Nile blue adsorbed onto silica gel modified with niobium oxide for electrocatalytic oxidation of NADH

A study of modified carbon paste electrode employing Nile blue (NB) adsorbed on silica gel modified with niobium oxide (SN) for electrocatalytic oxidation of reduced nicotinamide adenine dinucleotide (NADH) is described. The adsorbed organic dye on SN was used to prepare a modified carbon paste electrode to investigate its electrochemical properties. The formal potential (E°′) of the adsorbed NB (−230 mV vs. saturated calomel electrode, SCE) showed a shift of 70 mV towards a more positive potential value, compared to NB dissolved in aqueous solution. In solutions with pH between 6.0 and 8.0 did stability and E°′ remained almost constant. However, for a solution pH lower than 6.0 the E°′ was affected by the acidity of the contacting solution, shifting the E°′ towards more positive values. For the solution pHs between 6.0 and 8.0 the electrocatalytic activity remained almost constant. A linear response range for NADH between 1.0×10⁻⁵ and 5.2×10⁻⁴ mol l⁻¹, at pH 7.0, was observed for the electrode, with an applied potential of −200 mV versus SCE. The formation of an intermediate charge transfer (CT) complex was proposed to the CT reaction between NADH and adsorbed NB. The heterogeneous electron transfer rate, k_obs, was 1400 M⁻¹ s⁻¹ and the apparent Michaelis-Menten constant, was 0.21 mM at pH 7.0 evaluated from rotating disk electrode (RDE) experiments with an electrode coverage of about 5.2×10⁻⁹ mol cm⁻². The increase in the reaction rate between NADH and the immobilized NB compared to those obtained with dissolved NB was assigned to the shift of the E°′ towards more positive values.     

Activity of gold towards methylamine electrooxidation

The kinetics of methylamine oxidation at a gold electrode in contact with an alkaline electrolyte solution was studied. The adsorptive behaviour of substrate molecules was determined by changes in the differential capacitance of the double layer at the electrode/solution interface. The electrooxidation of methylamine occurs only in the potential range of gold oxide layer formation. The general reaction pathways of methylamine oxidation on the gold electrode is proposed.     

Electropolymerization of chlorinated phenols on a Pt electrode in alkaline solution. Part II: An electrochemical quartz crystal microbalance study

Electropolymerization of phenol and mono-, di-, tri-, pentachlorophenols was studied using EQCM on a Pt electrode at 0.78 V (SHE) in 1 M NaOH solution containing 0.1 M of the corresponding phenol. The highest electropolymerization rate was found for ortho-substituted chlorophenols indicating a weak fouling of the electrode. Low electropolymerization rates for para-substituted chlorophenols suggest a low permeability of the polymer film, resulting in rapid electrode fouling. The EQCM data suggest that electropolymerization of chlorophenols occurs without Cl-elimination for the monomers with unsubstituted ortho and para positions. Dechlorination is most pronounced for electropolymerization of para-substituted isomers. The mechanism of electropolymerization of chlorophenols is discussed.     

Electrodeposition of catalytically active nickel for the oxygen evolution reaction — effects of anionic composition

Nickel electrodes were prepared by electrodeposition in electrolytes of various anionic compositions. The deposition conditions and bath types were evaluated with special emphasis on the electrocatalytic properties for the oxygen evolution reaction (OER). Electrochemical characterizations in a 5 mol/L KOH solution at 25°C showed that the electrode deposited from the chloride bath, having a low Tafel slope of 50 mV/dec and an overpotential of 396 mV at 100 mA/cm², is the most catalytically active among electrodes prepared in electrolytes of various anionic compositions. The electrode activity for the OER is related to the real surface areas, which depend on the anion compositions in the deposition bath and the deposition conditions.     

Ni添加对Ti_(0.47)V_(0.28)Mn_(0.15)Cr_(0.1)储氢合金电化学性能的影响

通过X射线衍射谱(XRD)、气态吸放氢行为(PCT曲线)、电化学充放电性能、电化学阻抗谱(EIS),考察了Ni添加对Ti_(0.47)V_(0.28)Mn_(0.15)Cr_(0.1)储氢合金的电化学性能的影响。结果表明:Ti_(0.47)V_(0.28)Mn_(0.15)Cr_(0.1)的电化学活性很差,在碱液中几乎不能放电,添加Ni之后得到了明显改善。随着Ni含量的增加,Ti_(0.47)V_(0.28)Mn_(0.15)Cr_(0.1)Ni_x(x=0～0.25)合金电极的放电容量先增大后减小,在x=0.15时达到最大值310mA·h·g~(-1)。     

Studies on film potentiometric stripping analysis: effects of electrochemical parameters

Film potentiometric stripping analysis (PSA) is a novel method for concentrating the test ion directly on a glassy carbon electrode with subsequent stripping by a chemical oxidant, the redissolution step being followed by a chronopotentiometric sequence. The electrochemical parameters governing both preconcentration and redissolution steps are studied on a rotating disk electrode: experimental results are compared with the theoretical developments recently published. Except for the influence of rde rotation rates on each step and on analytical parameters, experiments and theory are in agreement. Discrepancies concerning the rotation rate effects are studied by potentiostatic coulometry and voltammetry measurements in regard to the preconcentration step: the rotation rate effects are based on the physical behaviour of the rde. Routine analysis is carried out using film PSA, Pb(II) as the test ion and Fe(III) as oxidizing agent, in perchlorate medium.     

大容量矿热炉用电极糊的研制

大容量矿热炉用电极糊，采用电煅无烟煤为主要原料，加入一部分石墨碎，选用合适的配方，其理化指标高，使用效果好．     

流化床电化学反应器研究进展

流化床电化学反应器是一种三维颗粒电极反应器,以其比表面积大、传质速率高而备受关注。就流化床电化学反应器在导电机理、数学模型、结构放大以及应用领域的研究现状和进展进行了综述,阐明了该类反应器开发、设计和模型化方面存在的问题,并提出了研究方向。     

三价铬电镀用氧化物涂层钛电极的电化学行为

采用极化曲线、循环伏安曲线及钝化曲线研究了三价铬电镀用含IrO2涂层钛电极的电化学行为.电极表面的扫描电镜照片表明,部分IrO2分散在针状结晶中,其余则分散在非晶相中.分析了三价铬镀铬过程中产生六价铬的原因.所研制的I型氧化物涂层钛电极具有高的析氧活性,其电催化活性与国外某公司的钛电极相当.在三价铬镀铬过程中,采用该电极连续电解120 A·h后,镀液中无Cr(Ⅵ)产生.     

石墨防爆片静态变形及应力分析

本文旨在通过对石墨防爆片的变形、应力分布及爆破压力的试验研究,探讨以石墨电极为原材料加工石墨防爆片的可行性。文中运用有限单元法及薄板理论对该防爆破片的应力分布做了初步分析,并以电测和爆破试验验证了以薄板理论为基础的爆破压力计算公式,可供进一步研究时参考。