell, the α-MnO_2@C exhibited a high initial discharge capacity of 272 m Ah/g under 66 m A/g current density compared to 213 m Ah/g, at the same current density, displayed by the pristine sample. Further, α-MnO_2@C demonstrated superior cycleability compared to the pristine samples. This study may pave the way for the utilizing carbon-coated MnO_2 electrodes for aqueous ZIB applications and thereby contribute to realizing high performance eco-friendly batteries.     

Novel one step hydrothermal synthesis of TiO2/WO3 nanocomposites with enhanced photocatalytic activity

A novel and simple one step hydrothermal process is used to prepare TiO(2)/WO(3) nanocomposites, in which WO(3) and TiO(2) are present in hexagonal and anatase crystalline forms, respectively, and have enhanced photocatalytic activity towards trichloroethylene degradation in the gas phase.     

One-step hydrothermal synthesis of flower-like SnO2/carbon nanotubes composite and its electrochemical properties

In this work, flower-like SnO₂/carbon nanotubes (CNTs) composite was synthesized by one-step hydrothermal method for high-capacity lithium storage. The microstructures of products were characterized by XRD, FESEM and TEM. The electrochemical performance of the flower-like SnO₂/CNTs composite was measured by cyclic voltammetry and galvanostatic charge/discharge cycling. The results show that the flower-like SnO₂/CNTs composite displays superior Li-battery performance with large reversible capacity and high rate capability. The first discharge and charge capacities are 1,230 and 842 mAh g^?1, respectively. After 40 cycles, the reversible discharge capacity is still maintained at 577 mAh g^?1 at the current densities of 50, 100 and 500 mA g^?1, indicating that it’s a promising anode material for high performance lithium-ion batteries.     

A novel convenient one step pyrimidine synthesis

A new method for the preparation of pyrimidines by condensation of β-dicarbonyl compounds, ammonium salts and carbonyl containing substances has been developed.     

Vanadium-oxide nanotubes: Synthesis and template-related electrochemical properties

The electrochemistry of mixed-valent-containing vanadium-oxide nanotubes (VO_x-NTs) is first reported. Using dodecylamine and hexadecylamine as templates, two kinds of VO_x-NTs were synthesized and characterized. Both VO_x-NTs contain V₂O₃, VO₂ and V₂O₅ species. Dodecylamine-templated VO_x-NTs (C₁₂-VO_x-NTs) are much more stable than hexadecylamine-templated VO_x-NTs (C₁₆-VO_x-NTs). C₁₂-VO_x-NTs demonstrate stable redox behavior at ∼−0.2 V, which is arising from the electrochemical transfer between V(III) and V(IV), whereas C₁₆-VO_x-NTs exhibit unstable and weak redox peaks. In both cases, the reduction reaction of V(V)–V(IV) is never observed. The oxidation peak for V(IV) appeared only after a relatively long time immersion, suggesting that some small molecules such as water intercalate into the layered nanostructures before the electrochemical reaction. The difference may be an origin of the different template-induced the electroactivity of vanadium-oxide species in the nanotube-microenvironment.     

一步法合成二甲醚整体式催化剂的制备及反应性能研究

以蜂窝陶瓷为载体、γ-Al₂O₃为惰性涂层、C301/HZSM-5为活性组分制备出一种整体式合成二甲醚催化剂。BET、XRD和SEM分析结果表明,活性组分均匀负载在载体表面上,催化剂具有良好的结构和织构特点。在固定床反应器中考察了整体式催化剂上CO加氢一步法合成二甲醚的反应性能,并与C301/HZSM-5颗粒（粉末）催化剂进行了比较。在温度260℃、压力4.0MPa、合成气空速1500mL/(g·h)的条件下,整体式催化剂上CO转化率达到79.62%,二甲醚选择性为70.58%,分别比C301/HZSM-5颗粒催化剂高出7.78%和9.44%。100h的稳定性实验结果表明,整体式催化剂可以保持较高的活性和选择性,而颗粒状催化剂的活性有明显的下降。
     

Surface modification of single-walled carbon nanotubes by functional nitrogen-containing groups and study of their properties

Treatment of single-walled carbon nanotubes (SWCNT) in a gaseous 40%NH₃–1%С₂Н₂–C₂H₄ mixture at 600 and 700°С led to “nitrogen-containing carbon coating–single-wall carbon nanotubes” composites. Single-walled carbon nanotubes after etching in aqua regia (SWCNTetch) and doped with nitrogen (N-SWCNT) were studied by XPS, electron microscopy, and IR spectroscopy. It was found that the initial SWCNTetch surface contains various oxygen-containing functional groups. Treatment of SWCNTetch in a 40%NH₃–1%С₂Н₂–C2H₄ mixture led to the formation of a thin carbon coating on the carbon nanotube surface due to polymerization and condensation of hydrocarbons. After treatment at 600°C, the formation of nitrogen-containing functional groups is insignificant; however, when the treatment temperature is increased to 700°C, the nitrogen content reaches 0.5 at % of the weight of the N-SWCNT sample.     

Two step, hydrolytic-solvothermal synthesis of redispersible titania nanocrystals and their gas-sensing properties

A titanium chloromethoxide solution was prepared by reacting TiCl₄ with methanol, followed by water addition. The starting solutions were characterized by Fourier Transform Infrared (FTIR) spectroscopy, evidencing that the in situ generated water results in early hydrolysis of the chloroalkoxide. The solution was reacted with molten dodecylamine at room temperature, obtaining a white slurry of amorphous titania nanoparticles. Stable, redispersible TiO₂ nanocrystals could be prepared by subsequent solvothermal treatment in oleic acid at 250???C. The use of oleic acid was essential for obtaining crystalline structures, while other surfactants prevented crystallization. The nanocrystals were characterized by X-ray Diffraction and Transmission Electron Microscopy, confirming the formation of anatase TiO₂ nanocrystals with a mean size of 3.3?nm. The TiO₂ nanocrystals were used for fabricating gas-sensing devices, which were tested towards ethanol vapors. The initial small size of the nanocrystals, and the limited size growth during the high-temperature sensor operation, result in remarkable sensing performances if compared with bulk titania sensors.     

Room-temperature synthesis of pompon-like ZnO hierarchical structures and their enhanced photocatalytic properties

In this paper, an efficient and simple route combined with a subsequent calcining process to synthesize pompon-like ZnO microstructures at room temperature (25 °C) has been developed. The samples were intensively investigated by SEM, TEM, HRTEM, and XRD. The results indicate that the well-crystallized pompon-like ZnO is assembled by interlaced nanoplates with uniform thickness of about 50 nm. The photocatalytic trials confirm that the pompon-like ZnO exhibits excellent degradation efficiency under UV light. Moreover, the as-prepared ZnO samples show superior durability and stability after six photodegradation cycling runs. Finally, a mechanism was proposed to elucidate the photodegradation reaction of the pompon-like ZnO.     

A novel one step synthesis of a dihydropentalene

1,4-Dipyrrolidinocyclohexa-1, 3-diene 4 reacts with dimethyl acetylenedicarboxylate i an unexpected manner to produce the substituted dihydropentalene 6.     

Electrochemical synthesis of metal and semimetal nanotube-nanowire heterojunctions and their electronic transport properties

Metal and semimetal nanotube-nanowire heterojunction arrays have been achieved by sequential electrochemical-deposition inside the nanochannels of anodic aluminium oxide template with a layer of Au thin enough to leave the pores open.     

Microwave-mediated one step synthesis of tri- and tetracyclic heterocyclic molecules

Abstract

Tricyclic and tetracyclic compounds related to vasicine and batracyclin, respectively, have been synthesized via condensation of dicarboxylic acids (aliphatic acid, homophthalic acid, and aromatic acid) with diamines (aliphatic, aminobenzyl amine, and aromatic amine) under solvent-free condition.     

Efficient silver modification of TiO2 nanotubes with enhanced photocatalytic activity

In this paper, Ag(CH₃NH₂)₂⁺, Ag(NH₃)₂⁺ and Ag⁺ with different radii have been used as silver sources to find out the distribution of Ag ions on the H-TNT surface, which is critical to the final performance. The influence of this distribution on visible photocatalytic activity is further studied. The results indicate that, when Ag⁺ used as silver source with low concentration, these small sized silver ions mainly distribute on interlayer spacing of H-TNT. After heat-treatment and photo-reduction, the generated silver nanoparticles uniformly embed in the anatase TiO₂ nanotube walls, and bring large interfacial area between Ag particles and TiO₂ nanotubes. The separation effect of photogenerated electron-hole pair in TiO₂ is enhanced by Ag particles, and achieves the best at 0.15 g/L, much higher than P25, TiO₂/0, Ag-N@TiO₂ and Ag-C-N@TiO₂. This paper provides new ideas for the modification of TiO₂ nanotubes.