Electrochemical hydrogen discharge characteristics of Pd and Pd-Ni-Rh alloy hydride electrodes catalysed by Pd/Pt-black coatings

The electrochemical hydrogen discharge characteristics of pure Pd and Pd-Ni-Rh alloy hydride electrodes, activated by a superimposed electrodeposited film of Pd/Pt-black, were investigated as a negative electrode for nickel oxide-metal hydride battery. The Pd/Pt-black superposed catalysts brought about high discharge rate characteristics of the electrodes. The best discharge characteristics were obtained for Pd-7.5 at % Rh and/or Pd-2.5 at % Ni-7.5 at % Rh alloy hydrides, the electrode surfaces of which were activated first with about 1–2 mg cm-2 of Pd-black and then almost the same amount of Pt-black.     

Preparation and electrochemical performance of uniform RuO2/Ti and RuO2‐IrO2/Ti electrode for electrolysis of NaCl solution

The electrochemical preparation of NaClO has been widely used for the production of industrial disinfectant. To reduce the cost of electrode preparation using the brushing method, this paper introduces a method for the electrodeposition for RuO₂/Ti and RuO₂‐IrO₂/Ti preparation and NaCl solution electrolysis. The deposition of Ir improves the uniformity and stability of the RuO₂/Ti electrode. The optimum preparation conditions and additive concentrations were investigated in detail through the orthogonal experiment. By adjusting the electroplating time, temperature and voltage, the electrode with a high content of available chlorine was synthesized successfully. The physicochemical properties of the as‐prepared RuO₂/Ti and RuO₂‐IrO₂/Ti were determined by XRD, SEM‐EDS, and XPS, and the electrochemical performance and lifetime of the RuO₂/Ti and RuO₂‐IrO₂/Ti was verified via an electrochemical workstation. Uniform and stable RuO₂/TiO₂ and RuO₂‐IrO₂/TiO₂ were synthesized successfully for the electrolysis of the NaCl solution.     

Electrochemical properties of Ti/SnO2-Sb2O5 electrodes prepared by the spray pyrolysis technique

Cyclic voltammetry for the ferri-ferrocyanide redox couple has been used to study the Ti/SnO₂-Sb₂O₅ electrode prepared by spray-pyrolysis under different conditions. The obtained results shows that increasing the preparation temperature and the duration of coating deposition results in a decrease of i _p and an increase of E _p for the ferri-ferrocyanide couple. This deviation from reversibility has been attributed to the formation of a titanium oxide layer at the Ti/coating interface. Concerning oxygen evolution at the Ti/SnO₂-Sb₂O₅ anodes, a mechanism is proposed in which water is discharged at the anode forming hydroxyl radicals which are further oxidized to form dioxygen. Finally, a generalized mechanism for oxygen evolution at oxide electrodes has been proposed.     

Electrochemical investigation of O2-exposed Pd electrodes supported on YSZ

Cyclic voltammetry and steady state polarization measurements were performed for the electrochemical characterization of the O₂(g), Pd/YSZ system. The effect of oxygen partial pressure was investigated in the temperature range of 350–400 °C and it was found that under polarization phase transformations can take place. Application of negative potential values, lower than a threshold value of ?0.6 V, can result in the decomposition of PdO, while the reduced species can be re-oxidized during a linear anodic potential scan. The results suggested that during the first minutes of cathodic polarization, the PdO reduction reaction dominated versus the oxygen reduction reaction, while it becomes more significant as the oxygen concentration in the gas phase increased within the range 0–6 kPa.     

Ti/IrO2+MnO2电极在酸性溶液中的电化学活性表面积

采用涂覆热分解法制备不同成分的Ti/IrO₂+MnO₂电极,利用恒电位循环伏安法研究Ti/IrO₂-MnO₂电极在硫酸溶液中的电化学表面行为,并用直线外推法定量地评价电极的电化学活性表面积。结果表明,Ti/(0.7)IrO₂+(0.3)MnO₂的伏安电荷达到最高,为电化学活性表面积最大;随着电位扫描速率增大,伏安电流密度不断增加,而伏安电荷容量逐渐减少,直到维持恒定;所有Ti/IrO₂+MnO₂电极的“内部”电化学活性表面积远大于“外部”电化学活性表面积,约为“外部”电化学活性表面积的2倍,说明电极内部存在丰富的多孔结构,真实表面积巨大,因此Ir⁴⁺/Ir³⁺转化反应多发生于内电化学活性表面区域。     

Electrochemical degradation of Ibuprofen on Ti/Pt/PbO2 and Si/BDD electrodes

The electrochemical oxidation of Ibuprofen (Ibu) was performed using a Ti/Pt/PbO₂ electrode as the anode, prepared according to literature, and a boron doped diamond (BDD) electrode, commercially available at Adamant Technologies. Tests were performed with model solutions of Ibu, with concentrations ranging from 0.22 to 1.75 mM for the Ti/Pt/PbO₂ electrode and 1.75 mM for the BDD electrode, using 0.035 M Na₂SO₄ as the electrolyte, in a batch cell, at different current densities (10, 20 and 30 mA cm⁻²). Absorbance measurements, Chemical Oxygen Demand (COD) and Total Organic Carbon (TOC) tests were conducted for all samples. The results have shown a very good degradation of Ibu, with COD removals between 60 and 95% and TOC removals varying from 48 to 92%, in 6 h experiments, with higher values obtained with the BDD electrode. General Current Efficiency and Mineralization Current Efficiency, determined for both electrodes, show a similar behaviour for 20 mA cm⁻² but a very different one at 30 mA cm⁻². The combustion efficiency was also determined for both anodes, and found to be slightly higher with BDD at lower current density and equal to 100% for both anodes at 30 mA cm⁻².     

Electrochemical degradation of phenol on the La and Ru doped Ti/SnO2-Sb electrodes

La and Ru doped Ti/SnO₂-Sb electrodes were prepared by thermal decomposition and characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). It confirmed that the surface of the La and Ru doped Ti/SnO₂-Sb electrodes presents a certain microspherical structure formed by aggregates of nanoparticles, which increases the specific area greatly and provides more active sites. The enhanced performance of the La and Ru doped electrodes arose from the increased adsorption capacity of hydroxyl radicals. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) showed an improvement of the electrochemical capacity for the La and Ru doped Ti/SnO₂-Sb electrodes. The electrochemical oxidation performance of the prepared electrode was further studied using phenol as a model pollutant. UV scans revealed that both phenol and its intermediate products are more rapidly decomposed, especially in the early stage of oxidation on the La and Ru doped electrodes. The removals of chemical oxygen demand (COD) were 86.4% and 82.1% on the Ti/SnO₂-Sb-La and Ti/SnO₂-Sb-Ru electrodes, respectively, which were higher than that on the SnO₂-Sb/Ti electrode (60.1%). The doped electrodes are demonstrated to have superior electrochemical oxidation ability for phenol.     

柠檬酸工业废水强化镉污染土壤的电化学法修复

通过批量解吸附实验和电化学修复实验,研究利用柠檬酸工业废水作为电化学修复的增效剂从高缓冲容量的天然土壤中去除镉的可行性。批量实验结果表明,当加入柠檬酸工业废水时,85%以上的镉能在土壤pH≤5.0的条件下从土壤中溶解到溶液中;在pH5.0～8.0范围内镉的解吸附率比用去离子水增加20%～45%。电化学修复实验结果表明,与相同pH值的HNO₃相比,该废水作为电极溶液可使镉在土壤中发生明显迁移;在距离阳极0～4 cm及8～10 cm处土壤镉含量由282 mg·kg^-1降低至167～200 mg·kg^-1,而在距阳极4～8 cm处土壤镉含量升高至约400 mg·kg^-1。经过514 h的电化学修复,约84.7%的镉可以从土壤中去除,其中约94.6%从土壤中去除的镉富集在阴极溶液中。可见柠檬酸工业废水是一种非常有前景的重金属污染土壤电化学修复增效剂。     

RuO2/Ti阳极电化学氧化吸收氨废气

采用溶液吸收结合电化学氧化法处理氨废气。电化学反应器采用尺寸为φ35mm×350mm的管式玻璃反应器,内壁贴附不锈钢网作为阴极,反应器中心轴向设置有φ10mm×350mm的钌钛电极(RuO₂/Ti)棒作为阳极。电极浸没在吸收液中,含氨气体从反应器底部经气体分布器导入反应器。实验结果表明,与溶液吸收相比,溶液吸收结合电化学氧化可以更长时间保持较高的氨气去除率。由于RuO₂/Ti电极产生的有效氯的间接氧化作用,氨气在NaCl溶液比在Na₂SO₄溶液中的去除率更高。以NaCl为电解液时,酸性条件下更有利于氨气的吸收和降解,并且氨气的去除率随着电流密度的增加而增加。产物分析发现氨气在NaCl和Na₂SO₄溶液中被电化学氧化后,主要产物为氮气,也有少量氨转化为硝酸根离子。     

Electrochemical incineration of chloranilic acid using Ti/IrO2, Pb/PbO2 and Si/BDD electrodes

The electrochemical oxidation of chloranilic acid (CAA) has been studied in acidic media at Pb/PbO₂, boron-doped diamond (Si/BDD) and Ti/IrO₂ electrodes by bulk electrolysis experiments under galvanostatic control. The obtained results have clearly shown that the electrode material is an important parameter for the optimization of such processes, deciding of their mechanism and of the oxidation products. It has been observed that the oxidation of CAA generates several intermediates eventually leading to its complete mineralization. Different current efficiencies were obtained at Pb/PbO₂ and BDD, depending on the applied current density in the range from 6.3 to 50 mA cm⁻². Also the effect of the temperature on Pb/PbO₂ and BDD electrodes was studied.UV spectrometric measurements were carried out at all anodic materials, with applied current density of 25 and 50 mA cm⁻². These results showed a faster CAA elimination at the BDD electrode. Finally, a mechanism for the electrochemical oxidation of CAA has been proposed according to the results obtained with the HPLC technique.     

Electrochemical decomposition of bisphenol A using Pt/Ti and SnO2/Ti anodes

Methodology for the electrochemical decomposition of bisphenol A is described. The electrochemical behaviour of bisphenol A at a Pt electrode was investigated by means of cyclic voltammetric techniques. The electrochemical oxidation of bisphenol A led to the deactivation of the electrode as a result of the deposition of an electropolymerized film. However the electrochemical decomposition of bisphenol A could be achieved by the use of a platinum coated titanium (Pt/Ti) electrode and a tin dioxide coated (SnO₂/Ti) electrode. The electrolysis was carried out galvanostatically at a constant current of 0.3 A. The mineralization of bisphenol A was monitored by determining the amount of total organic carbon. Furthermore, the generation and nature of intermediates produced in the electrochemical reactions was investigated. Although large amounts of aliphatic acids were generated by electrolysis with the Pt/Ti anode, they were produced only to a small extent in at the SnO₂/Ti anode. In the case of the SnO₂/Ti anode, bisphenol A is rapidly oxidized to carbon dioxide and water, compared to the Pt/Ti anode.     

Electrocatalytic properties of Ti/TiO2 electrodes prepared by the Pechini method

The effects of three synthesis variables on the electrochemical properties of TiO₂ prepared by the Pechini method are described. To minimize the number of experiments, a factorial design was used. It was shown that, in the presence of nitrobenzene, the temperature and the number of layers were the most important variables. The effects of these variables on the cathodic charges measured by cyclic voltammetry were –0.75 and 2.76 mC cm^–2, respectively. Explanations of these findings are based on the effect of the conditions of preparation on the morphology and microstructure of the electrodes.     

钌系涂层钛阳极的优化研究进展

简要介绍了涂层钛电极的发展历程;论述了电极涂层的催化机理、制备工艺以及失效原因,并阐述了钌系涂层钛阳极性能优化的研究进展及研究方向。     

RuO2组元对RuO2+SnO2+TiO2/Ti钛阳极微观组织、形貌的影响

通过溶胶凝胶法经涂刷、烧结、退火等工艺制备了2组组元相对含量不同的RuO2+SnO2+TiO2/Ti三元涂层钛阳极.并通过XRD, DTA, TEM分析了溶胶凝胶条件下RuO2组元对RuO2+TiO2+SnO2/Ti的电极涂层的对阳极涂层组织、晶粒尺寸和外观形貌的影响.结果发现所获得的三元涂层颗粒尺寸十分细小, 均为纳米结构, 平均晶粒尺寸小于5 nm.添加RuO2组元细化涂层晶粒的效果不显著.研究表明所获得的三元阳极涂层主要组成物相为金红石(Ru,Sn,Ti)O2固溶体, RuO2组元含量较高时涂层出现不同成分金红石相共存的现象;涂层退火温度由450 ℃升高至600 ℃后, (Ru,Sn,Ti)O2固溶体达过饱和状态, 发生脱溶分解.RuO2组元相对含量的高低不能阻止该固溶体高温发生第二相析出.添加RuO2组元的RuO2+SnO2+TiO2涂层晶粒外观呈较理想等轴状特征.RuO2含量较低的阳极试样Ru11Sn62Ti27具有较理想的晶粒组织结构和外观形貌.     

The synthesis of rGO/RuO2, rGO/PANI,RuO2/PANI and rGO/RuO2/PANI nanocomposites and their supercapacitors

Polymer Bulletin - In this work, reduced graphene oxide (rGO) was obtained by chemical reduction of graphene oxide (GO) using sodium borohydride (NaBH4). Four different nanocomposites rGO/ruthenium...     

Electrochemical degradation of azo dye C.I. Reactive Red 195 by anodic oxidation on Ti/SnO2-Sb/PbO2 electrodes

This study investigated the electrochemical degradation of C.I. Reactive Red 195 (RR195) in aqueous solution on a Ti/SnO₂-Sb/PbO₂ electrode. The influence of operating variables on the mineralization efficiency was studied as a function of the current density, the initial pH, the initial concentration of the dye and the addition of NaCl. The efficiency of RR195 mineralization decreased with increased initial concentration, from 100 mg L⁻¹ to 400 mg L⁻¹. The current density had both a positive and a negative effect on degradation rates, and no significant effect of initial pH on RR195 mineralization was observed. Measurement of absorbance was used to discriminate the effect of NaCl in the electro-oxidation process. We found that the decolouring efficiency increased whereas the mineralization efficiency decreased with the increasing concentration of NaCl. The intermediates formed during the degradation were detected by gas chromatography-mass spectrometry, and the major aromatic intermediates identified were 1-(3,6,8-trihydroxy-1-naphthyl)urea, nitrobenzene, benzo-1,4-quinone, (3,6,8-trihydroxy-1-naphthyl)carbamic acid and phthalic acid. Quantitative measurement of organic and inorganic ions was done by ion chromatography. On the basis of the reaction products identified, a possible degradation pathway for the anodic oxidation of RR195 in aqueous solution is proposed.     

微流控反应器中苯酚在Ti/SnO2-Sb2O5电极上的阳极氧化分析

目前在电化学氧化处理法降解苯酚废水的研究过程中,研究者多将重心放在活性电极的探索及制备上,而对于反应器的开发鲜有报道。就这一问题,本文研究了新型微流控反应器中苯酚的电化学降解效果。电化学氧化实验在装有Ti/SnO₂-Sb₂O₅阳极的微型流通池中操作进行,实验对循环体系的体积流率Φ_V、电极间距h的影响进行了考察。结果表明,当流通电解槽中的阴阳极间距采用微米级尺寸时,苯酚的阳极氧化反应取得了较快的氧化速度。在 em= 20 mA/cm²、Φ_V= 0.54 mL/min的电解条件下,电解2~3h苯酚去除率即可达到90%以上,相同流速下电极间距h越小降解速率越快。且由数据回归得到了苯酚的一系列随h的减小而增大的准一级反应的反应速率常数。这一结论表明微流控电解槽内的苯酚降解过程主要传质控制过程。     

Electrochemical and photoelectrochemical behaviour of passivated Ti and Nb electrodes in nitric acid solutions

Ti and Nb electrodes were passivated galvanostatically in nitric acid solutions. The electrochemical and photoelectrochemical behaviour of these electrodes was studied and compared with the behaviour of similar electrodes passivated in sulphuric acid solutions under the same conditions. The flatband potential and donor concentration of the passive films were obtained from the corresponding Mott-Schottky plots. The photoelectrochemical investigations were carried out using a pulsed laser which rendered measurements with photon energies smaller than the band gap. The results showed that the behaviour of passivated titanium in nitric acid was differing from its behaviour in sulphuric acid. The behaviour of the passivated niobium was not much affected by the exchange of the two acids.     

Catalytic performance of a Ti added Pd/SiO2 catalyst for acetylene hydrogenation

A series of Pd/SiO₂ and Pd–Ti/SiO₂ catalysts were prepared by the incipient wetness impregnation method. The catalytic performance for selective hydrogenation of acetylene to ethylene was measured under “high concentration acetylene”, “high space velocity” and “no dilution gas” conditions. The crystal structure and particle size of the catalysts were characterized by the X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), nitrogen physisorption using the BET method and transmission electron microscope (TEM). The results showed that the titanium oxide in Pd–Ti/SiO₂ catalyst was amorphous and the addition of Ti reduced the particle size of Pd significantly. Comparing to the Pd/SiO₂ catalyst, the ethylene yield increased from 64.1% to 88.3% under Pd–Ti/SiO₂ catalytic system.