超薄SnO_2修饰Cu_2O多孔薄膜的可见光光电化学性能

在FTO(即掺杂氟的Sn O2透明导电玻璃)基底上采用两步恒流电沉积,得到厚度约500 nm的金属Cu薄膜,然后置于Sn O2溶胶中浸渍并经175°C加热氧化,制得由超薄Sn O2修饰的Cu2O多孔薄膜。利用X射线衍射(XRD)、拉曼光谱、扫描电镜(SEM)和漫反射–紫外可见光谱(UV-Vis DRS)表征了试样的结构、形貌及光学性质。通过在0.2 mol/L Na2SO4溶液中测试样品在可见光和零偏压下的光电流,分析了薄膜的光电化学性能。结果表明,超薄的Sn O2修饰层能显著增强Cu2O多孔薄膜的光电化学性能。在Sn O2溶胶中浸渍10 s所制备的超薄Sn O2修饰Cu2O多孔薄膜,其光电流密度是Cu2O未修饰薄膜的4倍。     

Application of polarisation curves to the study of the electrochemical process for producing cuprous oxide

Polarisation curves are useful for establishing the optimum experimental conditions for producing electrolytic cuprous oxide. They provide a reasonable means of determining the influence of each variable on cuprous oxide formation at an electrode surface. In this work, a sodium chloride solution was electrolysed, and sodium hydroxide and sodium nitrate (in several concentrations) were added in successive stages to determine the behaviour of the resultant systems. Finally, the effect of the presence of cuprous oxide on the cathodic behaviour of the electrode was studied. The working electrode was of copper and the experiments were conducted at different temperatures. The polarisation curves were obtained without agitating the liquid and with aerated and deaerated solutions. The passage of nitrogen during 30 min removed oxygen from the electrolyte.     

氧化亚铜在防污涂料中的应用及法律法规进展

主要阐述了氧化亚铜在防污涂料中的应用,深入分析了氧化亚铜作为杀虫剂对生物界和环境的影响等,并对世界各国针对含铜防污涂料的法律法规进行了总结。     

Neutron scattering of hydrophobically modified poly(ethylene oxide) in aqueous solutions in the presence of latex particles

The structure of aqueous solutions of hydrophobically end-capped poly(ethylene oxide), PEOM, in the presence of solid particles (latex) was investigated by small angle neutron scattering. Mono- and di-functionalised PEOMs with the same ratio of hydrophilic to aliphatic (C₁₆H₃₃) hydrophobic groups of molecular weights 16?000 and 32?000 g mol⁻¹, respectively, were compared. We used solvent conditions in which either PEOM or latex were matched by varying the ratio of water to heavy water. Initially, a decrease in the scattering intensity at small angles was observed when PEOM was added to a suspension of latex at constant concentration. A peak was observed in the structure factor which indicated repulsion between particles. The position of the peak lied at a lower q value for mono-functionalised PEO than for di-functionalised PEO. This observation may be explained by the formation of bridges between aggregates by the di-functionalised PEOM. On varying the solvent, the characteristic peak of PEOM alone disappears at low polymer concentrations due to PEOM adsorption onto the latex particles but reappears at higher polymer concentrations.     

Quantitative characterization of protective films grown on copper in the presence of different triazole derivative inhibitors

The protective films developed on copper by anodic polarization in a borate-buffered solution containing benzotriazole (BTAH), 1-hydroxybenzotriazole (BTAOH) or 3-amino 1, 2, 4-triazole (ATA) have been characterized using coulometric experiments and an electrochemical quartz crystal microbalance (EQCM). The combination of these two techniques has allowed the CuO and Cu₂O layers and the cuprous-organic layer to be analyzed quantitatively. In the presence of BTAOH, the oxide layers were very similar to those formed in inhibitor-free solution and BTAOH appeared to be adsorbed on the oxide film. In the presence of BTAH, a thick Cu₂O film was covered by a Cu-BTA film containing 8% Cu⁺ ions. Cupric oxide appeared on Cu₂O areas uncovered by Cu-BTA. In the presence of ATA, the Cu₂O layer was very thin and the greater part of Cu⁺ ions (75%) was involved in a thick Cu-ATA film.     

Adhesive and flame resistance behavior of poly(arylene ether phosphine oxide) (PEPO) and PEPO‐modified epoxy resins

Poly(arylene ether phosphine oxide) (PEPO) with controlled molecular weights and amine end‐groups was synthesized, and used as an adhesive, a coating material for adherend or a modifier for diglycidyl ether of bisphenol A (DGEBA)‐based epoxy resins. Closely related poly(arylene ether sulfone) and commercial polyethersulfone, Udel® P‐1700, were also utilized for comparison purposes. Adhesive behavior was measured via single lap shear samples as a function of coated polymer type, test temperature (R.T. and 100°C), and aging condition in boiling distilled water or 5% salt water. Flame resistance of PEPO and PEPO‐modified epoxy resin was evaluated by TGA and a flame test. PEPO exhibited better adhesive properties than PES or Udel® P‐1700. PEPO coating on an Al adherend markedly improved adhesive property of PES and Udel® even at 100°C, and after aging study failure mode changed from adhesive to cohesive with the PEPO. Aminophenyl terminated PEPO‐modified epoxy resins also exhibited highly improved adhesive behavior and flame resistance, compared to control samples. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1198–1205, 2001     

Inhibitive effect of FA derivatives on mild steel corrosion in the presence of formic acid

The influence of selected long-chain FA hydrazides and thiosemicarbazides on the corrosion inhibition of mild steel in the presence of 20% formic acid was studied. The inhibition efficiency of these compounds varied with concentration, temperature, and immersion time. All the FA derivatives in the formic acid solution followed Temkin's adsorption isotherm. The activation energies and free energies of adsorption of all the hydrazides and thiosemicarbazides also were calculated. Potentiodynamic polarization studies indicated that all the tested compounds were of mixed type. Electrochemical impedance spectroscopy was also used to investigate the mechanism of corrosion inhibition.     

Copper (hydr)oxide modified copper electrode for electrocatalytic oxidation of hydrazine in alkaline media

Stable copper (hydr)oxide modified copper electrode was prepared by cyclic voltammetry in 0.1 M NaOH solution in the potential range of −300 to 800 mV. In the first cycle the oxidation peaks of copper were observed but in the second and next cycles, they were omitted and a clean background was obtained. This indicates that an irreversible electrochemical transformation has been achieved during the first cycle and a stable layer of hydr(oxide) formed on the surface of the copper electrode. This layer protects the electrode from corrosion. This electrode can be used for electrochemical studies in the potential range of −300 to 800 mV without any interfering effects by the oxidation peaks of copper. The modified electrode was used for electrocatalytic oxidation of hydrazine. Results showed that on the bare copper electrode the oxidation peak of 10 mM hydrazine appear at 380 mV while on the copper (hydr)oxide modified copper electrode, it appear at 260 mV. About 120 mV negative shift of the peak potential indicated the catalytic activity of (hydr)oxide layer for hydrazine. The kinetic parameters were investigated by using cyclic voltammetry and chronoamperometry.     

Anisotropy of motion in solutions of poly(ethylene oxide) in the presence of the crystalline phase

Internal mobility of poly(ethylene oxide) molecules in the liquid phase of heterogeneous samples, prepared by cooling concentrated (70–90% w/w) solutions in CDCl₃ to room temperature, was characterized by n.m.r. techniques. In the liquid phase, which in all cases contained 45% (w/w) polymer, spatial restrictions of motion as well as a broadening of the distribution of correlation times were found to be induced by the presence of the crystalline phase with a dependence on morphology, as characterized by microscopic methods.     

改性氧化石墨烯对废水中重金属的吸附

简述了石墨烯的基本结构以及氧化石墨烯在结构上的优越性。概述了氧化石墨烯的主要改性方法。针对不同的影响因素,总结了改性氧化石墨烯对废水中重金属的吸附效果。对去除水体中重金属的反应机理进行了归纳,指出了改性氧化石墨烯目前应用在污水处理中存在的问题及应用前景。     

Synthesis and characterization of poly (ethylene oxide) containing copolyimides for hydrogen purification

Reverse selective membranes comprising poly(ethylene oxide) (PEO) containing copolyimides (PEO-PI) with variations of acid dianhydrides and diamines have been synthesized for hydrogen purification. The reverse selectivity of the membranes decimate the energy required for hydrogen recompression process. Factors including PEO content, PEO molecular weight, and fractional free volume (FFV) that would affect the gas transport performance have been investigated and elucidated in terms of degree of crystallinity, phase separation in the PEO domain as well as inter-penetration between the hard and soft segments. In mixed gas tests of CO₂ and H₂ mixtures, a highly condensable CO₂ out compete H₂ for the sorption sites in hard segment and diminishes H₂ permeability. Thus the CO₂/H₂ selectivity in the mixed gas tests is much higher than that in pure gas tests. Mixed gas permeation tests at 35 °C and 2atm show that the best reverse selective membranes have a CO₂ permeability of 179.3 Barrers and a CO₂/H₂ permselectivity of 22.7. The physical properties of PEO-PIs have also been characterized by FTIR, DSC, GPC, WAXS, AFM and tensile strain tests.     

Effects of YSZ powder properties on its corrosion behaviour for solid oxide membrane (SOM) electrolysis process

The solid oxide membrane (SOM) process is an environmentally friendly and innovative technology that can produce valuable metals directly from their oxides. In the SOM process, a yttria-stabilized zirconia (YSZ) tube is normally immersed the molten salt containing dissolved metal oxides and oxygen anions that move to the SOM tube where they are reduced without any emission. However, the YSZ phase transition and yttrium dissolution by the reaction with the flux reduce the SOM stability and lifetime. Here, we investigated the effect of powder characteristics on YSZ stability in the SOM electrolysis environment. Thus, powder with good formability such as high flowability and tap/untap density showed a 2% decrease in electrical conductivity, but a 17% decrease in low formability powders. The cause of the degradation is the penetration of salt ions into the lattice and the elution of yttrium ions, which results in a phase transition.     

Filled poly(2,6-dimethyl-1,4-phenylene oxide) dense membranes by silica and silane modified silica nanoparticles: characterization and application in pervaporation

The effects of silica and silane modified silica fillers on the pervaporation properties of poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) dense membranes have been studied. Crystallinity, thermal and mechanical properties of unfilled and filled PPO membranes with silica and silane modified silica nanoparticles were investigated. The surface energy together with the solubility parameters of the membranes and the nanoparticles were determined. Pervaporation separation of methanol/methyl tert butyl ether (MTBE) mixtures over the entire range of concentration were carried out using both filled and unfilled membranes. The results are discussed in terms of the solubility and the diffusivity of each liquid component in the membranes. Flory-Huggins theory was used to predict the sorption methanol selectivity. Compared to the unfilled PPO membrane, the filled PPO membranes exhibit higher methanol selectivity and lower permeability. For methanol concentration in liquid feed mixture lower than 50 wt%, methanol selectivity of the filled PPO membranes with silane modified silica is better than that of the silica filled and unfilled PPO membranes.     

Application of ultraviolet photoelectron spectroscopy (UPS) in the surface characterisation of polycrystalline oxide catalysts. I. Methodics and analytical potential

Polycrystalline oxide surfaces have been investigated by a combination of photoemission and ion-scattering techniques (UPS, XPS, ISS) to assess the analytical potential of UPS for the surface characterisation of real polycrystalline oxide catalysts. UP spectra can be obtained from a number of binary and ternary oxides when the measurement is performed at appropriate temperatures in order to ensure sample conductivity sufficient to avoid surface charging. Where applicable, UPS provides enhanced surface sensitivity (as compared to XPS) and chemical sensitivity permitting the identification of surface structures and adsorbates. The benefit of enhanced surface sensitivity has been demonstrated by the detection of V⁴⁺ species in the outmost surface layer(s) of V₂O₅. The use of the chemical sensitivity for the identification of chemical compounds on a fingerprint basis has been shown by a study of bismuth molybdate surfaces. The chemical sensitivity with respect to adsorbates has been demonstrated by the detection of N-containing species formed in the interaction of V₂O₅ with NH₃.     

Selective catalytic reduction of nitric oxide by ethylene in the presence of oxygen over Cu ion-exchanged pillared clays

Cu²⁺ ion-exchanged pillared clays are substantially more active than Cu²⁺-ZSM-5 for selective catalytic reduction (SCR) of NO by hydrocarbons. More importantly, H₂O (or SO₂) has only mild effects on their activities. First results on Cu²⁺-exchanged TiO₂-pillared montmorillonite were reported by this laboratory (Yang and Li, Ref. [1]), that showed overall activities two to four times higher than Cu²⁺-ZSM-5.

A delaminated pillared clay was subjected to Cu²⁺ ion-exchange and studied for SCR by C₂H₄ in this work. The Cu²⁺ ion-exchanged delaminated Al₂O₃-pillared clay yielded substantially higher SCR rates than both Cu²⁺-exchanged TiO₂-pillared clay and Cu²⁺-ZSM-5 at temperatures above 400°C. The peak NO conversion was 90% at 550°C and at a space velocity of 15,000 h⁻¹ (with O₂ = 2%). The peak temperature decreased as the concentration of O₂ was increased. The macroporosity in the delaminated pillared clay was partially responsible for its higher peak temperatures (than that for laminated pillared clays). At 1000 ppm each for NO and C₂H₄, the NO conversion peaked at 2% O₂ for all temperatures. H₂O and SO₂ caused only mild deactivation, likely due to competitive adsorption (of SO₂ on Cu²⁺ sites and H₂O on acid sites). The high activity of Cu²⁺-exchanged Al₂O₃-pillared clay was due to a unique combination of the redox property of the Cu²⁺ sites and the strong Lewis acidity of the pillared clay. The suggested mechanism involved NO chemisorption (in the presence of O₂) on Cu²⁺OAl³⁺-on the pillars, and C₂H₄ activation on the Lewis acid sites to form an oxygenated species.     

Electrochemical evaluation of the a carbon-paste electrode modified with spinel manganese(IV) oxide under flow conditions for amperometric determination of lithium

The participation of cations in redox reactions of manganese oxides provides an opportunity for development of chemical sensors for non-electroactive ions. This paper describes the amperometric determination of lithium ions using carbon-paste electrode modified with spinel manganese(IV) oxide under flow conditions. Systematic investigations were made to optimize the experimental parameters for lithium sensor by flow injection analysis. The detection was based on the measurement of anodic current generated by oxidation of Mn(III) to Mn(IV) at the surface of the electrode and consequently the lithium ions extraction into the spinel structure. An operating potential of 0.50 V (vs. Ag/AgCl/3 KCl mol/L) was exploited for amperometric monitoring. The amperometric signal was linearly dependent on the lithium ions concentration over the range 4.0 × 10⁻⁵ to 1.0 × 10⁻³ mol L⁻¹. The equilibrium constant of insertion/extraction of the lithium ion in the spinel structure, apparent Gibbs energy of insertion, and surface coverage of the electrode with manganese oxide, were calculated by peak charge (Q) in different concentration under flow conditions. Considering selectivity, the peak charge of the sensor was found to be linearly dependent on the ionic radius of the alkaline and earth-alkaline cations.     

Exploring the methods of synthesis,functionalization, and characterization of graphene and graphene oxide for supercapacitor applications

Graphene and graphene oxide, are attracting more attention over the last decades in the area of supercapacitor research and researchers concentrate on extensive exploration, owing to their dominating electrical conductivity, combined with mechanical properties. This review is a panoramic approach, giving insights into various aspects related to graphene and graphene oxide such as their properties, production methods, functionalities, and their applications in supercapacitors. The study ought to be beneficial to novice as well as to the domain experts. Various properties of both materials are explored and both synthesis methods are elaborated. Extra emphasis is given to bring out the role of graphene and graphene oxide in promoting the performance of supercapacitors. Synthesis methods are tabulated based on the evaluation metrics like specific capacitance and capacitance retention. Finally, the application of graphene and graphene oxide in supercapacitors are highlighted. Before concluding, perspectives along with challenges for further development are proposed and are expected to facilitate researchers in shedding light on further studies in this explorative area.     

Mass spectral characterization of the thermal degradation of poly(propylene oxide) by electrospray and matrix-assisted laser desorption ionization

The thermal degradation of poly(propylene oxide) (PPO), M_n = 2000, can be characterized by electrospray (ESI) and matrix-assisted laser desorption ionization (MALDI). ESI and MALDI spectra of partially degraded PPO provide strong support for the thermal degradation pathway previously suggested by Griffiths et al. and Lemaire et al. Although these pathways differ in detail, it is not possible to distinguish between them from the masses of the resultant degradation species. Gel permeation chromatography data indicate that both mass spectrometric methods emphasize the presence of low-mass material, particularly in the degraded samples. This is attributed to the different sensitivities of the two techniques and some in situ fragmentation during mass spectrometric analysis.     

High-performance poly(butylene oxide)/poly (ethylene oxide) block copolymer surfactants for the preparation of water-in-oil high internal phase emulsions

High-performance surfactants have been developed for the preparation of water-in-oil high internal phase emulsions (HIPE), particularly for the preparation of polymerized HIPE foams. High-efficiency surfactants with poly(butylene oxide)/poly(ethylene oxide) (BO/EO) block copolymer backbones have been developed that can stabilize an HIPE through polymerization at concentrations as low as 0.006 wt% based on total emulsion weight. Polymerizable versions have been developed that bind into the polymeric foam backbone. BO/EO block copolymer surfactants also allow preparation of polymerized HIPE foams without salt in the aqueous phase. HIPE with the BO/EO surfactants have been prepared at room temperature and polymerized at temperatures exceeding 90°C. By minimizing the required amount of surfactant, allowing the surfactant to react during HIPE polymerizations, eliminating the need for salt, and stabilizing over a broad range of temperatures, BO/EO block copolymer surfactants have demonstrated their place as high-performance HIPE surfactants.