Synthesis of mesoporous tin oxide and its application as a LNG sensor

The nanostructured SnO2 gas sensor with Au electrodes and Pt heater has been fabricated as one unit via screen printing process. The gas sensor was tested for CH4 sensing behavior at 350 degrees C in the concentration range of 500-10,000 ppm. Those mesoporous SnO2 sensors exhibited the similar sensoring properties in CH4 and CO detection. The fast speed of response and high sensitivity were obtained for mesoporous tin oxide sensor as compared to non-porous one.     

Fabrication and characterization of nanostructured indium tin oxide film and its application as humidity and gas sensors

This paper reports the synthesis and characterization of nanocrystalline indium tin oxide (ITO) and its application as humidity and gas sensors. The structure and crystallite size of the synthesized powder were determined by X-ray diffraction. The minimum crystallite size was found 5 nm by Debye–Scherrer equation and confirmed by transmission electron microscopy image. Optical characterizations of ITO were studied using UV–visible absorption spectroscopy and Fourier transforms infrared spectroscopy. Thermal analysis was carried out by differential scanning calorimetry. Further, the ITO thin film was fabricated using sol–gel spin coating method. The surface morphology of the fabricated film was investigated using scanning electron microscopy images. For the study of humidity sensing, the thin film of ITO was exposed with humidity in a controlled humidity chamber. The variations in resistance of the film with relative humidity were observed. The average sensitivity of the humidity sensor was found 0.70 MΩ/%RH. In addition, we have also investigated the carbon dioxide (CO₂) and liquefied petroleum gas sensing behaviour of the fabricated film. Maximum sensitivity of the film was ~17 towards CO₂. Its response and recovery times were ~5 and 7 min respectively. Sensor based on CO₂ is 97 % reproducible after 3 months of its fabrication. Better sensitivity, small response time and good reproducibility recognized that the fabricated sensor is challenging for the detection of carbon dioxide.     

An alternative gas sensor material: Synthesis and electrical characterization of SmCoO3

Single-phase perovskite SmCoO₃ was prepared by a wet-chemical synthesis technique using metal-nitrates and citric acid; after its characterization by thermal analyses and X-ray diffraction, sintering at 900 °C in air, gave single phase and well crystallized powders. The powders were mixed with an organic solvent to prepare a slurry, which was deposited on alumina substrates as thick films, using the screen-printing technique. Electrical and gas sensing properties of sintered SmCoO₃ films were investigated in air, O₂ and CO₂, the results show that sensitivity reached a maximum value at 420 °C, for both gases. Dynamic tests revealed a better behavior of SmCoO₃ in CO₂ than O₂, due to a fast response and a larger electrical resistance change to this gas. X-ray diffraction made on powders after electrical characterization in gases, showed that perovskite-type structure was preserved.     

A theoretical study of gas adsorption on tin arsenic and its application as a highly sensitive NO2 sensor

Journal of Materials Science - The sensing performance of tin arsenic (SnAs) monolayer with adsorption of different gas molecules at room temperature was systematically investigated by the...     

Synthesis of the clinopyroxenes join CaMgSi2O6-NaAlSi2O6 for jewellery

Clinopyroxenes of the join CaMgSi₂O₆(diopside)-NaAlSi₂O₆ (jadeite) were synthesized in the temperature range 800–1900C and under varying pressure, 10–55 kbar. The stability regions of various compositions of diopside-jadeite have been established experimentally using different compositions of glass materials: stoichiometric composition NaAlSi₂O₆, 0.1CaMgSi₂O₆-0.9NaAlSi₂O₆, 0.2CaMgSi₂O₆-0.8NaAlSi₂O₆, 0.3CaMgSi₂O₆-0.7NaAlSi₂O₆, and 0.4CaMgSi₂O₆-0.6NaAlSi₂O₆. Unit cell parameters of synthetic clinopyroxenes with the above compositions were determined. The physical properties, such as hardness, toughness, density, and refractive index, etc., were also measured. The results show that synthetic clinopyroxenes have the same properties as the natural one. The gem quality of diopside-jadeite clinopyroxenes was achieved by synthesised on the basis of the above experiments. Various colouring agents, such as Cr₂O₃, Co₂O₃, NiO₂, Fe₂O₃, TiO₂, MnO, CuO, and their combinations, FeO-Cr₂O₃, etc., were added to obtain the different colours of gem. In addition, small amounts of the rare-earth oxides, such as CeO₂, Nd₂O₃, Sm₂O₃, Dy₂O₃, Eu₂O₃, Er₂O₃, Pr₆O₁₁, Lu₂O₃ and CuO-Eu₂O₃, Co₂O₃-Nd₂O₃, etc., were also added to produce fluorescent clinopyroxenes for jewellery.     

TiO_2基氧化物半导体氧敏传感器的研究开发进展

综合介绍 TiO2基氧化物半导体氧敏传感器的研究发展历史和 TiO2材料的特性,比较了各 种氧敏机理、制备方法、传感器的氧敏特性,就制备方法－材料微观结构－氧敏性能关系中的几 个重要问题,进行了深入的探讨,并对今后的研究开发与产业化,结合本课题组的研究工作,提出 了几点建议。     

TiO2基氧化物半导体氧敏传感器的研究开发进展

综合介绍TiO2基氧化物半导体氧敏传感器的研究发展历史和TiO2材料的特性,比较了各种氧敏机理、制备方法、传感器的氧敏特性,就制备方法－材料微观结构－氧敏性能关系中的几个重要问题,进行了深入的探讨,并对今后的研究开发与产业化,结合本课题组的研究工作,提出了几点建议。     

Preparation of nano-sized Pb2+ imprinted polymer and its application as the chemical interface of an electrochemical sensor for toxic lead determination in different real samples

In this work, a new nano-structured ion imprinted polymer (IIP) was synthesized by copolymerization of methacrylic acid-Pb(2+) complex and ethylene glycol dimethacrylate according to the precipitation polymerization. Methacrylic acid acted as both functional monomer and complexing agent to create selective coordination sites in a cross-linked polymer. A carbon paste electrode modified with IIP-nanoparticles was used for fabrication of a Pb(2+) sensitive electrode. Differential pulse stripping voltammetry method was applied as the determination technique, after open circuit sorption of Pb(2+) on the electrode and its reduction to metallic form. The IIP modified electrode showed a considerably higher response, compared to the electrode embedded with non-imprinted polymer (NIP). This indicated that the suitable recognition sites were created in the IIP structure in the polymerization stage. Various factors, effective on the response behavior of the electrode, were investigated and optimized. The introduced sensor showed a linear range of 1.0 × 10(-9) to 8.1 × 10(-7)M and detection limit of 6.0 × 10(-10)M (S/N=3). The sensor was successfully applied for the trace lead determination in different samples.     

Synthesis and characterization of polyamide-6/graphite oxide nanocomposites

Polyamide-6/graphite oxide (PA6/GO) nanocomposites were synthesized using delamination/absorption method. The morphologies of the composites were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Both XRD and TEM showed that the GO sheets were completely exfoliated and distributed uniformly in PA6 matrix. Differential scanning calorimetry results revealed that the crystallization temperatures of the composites increased compared to that of pristine PA6, which was due to the heterogeneous nucleating effect of GO. However, the half-time of crystallization of the composites were evidently longer than that of pristine PA6, indicating an apparent decrease in the crystallization rate when GO was loaded into the polymer matrix. This was due to the constraining effect of layered GO on PA6 chains. The temperature of maximum decomposition rate was increased by 53 °C only by adding 5 wt% GO, and the maximum decomposition rate of the nanocomposites reduced greatly. The storage modulus (G′) and loss modulus (G″) curves shifted to higher modulus upon addition of 1–5 wt% of GO. With increasing GO loading, the shear viscosity of the nanocomposites gradually increased compared with pure PA6.     

Synthesis and optical characterization of LiKB4O7, Li2B6O10, and LiCsB6O10 glasses

In the current work we report on the synthesis of LiKB(4)O(7), Li(2)B(6)O(10), and LiCsB(6)O(10) borate glasses. The results for their piezo-optic, acousto-optic, acoustic, elastic, refractive, optical transmission, and optical resistance properties are also presented. It is shown that some of these glasses represent efficient acousto-optic materials that are transparent down to the vacuum ultraviolet range and highly resistant to laser radiation.     

Ca3CO2O6的柠檬酸盐溶胶-凝胶合成、表征及电学性能

具有一维Co-O链的Ca3CO2O6是一类新型高温热电材料。通过柠檬酸盐溶胶-凝胶法合成粉体，采用常压烧结方式制备陶瓷体。结果表明，在700℃煅烧干凝胶就可以生成片状的Ca3CO4O9晶体，随着煅烧温度的升高，在850℃保温2h的条件下，Ca3CO4O9基本转化为短棒状的Ca3CO2O6晶体。Ca3CO2O6为P型半导体，电阻率随着温度的升高而降低，Sccbcck系数随着温度的升高而增加，功率因子也呈现单调增加。     

Synthesis of sea urchin-like cuprous oxide with hollow glass microspheres as cores and its preliminary application as a photocatalyst

Cuprous oxide (Cu₂O) microcrystals with sea urchin-like morphologies were successfully prepared on the surface of hollow glass microspheres (HGMs) using sodium sulfite (Na₂SO₃) as the reducing agent and sodium acetate–acetic acid (NaAc–HAc) as buffer solution in copper sulfate (CuSO₄) solution. The products were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), differential thermal-thermogravimetry (DTA-TG), and visible spectrophotometer. Based on the SEM images of the as-obtained samples, it was found that the HGMs played a crucial role in the formation of sea urchin-like Cu₂O. Meanwhile, the stirring time was also important for coating process. The as-prepared sea urchin-like microcrystals are cubic phase Cu₂O. The as-prepared products can be oxidized at 240 °C. The preliminary study on the photocatalytic behavior of the sea urchin-like Cu₂O showed that the photodegradation efficiency of 40 mg/L methyl orange (MO) reached 95.15% within 30 min.     

CeO2-Cu2O composite nanofibers: Synthesis,characterization photocatalytic and electrochemical application

The present study describes fabrication and electrochemical classification of one-dimensional CeO₂-Cu₂O nanofibers for photocatalysis and supercapacitor application. The utilized CeO₂-Cu₂O composite was prepared by sol–gel electrospinning method using Polyvinylpyrrolidone (PVP), Ce(NO₃)₃?6H₂O and Cu(CH₃COO)₂ as precursors. The physicochemical properties of the synthesized samples were characterized using special characterization approaches such as X-ray diffractometer (XRD), energy dispersive X-ray analysis (EDX), electron probe microanalysis (EPMA) and scanning electron microscopy (SEM). As compared to pristine CeO₂, the UV–vis spectrum of CeO₂-Cu₂O composite exhibited the absorption peak which shifted to higher wavelength. The photocatalytic activity results indicated the substantial degradation of MB dye by ～92% over the surface of CeO₂-Cu₂O nanocomposite catalyst under visible light illumination. The CeO₂-Cu₂O composite possessed higher photocatalytic activity and electrochemical capacitance than the pristine samples as supercapacitor electrode materials. The CeO₂-Cu₂O composite exhibits a specific capacitance of 329.64 F g^?1 at 5 mV s^?1, which is higher than that of the pristine CeO₂ (192.5 F g^?1) nanofibers. These results suggest the applicability of fabricated composite nanofibers as visible light active photocatalyst and as electrode material for supercapacitors.     

花状Bi_2WO_6光催化剂的制备及性能研究

采用简单水热法制备了具有三维花状结构的斜方晶Bi2WO6光催化剂,利用XRD、SEM、BET等分析技术对催化剂的结构和形貌进行了表征。考察了反应时间、Bi2WO6加入量、染料罗丹明B初始浓度和光源对罗丹明B光催化降解效果的影响。实验结果表明,180℃下水热12h合成的Bi2WO6催化剂,在加入量为2g/L,溶液pH为6.5,并以模拟日光500W氙灯(不加滤光片)为光源,光照30min内,对浓度为10mg/L的罗丹明B去除率最高达99.6%。水热制备的花状Bi2WO6具有较高的光催化活性。