Facile synthesis of tin oxide nanoparticles stabilized by dendritic polymers

Tin(IV) oxide nanoparticles were synthesized via the reaction of carbon dioxide with stannate ions immobilized by dendritic polymers. For PAMAM and PPI dendrimer hosts, resultant nanoparticle diameters were 2.5-3 nm; 3-3.5 nm nanoparticles resulted from use of a poly(ethyleneimine) hyperbranched polymer. Our conditions represent the only precedent for SnO2 nanoparticulate growth using dendritic architectures, as well as a novel application for CO2 as a reactive gas for the controlled growth of metal oxide nanoparticles.     

Large-scale synthesis of ultrathin hexagonal tin disulfide nanosheets with highly reversible lithium storage

Ultrathin hexagonal SnS(2) nanosheets are synthesized via a simple hydrothermal reaction. The nanosheets have been applied as an anode for lithium-ion battery, which shows highly reversible capacity and good cycling stability with excellent capacity retention of 96% after 50 cycles.     

Incorporation of MWCNTs into leaf-like CuO nanoplates for superior reversible Li-ion storage

CuO/MWCNT nanocomposite is prepared by a simple precipitation method. The MWCNTs are incorporated into the leaf-like CuO nanoplates and build up a network to connect the CuO nanoleaves. The as-prepared CuO/MWCNT exhibits superior reversible Li-ion storage, the capacity maintains 627 mAh g^? 1 at 60 mA g^? 1 even after 50 cycles. The improved capability is ascribed to the MWCNT network in the composite, which improves the electrical contact of CuO/CuO and CuO/current collector, facilitates the charge transfer on CuO/electrolyte interfaces, and compensates the volume change of CuO during cycling.     

Rapid synthesis of tin (IV) oxide nanoparticles by microwave induced thermohydrolysis

Tin oxide nanopowders, with an average size of 5 nm, were prepared by microwave flash synthesis. Flash synthesis was performed in aqueous solutions of tin tetrachloride and hydrochloric acid using a microwave autoclave (RAMO system) specially designed by the authors. Energy dispersive X-ray analysis (EDX), X-ray powder diffraction (XRD), Brunauer-Emmett-Teller (BET) surface area analysis, nitrogen adsorption isotherm analysis, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), Fourier transform infrared (FTIR) spectroscopy, and transmission electron microscopy (TEM), were used to characterize these nanoparticles. Compared with conventional synthesis, nanopowders can be produced in a short period (e.g. 60 s). In addition, high purity and high specific surface area are obtained. These characteristics are fundamental for gas sensing applications.     

Surfactant assisted zinc doped tin oxide nanoparticles for supercapacitor applications

Zinc doped tin oxide nanoparticles were synthesized by employing sol–gel method assisted with different surfactants namely cetyl trimethyl ammonium bromide (CTAB), hexamine and polyethylene glycol 400 (PEG-400). The synthesis of uniform distribution of spherical Zn-SnO₂ nanoparticles in presence of PEG-400 was optimized. The synthesized Zn-SnO₂ nanoparticles were characterized by employing standard characterization techniques. X-ray diffraction results confirmed the product high-quality crystalline formation. The photoluminescence peaks appeared at 360?nm revealed the recombination of electron and hole from band to band emission of SnO₂ optical properties. The vibrational properties of Zn-SnO₂ nanoparticles were confirmed by both Raman and infra red spectra. The spherical morphology and nano sized product was evident in 200?nm scale SEM images. The cyclic voltammetry result of the product Zn-SnO₂ assisted PEG-400 exhibited the specific capacitance value of 312.7?F/g at scan rate of 10?mV/s and revealed the superior electrochemical properties. Moreover, the EIS and GCD studies also revealed the good supercapacitor nature with specific capacitance of 132.1?F/g at current density of 1?A/g for the product Zn-SnO₂ (PEG-400).

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Diagrammatic representation of Zn doped SnO₂ synthesis by sol-gel method with enhanced specific capacitance of 132.1?F/g at 1?A/g for Zn-SnO₂ (PEG-400).

     

Synthesis of tin and tin oxide nanoparticles of low size dispersity for application in gas sensing

Nanocomposite core-shell particles that consist of a Sn0 core surrounded by a thin layer of tin oxides have been prepared by thermolysis of [(Sn(NMe2)2)2] in anisole that contains small, controlled amounts of water. The particles were characterized by means of electronic microscopies (TEM, HRTEM, SEM), X-ray diffraction (XRD) studies, photoelectron spectroscopy (XPS), and Mossbauer spectroscopy. The TEM micrographs show spherical nanoparticles, the size and size distribution of which depends on the initial experimental conditions of temperature, time, water concentration, and tin precursor concentration. Nanoparticles of 19 nm median size and displaying a narrow size distribution have been obtained with excellent yield in the optimized conditions. HRTEM, XPS, XRD and Mossbauer studies indicate the composite nature of the particles that consist of a well-crystallized tin beta core of approximately equals 11 nm covered with a layer of approximately equals 4 nm of amorphous tin dioxide and which also contain quadratic tin monoxide crystallites. The thermal oxidation of this nanocomposite yields well-crystallized nanoparticles of SnO2* without coalescence or size change. XRD patterns show that the powder consists of a mixture of two phases: the tetragonal cassiterite phase, which is the most abundant, and an orthorhombic phase. In agreement with the small SnO2 particle size, the relative intensity of the adsorbed dioxygen peak observed on the XPS spectrum is remarkable, when compared with that observed in the case of larger SnO2 particles. This is consistent with electrical conductivity measurements, which demonstrate that this material is highly sensitive to the presence of a reducing gas such as carbon monoxide.     

A novel chelating acid-assisted thermolysis procedure for preparation of tin oxide nanoparticles

Pure tin dioxide (SnO₂) nanoparticles were synthesized via thermolysis of tin phthalate and tin oxalate in the presence of oleic acid (OA) as solvent. Oleic acid (OA) was employed as an organic solvent, which can be applied to control particle growth and to stabilize the particles. The products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FT-IR) spectroscopy, X-ray photoelectron spectroscopy (XPS) and photoluminescence (PL) spectroscopy. The orthorhombic phase SnO₂ nanoparticles with average size about 12 nm were synthesized through thermolysis of tin phthalate in the presence of oleic acid.     

Microwave-assisted synthesis of ultra-small iron oxide nanoparticles for biomedicine

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Preparation of polymer-dispersed liquid crystal doped with indium tin oxide nanoparticles

To study polymer-dispersed liquid crystal (PDLC) films doped with indium tin oxide (ITO) nanoparticles (NPs), samples were prepared by ultraviolet-initiated polymerisation based on the thiol–acrylate system. Owing to the interaction between PDLC system and ITO NPs, the content and the size of ITO NPs are the main determinants to the microstructure which plays an essential role on the electro-optical and anti-infrared properties of the PDLC films. In the polymer matrix, a novel microstructure consisting of a dense surface, micron-sized meshes and submicron meshes is found to benefit the better performances of the low driven voltage (20.7 V), the relatively high contrast ratio (8.3) and the lowest transmittance(500–2500 nm) on average at about 3.55% with maximum of merely 7.6%. Thus, it lays a solid foundation for the further investigations on the microstructure and the performance of the PDLC films. Meanwhile, it is proved that the PDLC film, improved performance through doping ITO NPs, is promising to be a superior choice in the field of energy-saving.     

Facile synthesis of graphene-supported shuttle- and urchin-like CuO for high and fast Li-ion storage

Graphene nanosheet (GNS) supported shuttle- and urchin-like CuO nanostructures are prepared by a facile low-temperature solution route. CuO nanoshuttles or urchin-like nanostructures are dispersed uniformly on GNS, forming a three dimensional CuO-GNS layer-by-layer network after stacking. When fabricated as anode materials for lithium-ion batteries, CuO-GNS composites exhibit superior Li-ion storage properties in terms of high capacity, long cycle life, and excellent rate performance. At a large current of 700 mA/g, GNS-supported CuO nanoshuttles show a higher-than-theoretical capacity of 826 mAh/g after 100 cycles, which is even larger than the reversible capacity of 771 mAh/g achieved at 70 mA/g after 40 cycles.     

Biogenic synthesis of iron oxide nanoparticles for 2-arylbenzimidazole fabrication

A simple, efficient, and ecofriendly method has been developed for the exclusive synthesis of iron oxide nanoparticles using an aqueous extract of Passiflora tripartita var. mollissima fruit. Transmission electron microscopy (TEM) and Dynamic Light Scattering (DLS) analysis show that the average particle size of spherical iron oxide nanoparticles is 22.3 ± 3 nm. The synthesized nanocatalyst is highly active for the synthesis of biologically significant 2-arylbenzimidazoles. The reaction was carried out under mild condition with excellent yields. The catalyst is easily separated by magnet and recyclable without significant loss of activity.     

New catanionic surfactants, phase stability and synthesis of ultrafine CdS nanoparticles

A systematic study on the water-intake capacity of the microemulsion formed using a catanionic surfactant (synthesized by taking equimolar mixture of acid and amine) with varying hydrocarbon chain length of the acid has been carried out. A decrease in the water-intake capacity with increase in the chain length was observed. Shorter chain length of co-surfactant (1-butanol compared to 1-octanol) led to higher water-intake capacity of microemulsions which may also be attributed to the high hydrophilic-lipophilic balance (HLB) of 1-butanol. Three new microemulsions based on catanionic surfactants have been used to synthesize quantum dots of CdS. The size of CdS quantum dots decreased with increase in chain length of the acid component of the catanionic surfactant.     

Gas sensing properties of MWCNTs decorated with gold or tin oxide nanoparticles

Gas sensors based on oxygen plasma functionalised MWCNTs and plasma-treated nanotubes decorated either with gold nanoclusters or tin oxide nanoparticles were evaluated for the detection of NO₂, CO and ethylene. The sensor active layers were deposited by airbrushing onto micro-machined silicon transducers. Sensitivity, linearity, selectivity, response and recovery times and humidity effect were studied. XPS and TEM were employed to analyse the gas sensitive films. Among the different sensors tested, those based on tin oxide decorated MWCNTs showed the highest sensitivity to NO₂ (at ppb level) and the lowest humidity cross-sensitivity when operated at room temperature.     

Hydrothermal synthesis of precursors of neodymium oxide nanoparticles

The nanometric precursors of neodymium oxide of various morphologies were prepared via a hydrothermal reaction route. The precursors and their thermal evolution to neodymium oxide phase were characterised by means of X-ray diffraction (XRD), transmission electron microscopy (TEM, HRTEM), thermal analysis (TG, DTA, EGA-MS), FTIR and atomic force microscopy (AFM). It was found that the reaction conditions (temperature, pressure) played a key role for the product formation of desired morphology and structure. At mild conditions (140 °C) precursor with unusual fibrous morphology and Nd(OH)_2.45(Ac)_0.550.45H₂O stoichiometry was obtained. Upon heating this phase transformed, via intermediate cubic oxide, into trigonal Nd₂O₃ at 800 °C. Nd(OH)₃ hydroxide obtained at severe conditions (180 °C) transformed upon heating into cubic Nd₂O₃ phase at about 500 °C and this phase was stabilised even at 800 °C. The fibrous precursors appeared to be a convenient material for preparation of homogeneous thin coatings on planar substrates is shown.     

Mechanism for the formation of tin oxide nanoparticles and nanowires inside the mesopores of SBA-15

The formation of polycrystalline tin oxide nanoparticles (NP) and nanowires was investigated using nanocasting approach included solid-liquid strategy for insertion of SnCl₂ precursor and SBA-15 silica as a hard template. HR-TEM and XRD revealed that during the thermal treatment in air 5 nm tin oxide NP with well defined Cassiterite structure were formed inside the SBA-15 matrix mesopores at 250 °C. After air calcination at 700 °C the NP assembled inside the SBA-15 mesopores as polycrystalline nanorods with different orientation of atomic layers in jointed nanocrystals. It was found that the structure silanols of silica matrix play a vital role in creating the tin oxide NP at low temperature. The pure tin chloride heated in air at 250 °C did not react with oxygen to yield tin oxide. Tin oxide NP were also formed during the thermal treatment of the tin chloride loaded SBA-15 in helium atmosphere at 250 °C. Hence, it is well evident that silanols present in the silica matrix not only increase the wetting of tin chloride over the surface of SBA-15 favoring its penetration to the matrix pores, but also react with hydrated tin chloride according to the proposed scheme to give tin oxide inside the mesopores. It was confirmed by XRD, N₂-adsorption, TGA-DSC and FTIR spectra. This phenomenon was further corroborated by detecting the inhibition of SnO₂ NP formation at 250 °C after inserting the tin precursor to SBA-15 with reduced silanols concentration partially grafted with tin chloride.     

Optical transmittance of indium tin oxide nanoparticles prepared by laser-induced fragmentation in water

Laser-induced fragmentation of indium tin oxide nanoparticles was performed in water by laser irradiation with various laser energies. Fragmentation of the nanoparticles proceeded with increased laser energy. The fragmented nanoparticles showed high transmittance in the visible region and lower transmittance in the ultraviolet and infrared regions. The optical band gap of the fragmented nanoparticles increased with decreasing average particle size. The increase of the band gap was possibly caused by the Burstein-Moss effect due to the increasing concentration of carriers generated by the surface defects of the oxygen vacancies on smaller nanoparticles.     

Self-assembly of tin oxide nanoparticles: localized percolating network formation in polymer matrix

A novel method to prepare transparent antistatic films by trapping nanoparticles in thin surface layers is proposed, and high performance of the product is demonstrated. Coating solutions consisting of surface-active antimony-doped tin oxide (ATO) nanoparticles, an organic solvent mixture of high affinity with poly(methyl methacrylate) substrate, and an ultraviolet curable resin are used for the film formation. Antistatic property of the layer is obtained at ATO concentrations above the critical concentration for percolation. A scaling analysis of the data shows that the critical concentration (0.004 volume fraction) is extremely low as compared to the value predicted by the percolation theory for randomly packed systems as well as the values in ever developed composite films filled with ATO particles. Microscopic observation of the deposited layers indicates that percolating clusters of ATO particles are localized on the layer surfaces. The excellent electrical and optical properties of the layer are attributed to the characteristic microstructure.