三维钒氧化合物的水热合成与表征

利用水热合成的方法,制备了三维钒氧化合物H3V3O9,X射线衍射实验确定了其结构,结果显示,晶体为单斜晶系,P1空间群,晶胞参数为a=4.9980(10)nm,b=8.4188(17)nm,c=7.8614(16)nm,α=90.00°,β=96.40(3)°,γ=90.00°,Z=328.72(11),D=2.999,F(000)=282,R1=0.023 0,wR2=0.0678.通过IR光谱和热重分析对化合物进行了表征.     

Hydrothermal synthesis and crystal structure of a layered vanadium oxide with an interlayer metal coordination complex: [Co(phen)3][V10O26]·H2O

A novel compound, [Co(phen)₃][V₁₀O₂₆]·H₂O, was hydrothermally synthesized and characterized by single-crystal X-ray diffraction. This compound crystallizes in the orthorhombic space group Ccca with a=13.447(3), b=29.936(6), c=23.252(5) Å, V=9360(3) Å³, Z=8 and R=0.0285. Data were collected on a Rigaku R-AXIS RAPID IP diffractometer at 293 K in the range of 1.36<θ<24.99°. The structure of the compound consists of vanadium oxide layers, which are built up from the infinite VO₄ chains by corners and edges sharing. The [Co(phen)₃]²⁺ complexes occupy the interlayer space and contact each other via π−π stacking interactions of the phen groups to form infinite one-dimensional chains.     

Redox interaction of sulfonated polyaniline with vanadium(IV) in water

The redox interaction between poly(2-methoxyaniline-5-sulfonic acid) (PMAS, emeraldine form) and V(IV) readily occurred to produce the PMAS(red) and V(V) species in an aqueous solution. Notably, molecular oxygen was able to reoxidize PMAS(red) to form the catalytic redox cycle. This redox interaction was effectively observed in basic conditions rather than in acidic ones.     

Layer-by-layer composite films of polyaniline and vanadium pentoxide sol gels studied by electrochemical surface plasmon spectroscopy

Electroactive multilayer films of polyaniline (PAni) and vanadium pentoxide (V₂O₅) sol-gels were prepared on gold surfaces by means of the layer-by-layer (LBL) method. The stepwise buildup and the optoelectrochemical behaviour of the composite films were investigated in-situ by electrochemical surface plasmon spectroscopy (ESPS). A thickness increment of 2.3 nm per deposited bilayer was obtained by modelling the surface plasmon spectra. The composite multilayer films display charging-discharging characteristics similar to a bare vanadium pentoxide xerogel network along with an optoelectrochemical response which is dominated by the conducting polymer component. Electrochemical impedance spectroscopy (EIS) experiments confirm the findings from ESPS with regard to the presence of different conductive states of the composite.     

Spectroscopic characterization of the structural changes of polyaniline nanofibers after heating

The thermal behavior of PANI nanofibers doped with β-naphthalenesulfonic acid (β-NSA) was investigated and their morphological and structural changes after heating were monitored by SEM, XRD and Raman techniques, respectively. By using electron-scanning microscopy it is possible to verify that the nanofiber morphology is stable and no polymer degradation is observed in thermogravimetric (TG) data up to 200 °C. Nevertheless, the heating promotes the formation of cross-linking structures (phenazine and/or oxazine-like rings), that is clearly demonstrated by the presence of bands at ca. 578, 1398, and 1644 cm⁻¹ in resonance Raman spectra of heated PANI-NSA samples. The most important consequence of the formation of cross-linking structures in PANI-NSA samples is that these samples retain their nanofiber morphology upon HCl doping in contrast to PANI-NSA nanofibers without heating.     

Facile synthesis of vanadium oxide microspheres for lithium-ion battery cathodes

A simple and versatile method for preparation of non-solid and solid V₂O₅ microspheres is developed. Non-solid and solid V₂O₅ microspheres can be controllably prepared via adjusting the mixed solvent volume ratio and reaction time at low temperature. Solid V₂O₅ microspheres display higher discharge capacity and better cycling performance than non-solid V₂O₅ microspheres as a cathode material for lithium-ion batteries, which is ascribed to smaller charge transfer and diffusion resistance.     

Facile synthesis of multifunctional multiwalled carbon nanotubes/Fe3O4 nanoparticles/polyaniline composite nanotubes

With an average diameter of 100-150 nm, composite nanotubes of polyaniline (PANI)/multiwalled carbon nanotubes (MWNTs) containing Fe₃O₄ nanoparticles (NPs) were synthesized by a two-step method. First, we synthesized monodispersed Fe₃O₄ NPs (d=17.6 nm, σ=1.92 nm) on the surface of MWNTs and then decorated the nanocomposites with a PANI layer via a self-assembly method. SEM and TEM images indicated that the obtained samples had the morphologies of nanotubes. The molecular structure and composition of MWNTs/Fe₃O₄ NPs/PANI nanotubes were characterized by Fourier transform infrared spectra (FTIR), energy dispersive X-ray spectrometry (EDX), X-ray photoelectron spectra (XPS), X-ray diffraction (XRD) and Raman spectra. UV-vis spectra confirmed the existence of PANI and its response to acid and alkali. As a multifunctional material, the conductivity and magnetic properties of MWNTs/Fe₃O₄ NPs/PANI composites nanotubes were also investigated.     

Microwave-assisted synthesis and electrochemical capacitance of polyaniline/multi-wall carbon nanotubes composite

Polyaniline/multi-wall carbon nanotubes composite (PANI/MWNTs) was rapidly synthesized by microwave-assisted polymerization. Transmission electron microscope (TEM) image revealed that this composite was a core–shell structure with PANI layers (50–70 nm). Electrochemical behavior of the composite was evaluated by cyclic voltammetry (CV) and galvanostatic charge–discharge tests with a two-electrode system. An enhanced specific capacitance of 322 F/g with a specific energy density of 22 W h/kg was about 12 times that of MWNTs. This composite also exhibited a good rate capability, retaining up to 87% of initial capacity at a current density of 5 mA/cm².     

Template synthesis of tin-doped indium oxide (ITO)/polymer and the corresponding carbon composite hollow colloids

SnO₂, In₂O₃, and Sn-doped In₂O₃ (ITO)/polymer and the corresponding carbon composite hollow colloids are template synthesized. It is essential that the sulfonated gel shell of the cross-linked polystyrene hollow colloid can favorably induce adsorption of target precursors. After being calcined in air to remove the template, SnO₂, In₂O₃, and ITO hollow colloids are obtained. Because the cross-linked polymer gel can be transformed into carbon in nitrogen at higher temperature such as 800 °C, metal oxide/carbon hollow colloids are consequently derived, whose shells are mesoporous. The SnO₂-, In₂O₃-, and ITO-containing polymer or carbon composite hollow colloids will be promising in sensors, catalysts, and fuel cells as electrode materials. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Preparation,characterization and application of polyaniline/epoxide polysiloxane composite films

Composites of polyaniline(PAn) and epoxide polysiloxane(EPSi) are reported for the first time. EPSi is designed, synthesized and N-grafted onto the PAn backbone through covalent bonds. As-prepared EPSi-g-PAn composites are soluble in organic solvents and the corresponding films can be easily produced via a simple solution-casting procedure. The composite films combine the mechanical characteristics of EPSi and the chemical properties of PAn, enabling the facile introduction of the noble metal particles. The successful fabrication of the composites is confirmed by the investigation of the molecular structure, crystalline structure and microstructure of the materials. The resulting composite films containing noble metal particles are employed as the catalysts for the hydrogenation of phenol to produce cyclohexanone, which exhibit the convenience and recyclability for usage as well as the high catalytic activities, including the conversion ratio of 97%-100% and the selectivity as high as 84%-98%. The present work not only provides a new method to improve the processability of the conducting polymers but also describes a kind of composite materials that may display outstanding preformances in industrial catalysis.     

Hard template synthesis of conducting polymers: a route to achieve nanostructures

The article reviews the application of a hard template approach in the formation of conducting polymers nanostructures. The method involves the synthesis of a polymer within the pores or channels of a template. The influence of synthesis conditions on fundamental features of nanostructured polypyrrole, polyaniline, and their derivatives is discussed. Dedicated to the 70th birthday of Professor Oleg Petrii.     

Effect of electrostatic forces control on the structure and properties of polyaniline/graphene oxide nanocomposite

The effects of electrostatic forces (EF), control on the morphology, structure, and electrochemical properties of polyaniline, PANI/graphene oxide (GO), nanocomposites prepared by interfacial electropolymerization (IEP), are studied in this work. FESEM images showed that the IEP method can form the PANI/GO nanocomposites when the EF-control has been found mainly on the PANI nanofibers formation and growth on the GO film surface; and the EF-enhancement can form PANI nanofibers with small nano-diameter, longer length, uniform morphology, high order and well orientation as compared with the EF-reduction-formed sample. The EF-enhancement-formed PANI/GO nanocomposite showed improved electrochemical properties than that of the EF-reduction-formed sample due to the EF-enhancement that enhances the C–N structure for PANI/GO nanocomposite.     

Hydrothermal synthesis and structure determination of the new vanadium molybdenum mixed oxide V1.1Mo0.9O5 from synchrotron X-ray powder diffraction data

A new vanadium molybdenum mixed oxide V_1.1Mo_0.9O₅ [V(V)_0.2V(IV)_0.9Mo(VI)_0.9O₅] has been synthesized, as a pure phase, via hydrothermal methods in the presence of molybdic acid and vanadyl sulfate. Its crystal structure has been solved ab initio from high-resolution powder diffraction data collected at the ESRF beamline ID31. This compound crystallizes in the monoclinic symmetry, space group C2/m, with cell dimensions , , , β=90.625(3)° and Z=2 per formula. The structure consists of double strings of VO₅ square pyramids sharing edges and corners along [100] and [010], and more weakly bound along [001]. In this latter direction, the bond (V,Mo)-O=2.377 Å, while remaining long, leads for the first time to the interpenetration of the apical oxygens of the [(V,Mo)₂O₅]_n layers, resulting in a three-dimensional (3D) structure closely related to R-Nb₂O₅. This structure will be compared to the pure layer structure of V₂O₅ where this bond reaches 2.793 Å.     

Facile fabrication and characterization of novel polyaniline/titanate composite nanotubes directed by block copolymer

In this work, we present a facile method for preparation of novel polyaniline(PANI)/titanate composite nanotubes by in situ chemical oxidative polymerization directed by poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO) triblock copolymer. The block copolymer adsorbed onto the surface of the titanate nanotubes acts as a soft template. The obtained nanocomposite has a core-shell structure in which titanate nanotubes are encapsulated by uniform PANI layers. Their structure and morphology were characterized by various experimental techniques. A possible formation mechanism of composite nanotubes is also proposed in the paper.     

A highly sensitive dopamine sensor based on a polyaniline/reduced graphene oxide/Nafion nanocomposite

A nanocomposite of polyaniline/reduced graphene oxide (PANI-rGO) was synthesized using a hydrothermal method. The product was characterized by FT-IR, Raman spectra, XRD, SEM and TEM. Then the hybrid material of PANI-rGO and Nafion (PANI-rGO-NF) was prepared and used to modify glassy carbon electrode for the trace determination of dopamine (DA) employing differential pulse voltammetry (DPV). It was found that the hybrid material showed good catalytic activity toward the oxidation of DA, and no response to ascorbic acid (AA) and uric acid (UA) was observed, suggesting a high selectivity of the sensor toward DA. The peak currents were linearly correlated with the concentration of DA in the range from 0.05 μmol/L to 60.0 μmol/L (R=0.996) and 60.0 μmol/L to 180.0 μmol/L (R=0.996) with a detection limit of 0.024 μmol/L (S/N=3). The modified electrode also exhibited excellent repeatability and stability.     

Electrospun Polyaniline/Poly(ethylene oxide) Composite Nanofibers Based Gas Sensor

Camphor‐10‐sulfonic acid (HCSA) doped polyaniline (PANI)/poly(ethylene oxide) (PEO) composite nanofibers with different compositions (12 to 52 wt.% of PANI) were synthesized by an electrospinning method and their properties including optical, electrical and sensing were systematically investigated. FT‐IR shows that an increase of IR absorbance ratios of aromatic C? C stretching vibration of benzenoid rings of PANI to C? O? C symmetric vibrational modes of PEO confirmed that the PANI content in nanofiber mats increased proportionally with increase in PANI content in electrospinning solution. The band gap of PANI was determined to be 2.5 eV using UV‐Vis spectroscopy. The electrical conductivities of the nanofibers increased with an increase in the PANI content in the nanofibers. Additionally, the sensitivity toward NH₃ increased as the PANI content increased, but branched nanofibers reduced sensing response. The humidity sensitivity changed from positive to negative as the PANI content increased. The electron transport mechanism was studied by measuring the temperature dependence electrical resistivity. The negative temperature coefficient of resistance revealed a semiconducting behavior for the PANI/PEO nanofibers. The activation energy, calculated by Arrhenius plot, increased as the PANI content decreased. The power law indicated that electrons were being transported in a three dimensional matrix, and the longer hopping distance required more hopping energy for electron transport.     

ZnO-聚苯胺同轴纳米线及其列阵的制备和表征

以阳极氧化铝膜 (AAO)作模板 ,制备聚苯胺 (PANI)纳米管和PANI纳米管列阵 ;同时利用溶胶_凝胶法制备ZnO_PANI同轴纳米线和同轴纳米线列阵 .PANI纳米管和ZnO_PANI同轴纳米线的形貌通过透射电子显微镜表征 .PANI纳米管的外径约 3 0nm ,内径约 1 0nm ;ZnO_PANI同轴纳米线直径约 60nm .实验发现 ,较之ZnO纳米线 ,同轴AAO模板中纳米线列阵的可见光发射谱带兰移 ,强度显著增强 ,这可能和PANI链上的NH基团与表面Zn2 +离子之间的相互作用有关 ,以及由于ZnO纳米微粒在PANI上富集、PANI的光生载流子部分转移给ZnO微粒所致 .实验还发现分散在NaOH溶液中的同轴纳米线 ,其可见光发射谱带比AAO模板中同轴纳米线的谱带兰移更甚     

Relationship between ammonia sensing properties of polyaniline nanostructures and their deposition and synthesis methods

The ammonia absorption properties of polyaniline nanostructures are studied in terms of sensitivity, response and recovery times and stability. These characteristics are obtained by measuring, at room temperature, the absorbance variations at 632 nm. The nanostructures are synthesized either by interfacial or rapid or dropwise polymerizations with the oxidant-to-monomer mole ratio equals to 0.5 or 1. The influence of the deposition method (in-situ or drop-coating technique) as well as the nature of the dopant (HCl, CSA or I₂) on the gas detection properties are also studied. The results show a strong dependence of the morphology on the deposition method, the in-situ technique leads to the best sensitivity and response time. For this deposition method, the nanostructures sensitivity, response time and regeneration rate depend on the synthesis method, the dopant and the mole ratio. The ageing effect after 8 months under ambient conditions and the mechanism of interaction between the polyaniline nanostructures and ammonia molecules are also presented.     

Hydrothermal syntheses and structures of two novel vanadium selenites, {[VO(OH)(H2O)](SeO3)}4·2H2O and (H3NCH2CH2NH3)[(VO)(SeO3)2]

Two novel vanadium selenites {[VO(OH)(H₂O)](SeO₃)}₄·2H₂O 1 and (H₃NCH₂CH₂NH₃)[(VO)(SeO₃)₂] 2 were synthesized by hydrothermal method and their crystal structures were determined by single-crystal X-ray diffraction. It is characterized by inductively coupled plasma (ICP), thermogravimetric (TG) and elemental analyses. Compound 1 crystallizes in the monoclinic system, space group C2/c, a=21.2250(11) Å, b=12.6309(6) Å, c=17.0249(10) Å, β=96.830(3)°, V=4531.8(4) Å³ and Z=8, R₁ [I>2σ(I)]=0.0344, wR₂ [I>2σ(I)]=0.119; Compound 2 crystallizes in the monoclinic system, space group P2₁/c, a=9.6389(4) Å, b=6.9922(3) Å, c=15.0324(5) Å, β=102.297(2)°, V=989.90(7) Å³ and Z=4, R₁ [I>2σ(I)]=0.0452, wR₂ [I>2σ(I)]=0.117. {[VO(OH)(H₂O)](SeO₃)}₄·2H₂O has a 1D structure constructed from the {[VO(OH)(H₂O)](SeO₃)}_∞ chains. (H₃NCH₂CH₂NH₃)[(VO)(SeO₃)₂] has a layered structure composed of alternating VO₅ and SeO₃ units with protonated ethylenediamine as interlayer guest.