电化学还原处理含氮化合物研究现状与展望

根据电极材料的不同,分别就硝酸盐、氮氧化物、硝基苯的电还原技术发展进行了论述,并介绍了电化学还原技术中的几种反应器。指出电极材料是影响电化学还原效果的关键因素,开发改性多金属电极和复合薄膜电极已成为电化学还原含氮化合物研究一种趋势。未来的研究重点主要在成本低、对还原产物具有选择性的电极开发,基于三维电极材料的电化学过滤反应器设计,及电极材料的耐久使用和保养再生方面。     

电化学还原处理含氮化合物研究现状与展望

根据电极材料的不同,分别就硝酸盐、氮氧化物、硝基苯的电还原技术发展进行了论述,并介绍了电化学还原技术中的几种反应器。指出电极材料是影响电化学还原效果的关键因素,开发改性多金属电极和复合薄膜电极已成为电化学还原含氮化合物研究一种趋势。未来的研究重点主要在成本低、对还原产物具有选择性的电极开发,基于三维电极材料的电化学过滤反应器设计,及电极材料的耐久使用和保养再生方面。     

Cu2O/CuO/Cu电极光电催化还原CO2

利用表面氧化法在铜基底上制备CuO纳米带(CuO NRs),通过电化学法将Cu_2O沉积到CuO NRs上,得到复合电极Cu_2O/CuO/Cu。借助X射线衍射(XRD)、透射电子显微镜(TEM)对Cu_2O/CuO/Cu复合电极的结构进行了表征。通过线性扫描伏安法(LSV)、光电流-时间测试、电化学阻抗测试对Cu_2O/CuO/Cu复合电极光电催化CO_2性能进行了考察。借助变色酸分光光度法来测定CO_2光电还原产物。结果表明:氧化铜在铜基底上呈纳米带生长;复合电极Cu_2O/CuO/Cu对CO_2有较强的光响应性,表现出优异的光电催化性能;Cu_2O/CuO/Cu复合电极光电催化还原CO_2的主要产物是甲醇,在0.1 mol/L NaHCO_3溶液中光电催化6 h后,甲醇质量浓度为32.2mg/L。     

电合成法制备纳米材料及纳米材料电极上的电催化合成

通过电化学合成前驱体直接水解法制备纳米TiO2 粉体和纳米TiO2 膜电极。用循环伏安法、循环方波伏安法和电解合成法研究了纳米TiO2 膜电极对有机合成反应的电催化活性。发现纳米TiO2 膜电极在 0 2～ - 1 2V扫描电位区间有两对氧化还原峰 (峰电位Epc1=- 0 5 6V ,峰电位Epc2 =- 0 95V ,扫描速度 10 0mV·s-1) ,具有异相氧化还原催化行为。电解结果表明 ,纳米TiO2 膜中的Ti(Ⅳ ) /Ti(Ⅲ )氧化还原电对作为媒质 ,异相间接电还原硝基苯为对氨基苯酚 (收率91 6 % ,电流效率 95 2 % )和草酸为乙醛酸 (收率 96 5 % ,电流效率 90 % )。     

香兰素在 Cu－PTFE 复合电极上的电还原行为

以纯铜片为基材,利用复合电镀法制得具有疏水性的Cu－PTFE（聚四氟乙烯）复合电极,并用作阴极应用于香兰素电还原制备香草醇。实验中分别测定了香兰素乙醇水溶液中Cu－PTFE复合电极的循环伏安、交流阻抗和Tafel极化曲线等电化学参数。结果表明,香兰素电还原制备香草醇的转化率为87．23％,电流效率为43．62％。通过对电化学行为研究的结果进行推测,香兰素在Cu－PTFE复合电极上的电极反应可能受到电子传递控制,可用RS（CCQ（CdlRct）RC）等效电路模拟复合电极／溶液界面的电化学行为。     

铜铝双金属复合离子液体的电化学行为及电沉积铜机理

铜铝双金属复合离子液体是新型碳四烷基化技术所用的绿色催化剂,电化学处理是回收工业应用过程外排复合离子液体中金属铜的有效途径之一,为此需要深入研究其电化学行为和电沉积铜机理。循环伏安研究发现,铜铝双金属复合离子液体在Pt盘电极、W盘电极和玻碳电极上的还原过程均包括铜的欠电势沉积、Cu(Ⅰ)的还原和铜的超电势沉积,氧化过程均包括Cu→Cu(Ⅰ)、Cu(Ⅰ)→Cu(Ⅱ)。计时安培研究表明,铜的成核方式为三维瞬时成核。长周期实验结果显示Cu(Ⅰ)的浓度随着时间下降的趋势变缓,表明电沉积铜速率逐步下降。电沉积电势对沉积产物的形貌影响较大,-2.60 V下的产物形貌更平整致密。XRD结果表明在-1.20~-2.60 V电势下阴极电沉积只生成金属铜。     

铜铝双金属复合离子液体的电化学行为及电沉积铜机理

铜铝双金属复合离子液体是新型碳四烷基化技术所用的绿色催化剂,电化学处理是回收工业应用过程外排复合离子液体中金属铜的有效途径之一,为此需要深入研究其电化学行为和电沉积铜机理。循环伏安研究发现,铜铝双金属复合离子液体在Pt盘电极、W盘电极和玻碳电极上的还原过程均包括铜的欠电势沉积、Cu(Ⅰ)的还原和铜的超电势沉积,氧化过程均包括Cu→Cu(Ⅰ)、Cu(Ⅰ)→Cu(Ⅱ)。计时安培研究表明,铜的成核方式为三维瞬时成核。长周期实验结果显示Cu(Ⅰ)的浓度随着时间下降的趋势变缓,表明电沉积铜速率逐步下降。电沉积电势对沉积产物的形貌影响较大,-2.60 V下的产物形貌更平整致密。XRD结果表明在-1.20~-2.60 V电势下阴极电沉积只生成金属铜。     

聚噻吩/铜复合催化剂选择性电还原CO2为甲酸盐

在气体扩散电极(GDL)上依次电沉积聚噻吩(PTh)和多晶Cu纳米颗粒,用于电催化还原CO₂,得到甲酸盐(HCOO^-)的法拉第效率最高可达88%。当在GDL上只沉积Cu时,FE值最高仅为74%。聚噻吩有助于提高HCOO^-选择性,可归因于两方面原因：一是聚噻吩的引入在气-液-固三相界面附近构筑了疏水环境,抑制析氢反应;二是在PTh/Cu界面生成了Cu—S键,可促进中间吸附态HCOO^*脱附还原生成产物HCOO^-。这项研究为设计高选择性催化还原CO₂为HCOO^-的Cu基催化剂提供了新的思路。     

5-硝基苯并咪唑酮在铜网电极上还原制备5-氨基苯并咪唑酮

研究了以5-硝基苯并咪唑酮为原料在铜网电极上还原制备5-氨基苯并咪唑酮的反应。循环伏安结果表明5-硝基苯并咪唑酮的电化学还原是一受扩散控制的不可逆反应;探讨了电极材料、电流密度、温度和通电量对产物产率的影响,在最优条件下5-氨基苯并咪唑酮的产率可达93%;电解液连续套用10次后,5-氨基苯并咪唑酮产率仍然可以维持在93%左右,与新鲜电解液效果相当。     

载钯泡沫镍电极电还原水中溴酸盐

该文介绍了一步法负载纳米形态钯于泡沫镍电极,以此Pd-Ni复合电极为阴极进行电化学还原溴酸盐的试验。泡沫镍表面负载钯以后显著增强了电极的还原性,钯负载量存在最优值。在p H为7.0、电流强度为5 m A、电极沉积液为5 mmol/L的条件下制备的复合电极反应3 h对溴酸盐去除率可达90.7%。水中溴酸盐电还原的稳定产物是溴离子,且占绝大部分。p H为6-8的酸性条件有利于电还原。因此,电化学还原水中溴酸盐具有一定的可行性。     

硝基苯在离子液体BPyBF4/H2O中的电化学行为

在离子液体1-丁基吡啶四氟硼酸盐(BPyBF₄)的水溶液中,采用循环伏安法(CV)、计时电流法(CA)、恒电位电解及原位红外光谱法(in-situ FTIRS)等研究了硝基苯在铂电极上的电化学还原行为。研究结果表明:硝基苯在离子液体BPyBF₄/H₂O体系中的还原过程是受扩散控制的,其还原产物主要是偶氮苯,经估算得到硝基苯在该体系中的扩散系数为3.1×10^-7 cm²·s^-1,提高温度和加入一定浓度的水均有利于硝基苯在该体系中的电化学还原。     

Promotion of the electrochemical hydrogenation of nitrobenzene at hydrogen storage alloys studied using a solid electrolyte method

The electrocatalytic properties of an AB₅-type hydrogen storage alloy towards the electrochemical hydrogenation of unsaturated organic compounds have been studied by a solid electrolyte method using electrochemical hydrogenation of nitrobenzene as a model reaction. Voltammetric studies reveal that the kinetics of the nitrobenzene electro-reduction on the hydrogen storage alloy electrode is similar to that on a Ni electrode. Aniline and p-aminophenol are produced as the reaction products. Compared to the Ni electrode, the production of aniline is considerably promoted on the hydrogen storage alloy electrode. Modifying the alloy surface with a thin layer of Cu enhances the reaction selectivity and current efficiency for aniline formation. Compared to a Cu electrode, the electrochemical hydrogenation of nitrobenzene to aniline is promoted on the Cu-modified alloy electrode. The hydrogenation promotion effect is attributed to the chemical reaction between nitrobenzene and metal hydrides that are electrochemically generated in situ. Hydrogen storage alloys therefore make it possible to intensify the electrochemical hydrogenation process of unsaturated organic compounds.     

Silver-coated ion exchange membrane electrode applied to electrochemical reduction of carbon dioxide

Silver-coated ion exchange membrane electrodes (solid polymer electrolyte, SPE) were prepared by electroless deposition of silver onto ion exchange membranes. The SPE electrodes were used for carbon dioxide (CO₂) reduction with 0.2 M K₂SO₄ as the electrolyte with a platinum plate (Pt) for the counterelectrode. In an SPE electrode system prepared from a cation exchange membrane (CEM), the surface of the SPE was partly ruptured during CO₂ reduction, and the reaction was rapidly suppressed. SPE electrodes made of an anion exchange membrane (SPE/AEM) sustained reduction of CO₂ to CO for more than 2 h, whereas, the electrode potential shifted negatively during the electrolysis. The reaction is controlled by the diffusion of CO₂ through the metal layer of the SPE electrode at high current density. Ultrasonic radiation, applied to the preparation of SPE/AEM, was effective to improve the electrode properties, enhancing the electrolysis current of CO₂ reduction. Observation by a scanning electron microscope (SEM) showed that the electrode metal layer became more porous by the ultrasonic radiation treatment. The partial current density of CO₂ reduction by SPE/AEM amounted to 60 mA cm⁻², i.e. three times the upper limit of the conventional electrolysis by a plate electrode. Application of SPE device may contribute to an advancement of CO₂ fixation at ambient temperature and pressure.     

SPE膜电极及其在化学传感器中的应用

Abstract The structure and proton conducting mechanism of solid polymer electrolyte (SPE) are described. Since the conductivity of electrolyte is important in SPE electrochemical cell research and development, we investigate quantitatively the conductivity of Nation membrane and its dependence on temperature and relative humidity. Experimental results show that the conductivity of Nation membrane increases with temperature and relative humidity.We also reports on the preparation and development of SPE membrane electrode with the emphasis on the mixture pressing method and impregnation-reduction process to prepare SPE composite electrode assemblies and their application to electrochemical sensors. We also investigate and fabricate a potentiometric electrochemical sensor of hydrogen and ethylene to measure the hydrogen and ethylene partial pressure.     

Study of the hypophosphite effect on the electrochemical reduction of nitrobenzene on Ni

The effect of the hypophosphite ion on the electrochemical reduction of nitrobenzene on Ni was evaluated from a cyclic voltammetric study and from constant potential electrolysis in an aqueous-ethanol alkaline medium. The results were compared with the data obtained in an hypophosphite-free solution. It was found that in an hypophosphite containing solution an unusual selective reduction of nitrobenzene to nitrosobenzene occurs. It is the first time that nitrosobenzene is detected as the reaction product of the nitrobenzene electrochemical reduction in an aqueous-ethanol solution. It is proposed that the Ni modified surface which is formed upon hypophosphite oxidation is responsible for the non reducibility of nitrosobenzene. The effect of the electrode potential on the nitrobenzene electrolysis on a Ni modified electrode was analysed. It was concluded that the highest nitrosobenzene yield (33%) and selectivity (82%) is achieved at −1.1 V. It was also found that the formation of nitrosobenzene leads to an electrode poisoning effect in the electrolysis process.     

离子液体中硝基苯的传质特性

应用循环伏安法测定了离子液体中硝基苯的扩散系数。硝基苯在离子液体中电还原,其扩散系数受硝基苯、离子液体及水的相互作用影响,随内外条件变化呈现复杂的变化规律。随硝基苯浓度增加扩散系数减小;相同硝基苯浓度时,水的浓度增加扩散系数增大;随着温度升高硝基苯扩散系数增大。     

Electrocatalysis and detection of nitrite on a polyaniline‐Cu nanocomposite‐modified glassy carbon electrode

A polyaniline (PANI)‐Cu nanocomposite‐modified electrode was fabricated by the electrochemical polymerization of aniline and the electrodeposition of copper under constant potentials on a glassy carbon electrode (GCE), respectively. Scanning electron microscope result shows that the PANI‐Cu composite on the surface of the GCE displays the nanofibers having an average diameter of about 80 nm with lengths varying from 1.1 to 1.2 μm. The electrode exhibits enhanced electrocatalytic behavior to the reduction of nitrite compared to the PANI‐modified GCE. The effects of applied potential, pH value of the detection solution, electropolymerization charge, temperature, and nitrite concentration on the current response of the composite‐modified GCE were investigated and discussed. Under optimal conditions, the PANI‐Cu composite‐modified GCE can be used to determine nitrite concentration in a wide linear range (n = 18) of 0.049 and 70.0 μM and a limit of detection of 0.025 μM. The sensitivity of the electrode was 0.312 μA μM^?1 cm^?2. The PANI‐Cu composite‐modified GCE had the good storage stability. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

High performance binder-free quaternary composite CuO/Cu/TiO2NT/Ti anode for lithium ion battery

High performance binder-free quaternary composite CuO/Cu/TiO₂ nanotube/Ti (CuO/Cu/TiO₂NT/Ti) electrode for lithium ion battery was designed and synthesized via anodization, electrodeposition and thermal oxidation at 450 °C in the air. The as-prepared binder-free quaternary composite CuO/Cu/TiO₂NT/Ti electrode was studied in terms of XRD, XPS, SEM, EDX, galvanostatic charge/discharge, cycle stability, cyclic voltammetry (CV) and AC impedance. As expected, the binder-free quaternary composite CuO/Cu/TiO₂NT/Ti electrode displayed much higher discharge capacity, cycle stability, Li⁺ diffusion coefficient than bare TiO₂NT/Ti electrode. High Li-storage activity of CuO, high conductivity of Cu and the synergy effect among various components should be responsible for improved electrochemical performances. Additionally, binder-free combination of the various components may also contribute into the modifications due to the exclusion of negative effect of polymer binder.