Synthesis of Titanate-Based Nanotubes for One-Dimensionally Confined Electrical Properties

Structural tailoring for dimensionally confined electrical properties is fundamentally important for nanodevices and the relevant technologies. Titanate-based nanotubes were taken as a prototype one-dimensional material to study. First, Na0.96H1.04Ti3O7 center dot 3.42H(2)O nanotubes were prepared by a simple hydrothermal condition, which converted into Na0.036H1.964Ti3O7 center dot 3.52H(2)O nanotubes by a subsequent acidic rinsing. Systematic sample characterization using combined techniques of X-ray diffraction, field emission scanning electron microscopy, high resolution transmission electron microscopy, electron paramagnetic resonance, Fourier transform infrared spectroscopy, elemental analyses, and alternative current impedance indicated that both nanotubes possessed a scrolled trititanate-type structure with the (200) crystal face predominant on the tube surface. With increasing temperature, both nanotubes underwent a continuous dehydration process, which however imposed different impacts oil the structures and electrical properties, depending on the types of the nanotubes

The effect of template phase on the structures of As-synthesized silica nanoparticles with fragile didodecyldimethylammonium bromide vesicles as templates

The effect of template phase on the structures of as-synthesized silica nanoparticles with fragile DDAB vesicles as templates is reported. It is found that the template phase plays a critical role in the growth process of silica: the unstable DDAB vesicles in liquid-crystalline phase often lead to the formation of mesostructured solid spheres, and the rather stable DDAB vesicles in gel phase lead to the formation of hollow spheres with less mesostructures.

A novel sensitive solid-state electrochemiluminescence sensor material: Ru(bpy)(2+)(3) doped SiO2@MWNTs coaxial nanocable

A simple, large scale, and one-step process for the preparation of tris(2,2'-bipyridyl)ruthenium(I) (Ru(bpy)(3)(2+)) doped SiO2@carbon nanotubes (MVNTs) coaxial nanocable used for an ultrasensitive electrochemiluminescence (ECL) is presented for the first time. More importantly, a directly coated as-formed functional material on ITO electrode surface exhibits excellent ECL behavior, good stability, and high sensitivity in the presence of tripropylamine (TPA). This novel functional material will find potential applications in biosensor, electrophoresis and electroanalysis.

One-step synthesis of Ru(2,2 '-bipyridine)(3)Cl-2-immobilized silica nanoparticles for use in electrogenerated chemiluminescence detection

One-step synthesis of Ru (bpy)(3) Cl-2-immobilized (bpy = 2,2'-bipyridine) silica nanoparticles (Ru-silica nanoparticles) for use in electrogenerated-chemiluminescence (ECL) detection is reported. Ru-silica nanoparticles are prepared by using the Stober method. Compared with free Ru(bpy)(3)Cl-2, Ru-silica nanoparticles are seen to exhibit a red-shift of the UV-vis absorbance peak and a longer fluorescence lifetime, which are attributed to the electrostatic interaction of Ru(bpy)(3)(2+) and silica. Because silica nanoparticles are used as immobilization matrices, the surfaces of Ru-silica nanoparticles are easily modified or functionalized via the assembly of other nanoparticles, such as Au. For ECL detection, Au-colloid-modified Ru-silica nanoparticles are immobilized on a 3-mercaptopropyl-trimethoxysilane-modified indium tin oxide electrode surface by Au-S interaction; the surface concentration of electroactive Ru(bpy)(3)Cl-2 is obviously higher than that in silica films.

Electrochemiluminescence-based DNA detection using guanine oxidation at electrostatic self-assembly of Ru(bpy)(3)(2+)-doped silica nanoparticles on indium tin oxide electrode

A Ru(bpy)(3)(2+)-doped silica nanoparticle-[Ru@Silica] modified indium tin oxide electrode was prepared by simple electrostatic self-assembly technique, and one-electron catalytic oxidation of guanine bases in double-strand and denatured DNA was realized using the electrochemiluminescence detection means.

Tris(2,2 '-bipyridyl) ruthenium(II) doped silica film modified indium tin oxide electrode and its electrochemiluminescent properties

An approach was reported to synthesize silica hybridized ruthenium bipyridyl complex through amidation reaction by covalent attachment of bis(bipyridyl)-4,4'-dicarboxy-2,2'-bipyridyl-ruthenium to (3-aminopropyl)-triethoxysilane. The hybrid complex then was gelatinized through acid catalytic hydrolysis method and a sol-gel modified indium, tin oxide electrode was prepared via spin coating technique. As prepared indium tin oxide electrode possesses good stability therein with excellent electrochemiluminescence behavior.

Synthesis and luminescent properties of europium (III) schiff base complexes covalently bonded to silica xerogels

A new kind of luminescent organic-inorganic hydrid material consisting of Eu(III)-schiff base complex covalently bonded to silica xerogel was synthesized via the sol-gel method using a Eu (N-propylene salicylimine ligand) complex modified with pendant triethoxysilane groups (Eu(III)(salenHSi)). The Eu(III)(salenHSi) complex is characterized by Fourier transform infrared (FT-IR) spectroscopy. Luminescent properties of the complex and the resulted hybrid silica xerogels have been investigated at room temperature.

Direct electrochemistry and electrocatalysis of horseradish peroxidase immobilized in sol-gel-derived ceramic-carbon nanotube nanocomposite film

The sol-gel-derived ceramic-carbon nanotube (SGCCN) nanocomposite film fabricated by doping multiwall carbon nanotubes (MWNTs) into a silicate get matrix was used to immobilize protein. The SGCCN film can provide a favorable microenvironment for horseradish peroxidase (HRP) to perform direct electron transfer (DET) at glassy carbon electrode. The HRP immobilized in the SGCCN film shows a pair of well-defined redox waves and retains its bioelectrocatalytic activity to the reduction of O-2 and H2O2, which is superior to that immobilized in silica sol-gel film.

Electrochemical catalysis and thermal stability characterization of laccase-carbon nanotubes-ionic liquid nanocomposite modified graphite electrode

The hydrophobic carbon nanotubes-ionic liquid (CNTs-IL) get forms a stable modified film on hydrophobic graphite electrode surface. Laccase immobilized on the CNTs-IL gel film modified electrode shows good thermal stability and enhanced electrochemical catalytic ability. The optimal bioactivity occurs with increasing temperature and this optimum is 20 degrees C higher in comparison to free laccase. The improvement of laccase thermal stability may be due to the microenvironment of hydrophobic CNTs-IL gel on graphite electrode surface. On the other hand, the sensitive detection of oxygen has been achieved due to the feasibility of oxygen reduction by both of laccase and nanocomposite of CNTs-IL gel. Furthermore, the laccase hybrid nanocomposite also shows the fast electrochemical response and high sensitivity to the inhibitors of halide ions with the approximate IC50 of 0.01, 4.2 and 87.5 mM for the fluoride, chloride and bromide ions, respectively. It implies the feasibility of laccase modified electrode as an inhibition biosensor to detect the modulators of laccase.

Alternate assemblies of polyelectrolyte functionalized carbon nanotubes and platinum nanoparticles as tunable electrocatalysts for dioxygen reduction

A novel method based on electrostatic layer-by-layer self-assembly (LBL) technique for alternate assemblies of polyelectrolyte functionalized multi-walled carbon nanotubes (MWNTs) and platinum nanoparticles (PtNPs) is proposed. The shortened MWNTs can be functionalized with positively charged poly(diallyldimethylammonium chloride) (PDDA) based on electrostatic interaction. Through electrostatic layer-by-layer assembly, the positively charged PDDA functionalized MWNTs (PDWNTs) and negatively charged citrate-stabilized PtNPs were alternately assembled on a 3-mercaptopropanesulfonic sodium (NIPS) modified gold electrode and also on other negatively charged surface, e.g. quartz slide and indium-tin-oxide (ITO) plate, directly forming the three-dimensional (3D) nanostructured materials. This is a very general and powerful technique for the assembling three-dimensional nanostructured materials containing carbon nanotubes (CNTs) and nanoparticles. Thus prepared multilayer films were characterized by ultraviolet-visiblenear-infrared spectroscopy (UV-vis-NIR), scanning electron microscopy (SEM) and cyclic voltammetry (CV). Regular growth of the mutilayer films is monitored by UV-vis-NIR.

Nanoelectrode ensembles based on semi-interpenetrating network of carbon nanotubes

A method for preparing nanoelectrode ensembles based on semi-interpenetrating network (SIN) of multi-walled carbon nanotubes (MWNTs) on gold electrode through phase-separation method is initially proposed. Individual nanoelectrode owns irregular three-dimensional MWNTs networks, which is denoted as SIN-MWNTs. On the as-prepared SIN-MWNTs nanoelectrode ensembles, the assembled MWNTs clusters in nanoscale serve as individual nanoelectrode and the electroinactive lipid networks located on the top of alkanethiol monolayer are used as a shielding layer. Cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), tapping-mode atomic force microscopy (TM-AFM) and scanning electron microscopy (SEM) were used to characterize the as-prepared SIN-MWNT nanoelectrode ensembles. Experimental results indicate that the well-defined nanoelectrode ensembles were prepared through self-assembly technology. Meantime, sigmoid curves in a wide scanning range can be obtained in CV experiments. This study may pave the way for the construction of truly nanoscopic nanoelectrode arrays by bottom-up strategy.

Individual dispersion of synthetic imogolite nanotubes via droplet evaporation

Morphology of synthetic imogolite nanotubes formed in droplet evaporation was investigated by transmission electron microscopy and electron diffraction. The nanotubes form a dense entangled network at higher concentrations, while at lower concentrations the nanotubes are liable to form oriented bundles. Under enthanol atmosphere, individual dispersion of nanotubes was observed for the first time, which reveals the length polydispersity of synthetic imogolite nanotubes.

Assembly of polyoxometalates on carbon nanotubes paste electrode and its catalytic behaviors

Carbon nanotubes paste (CNTP) electrode was prepared with multi-walled carbon nanotubes and methyl silicone oil. Polyoxometalates (POMs) were assembled on the electrode surface with different methods, and investigated by cyclic voltammetry and Raman spectroscopy. Experiments showed that POMs/CNTP electrode prepared by direct method had better performance. K6P2Mo18O62 center dot 14H(2)O (P2Mo18) assembled CNTP electrode (P2Mo18/CNTP) electrode possessed good reversibility and could catalyze the reduction of bromate and iodate in 0.1 M H2SO4 Solution. Further, the multilayer films of P2Mo18 assembled CNTP electrodes were fabricated by layer-by-layer technique, which showed higher electrocatalytic activities. All these POMs assembled CNTP electrodes prepared exhibited good stability.