超声雾化喷涂工艺及优质二氧化锡透明导电薄膜的研究

报道了采用超声雾化喷涂工艺沉积优质掺杂二氧化锡透明导电半导体薄膜的实验成果 ,选用氟作为掺杂元素 ,通过改变掺杂量和工艺参数 ,可控制薄膜的方块电阻在 1 0 Ω/□以上的范围内变化 (40 0 nm膜厚 ) ,掺氟离子二氧化锡为 n型导电半导体 ,高浓度掺杂的二氧化锡薄膜光学透过率为 87%～ 90 % (采用 550 nm单色光源测透过率 )。用 X射线衍射及扫描电子显微镜分析 ,可获得该薄膜材料的微结构、表面形貌以及薄膜组成、掺杂百分含量。该成果为大规模生产优质二氧化锡透明导电薄膜 ,提供了有效、简单的方法和装置。     

SnO2‐supported palladium catalysts: activity in deNOx at low temperature

High surface area tin dioxide (174 m²/g) has been synthetised and characterised by XRD, TEM and UV‐visible DRS. DRS gives evidence for the formation of oxygen vacancies (donor levels) under reducing conditions. CO adsorption gives rise to terminal carbonyl species linked to Sn⁴⁺ and Sn²⁺. Palladium–tin oxide catalysts have been prepared from various precursors (Pd(acac)₂ and Pd(NO₃)₂) and by different preparation methods (grafting, photodeposition); they are active in deNOx reactions at low temperature (180 °C) in the presence of stoichiometric CO–NO–O₂ mixtures. A mechanism involving palladium and oxygen vacancies is proposed. This revised version was published online in July 2006 with corrections to the Cover Date.     

Fabrication and characterization of Ag-Decorated indium–tin-oxide nanoparticle based ethanol sensors using an enhanced electrophoretic method

In this paper different Indium Tin Oxide (ITO)-based ethanol vapor sensors (fabricated as thin films and nanoparticles) are presented, and their structural and sensing properties are investigated. An Electrophoretic Deposition (EPD)-Enhanced method is proposed for the fabrication of pure, and Ag-decorated indium tin oxide sensors. The proposed sensors are then compared to conventional indium tin oxide sensors fabricated by sputtering (thin film), and drop-casting method in terms of response, and working temperature. It is shown that the electrophoretic deposition method has decreased the final particle size of the indium tin oxide nanoparticles by limiting the agglomeration of nanoparticles, and increased the sparsity of the particles forming the sensing material. Results suggest that compared to the conventional sensors, the sensors fabricated by the proposed electrophoretic deposition method (i.e., the pure-indium tin oxide (EPD-TF), and the Ag-decorated indium tin oxide (Ag-EPD) sensors), has considerably better performance for the detection of the ethanol vapors, showing reduced working temperature (110 and 130 °C, respectively), higher response, and better selectivity over CO, methane, methanol, and acetone. Moreover, the response and recovery time of the proposed sensors were found to be lower than most of the previously reported indium tin oxide-based ethanol sensors, approving the positive effect of the electrophoretic method as a simple, controllable method for sensor fabrication.     

Lead detection in environmental water sample using an organoclay film-based attenuated total reflectance sensor

A novel, portable and cost-effective optical sensor for lead detection in water has been developed, which combines a miniature sensing platform based on multiple internal reflection attenuated total reflectance (MIR-ATR) with a one-step synthesized thiolated organoclay thin film. This film is highly effective for the sequestration and pre-concentration of Pb²⁺ ions. Lead was detected with high sensitivity achieved through the combination of multiple internal reflections and large Pb²⁺ uptake capacity of the organoclay after forming bright yellow lead-thiolate (PbS_x) complexes within the film. Un-optimized detection limits of 200 ppb Pb²⁺ in deionized water samples and slightly higher in Pb²⁺-spiked natural water samples were measured. The sensor response was reasonably fast and depended on the Pb²⁺ solution flow rate. The Pb²⁺ uptake at equilibrium was greater at slower flow rates, as Pb²⁺ ions require longer times to enter the galleries of the organoclay film and bind to the thiol groups. Operation of the sensor over pH values ranging from 5.0 to 7.0 appeared optimal for maximum sensitivity and longevity of the organoclay films. Lead-loaded films could resist up to 10 recycling treatments with acid before film degradation occurred.     

Highly stable covalently-bonded organic-inorganic materials: Synthesis and electrochromic properties

Indium tin oxide (ITO) electrode was modified with anilino-methyl-triethoxysilane (AMTS), and then the polyaniline film covalently bonded to ITO electrode (PANI-ITO) was prepared by the chemical oxidation polymerization. The adhesive strength of PANI film on ITO electrode was tested by sonication. It was found that PANI-ITO exhibited a much better stability than that on bare one. Cyclic voltammetry (CV) and UV–vis spectroscopy measurements indicated that the oxidative potentials of PANI-ITO decreased and the film exhibited high electrochemical activities and lithium storage capacity. Moreover, the coloration time was 2.1 s, while the bleaching time was 1.0 s. It can be found that PANI-ITO exhibits the better electrochromic properties.     

TEM observation of tin whisker

The tin whiskers spontaneously grew from the NdSn3 intermetallic compound(IMC) after exposure to ambient conditions.One such fine tin whisker with a diameter of about 600 nm was observed by transmission electron microscope(TEM).The results showed the whisker was a perfect β-Sn single-crystal without dislocations or low angle grain boundaries.The whisker growth axis was calculated as [111].There were interference fringes in the bright-field image of the tin whisker,which reflected the existence of growth str...     

Electro-oxidation of hydrolysed poly-oxymethylene-dimethylether on PtRu supported catalysts

Poly-oxymethylene-dimethylether (CH₃-O-(CH₂-O)_n-CH₃ (n = 3), abbreviated as POMM₃), which has no toxicity and a very low vapour pressure, unlike methanol, was investigated as a possible liquid fuel for a direct oxidation-type fuel cell. The electrocatalytic activity towards the oxidation of methanol, formaldehyde and a fully hydrolysed form of POMM₃ in 0.1 mol dm⁻³ HClO₄ solution was examined from 30 °C to 90 °C by using a channel flow cell system at three different types of PtRu catalysts, dispersed on high surface area supports, i.e., carbon black, antimony-doped tin oxide (Sb-SnO₂), and the latter mixed with a certain fraction of acetylene black (AB) to improve the electronic conductivity. The PtRu/Sb-SnO₂ + AB catalyst exhibited the best electrocatalytic activity and thermal stability towards the fully hydrolysed POMM₃ and formaldehyde oxidations, for which the mass activity was about ten times higher than that for methanol.     

粉煤灰对镀锡液中金属离子的吸附研究

在镀锡液中,经常由于有杂质铁离子的存在而使镀液的效能下降。使用粉煤灰作为吸附剂,研究了粉煤灰对含有Fe2+、Sn2+溶液中的金属离子的吸附规律。实验使用邻菲罗啉吸光光度法对镀锡液中的Fe2+进行了测定,使用碘量法对Sn2+进行标定。研究结果表明,10 g/L粉煤灰,粒径为33~55μm,θ为50℃时对Sn2+的吸附量最小,对Fe2+的吸附量接近最大值。     

Electrochemistry behavior of endogenous thiols on fluorine doped tin oxide electrodes

In this work the electrochemical behavior of different thiols on fluorine doped tin oxide (FTO) electrodes is reported. To this end, the mechanism of electrochemical oxidation of glutathione (GSH), cysteine (Cys), homocysteine (HCys) and acetyl-cysteine (ACys) at different pH was investigated. FTO showed electroactivity for the oxidation of the first three thiols at pH between 2.0 and 4.0, but under these conditions no acetyl-cysteine oxidation was observed on FTO.Voltammetric studies of the electro-oxidation of GSH, Cys and HCys showed peaks at about 0.35, 0.29, and 0.28 V at optimum pH 2.4, 2.8 and 3.4, respectively. In addition, this study demonstrated that GSH, Cys and HCys oxidation occurs when the zwitterion is the electro-active species that interact by adsorption on FTO electrodes. The overall reaction involves 4e⁻/4H⁺ and 2e⁻/2H⁺, respectively, for HCys and for GSH and Cys and high heterogeneous electron transfer rate constants.Besides, the use of FTO for the determination of different thiols was evaluated. Experimental square wave voltammetry shows a linear current vs. concentrations response between 0.1 and 1.0 mM was found for HCys and GSH, indicating that these FTO electrodes are promising candidates for the efficient electrochemical determination of these endogenous thiols.     

The use of scanning electrochemical microscopy for the characterisation of patinas on copper alloys

The scanning electrochemical microscopy (SECM) was employed in the feedback mode for the visualisation of the local changes of morphology and reactivity, occurring on the surface of a quaternary copper-based alloy, due to exposure to environment. First, samples artificially aged by exposure to leaching acid rain were tested. The layer of corrosion products (“patina”) was investigated by performing SECM scans and approach curves, and the information provided by this electrochemical technique was compared with SEM–EDX–Raman characterisation. Successively, to highlight the early stages of localised corrosion processes, in situ examination of the surface exposed to an acidic environment was performed. The results show that SECM is a powerful characterisation tool of the deterioration process and is able to map the precursor sites of corrosion on the bronze surface.