SVET method for characterizing anti-corrosion performance of metal-rich coatings

The galvanic interaction between a metal-rich coating and the underlying metal substrate was characterized by a new analysis method based on the scanning vibrating electrode technique (SVET). The total anodic current at various immersion periods was evaluated by integrating the anodic current density on SVET maps. Zinc-rich paints (ZRPs) coated on a steel panel were used to demonstrate the experimental approach. The anti-corrosion performance of the ZRP was analyzed based on the integrated anodic current and the experimental E_OC-i_Int diagram. Closely correlative behaviour was found between the integrated anodic current and the open-circuit potential.     

3D Printing Engineered Multi-porous Cu Microelectrodes with In Situ Electro-Oxidation Growth of CuO Nanosheets for Long Cycle,High Capacity and Large Rate Supercapacitors

Developing excellent pseudocapacitive electrodes with long cycle,high areal capacity and large rate has been challenged.3 D printing is an additive manufacture technique that has been explored to construct microelectrodes of arbitrary geometries for high-energy–density supercapacitors.In comparison with conventional electrodes with uncontrollable geometries and architectures,3 D-printed electrodes possess unique advantage in geometrical shape,mechanical properties,surface area,especially in ion transport and charge transfer.Thus,a desirable 3 D electrode with ordered porous structures can be elaborately designed by 3 D printing technology for improving electrochemical capacitance and rate capability.In this work,a designed,monolithic and ordered multi-porous 3 D Cu conductive skeleton was manufactured through 3 D direct ink writing technique and coated with Cu O nanosheet arrays by an in situ electro-oxidation treatment.Benefiting from the highly ordered multiporous nature,the 3 D-structured skeleton can eff ectively enlarge the surface area,enhance the penetration of electrolyte and facilitate fast electron and ion transport.As a result,the 3 D-printed Cu deposited with electro-oxidation-generated CuO(3 DP Cu@Cu O) electrodes demonstrates an ultrahigh areal capacitance of 1.690 F cm~(-2)(38.79 F cm~(-3)) at a large current density of 30 m A cm-2(688.59 m A cm~(-3)),excellent lifespan of 88.20% capacitance retention after 10,000 cycles at 30 m A cm~(-2) and superior rate capability(94.31% retention,2-30 m A cm~(-2)).This design concept of 3 D printing multi-porous current collector with hierarchical active materials provides a novel way to build high-performance 3 D microelectrodes.     

pH affected migrational transport of ferrocene derivative of l-cysteine in aqueous solutions: Voltammetric studies

The mass transport of biologically-active l-cysteine derivatized with the ferrocenyl group (FcCH₂Cys) was investigated voltammetrically at a microelectrode in aqueous solutions under the conditions of varying content of supporting electrolyte and at different pH values. By varying the pH conditions one could obtain samples containing differently ionized forms of the l-cysteine derivative, from a monovalent cation via a neutral form (zwitterion) to a monovalent anion. Due to the acid-base equilibrium the obtained solutions were, in fact, mixtures composed predominantly of either anionic or cationic, or neutral species of FcCH₂Cys, respectively. Under the conditions of low ionic support the mass transport of these forms is differently affected by the migrational contribution. The results obtained experimentally were in good agreement with the theoretical predictions. In the calculations it was assumed that the FcCH₂Cys forms, coexisting in the solution, contribute independently to the steady-state transport-limited current. It was also assumed that the diffusion coefficients of the FcCH₂Cys forms were equal. This was validated by the voltammetric measurements at the supporting electrolyte excess (purely diffusional conditions). The diffusion coefficients of different forms of FcCH₂Cys are very similar and the average diffusion coefficient is (5.35 ± 0.05) × 10⁻¹⁰ m²/s.The studies clearly show that the variation in the conditions of pH or/and concentration of electrolyte can change the transport rate of l-cysteine even by several tens percent.     

Microelectrode array device: Photolithographic fabrication and electrochemical characterisation

A new type of microelectrode array device has been developed using semiconductor-processing techniques. An array of 15 × 15 square electrodes as small as 1 μm, spaced 100 μm apart, has been fabricated on a silicon chip of dimensions 1.5 × 1.5 mm². Steady state electrochemistry was performed using these devices in both aqueous and non-aqueous media.     

微电极法评估储氢合金的循环寿命

本文报告了一种方法评估储氢合金电极的循环寿命。使用储氢合金粉末微电极,适当地选择电位扫描范围和扫描速度,做循环伏安曲线,用氧化峰面积代表电极的放电量,可以测得放电量随时间的变化曲线,从而得到电极容量的衰减曲线。相对于常规寿命测试方法,本方法用时大大减少,且操作简便,结果准确。     

Construction of DNA-based logic gates on nanostructured microelectrodes

Electrochemical logical operations utilizing biological molecules (protein or DNA),which can be used in disease diagnostics and bio-computing,have attracted great research interest.However,the existing logic operations,being realized on macroscopic electrode,are not suitable for implantable logic devices.Here,we demonstrate DNA-based logic gates with electrochemical signal as output combined with gold flower microelectrodes.The designed logic gates are of fast response,enzyme-free,and micrometer scale.They perform well in either pure solution or complex matrices,such as fetal bovine serum,suggesting great potential for in vivo applications.     

Generation of platinum microstructures on non-conducting surfaces by means of the scanning electrochemical microscope (SECM)

The scanning electrochemical microscope (SECM) was used to form platinum microstructures. For this purpose, a thin layer of platinum dichloride was deposited as precursor on different substrates by evaporating it in high vacuum. For the reduction of this precursor the SECM provided methyl viologen radical cations locally as reducing agent. The mechanism of the reduction is discussed.     

Depassivation current transients measured between identical twin microelectrodes in open circuit

Current transients between identical twin titanium microelectrodes have been measured in open circuit. The electrodes showed transient breakdown of passivity in 1.5 M HCl although the potential is far below the pitting potential. Measurement of the current between the twin microelectrodes in sodium sulphate solution containing no chloride showed no detectable breakdown transients above the background noise. The current transients represent the breakdown of passivity and associated nucleation of corrosion pits. Some of the open circuit breakdown events show evidence of brief metastable pit propagation in the titanium surface.     

Cavity microelectrodes for the voltammetric investigation of electrocatalysts: the electroreduction of volatile organic halides on micro-sized silver powders

In this work the use of cavity-microelectrodes is described for the study of the electrocatalytic properties of silver powders in the electroreduction of trichloromethane, taken as model compound. The key role played by the Ag surface status has driven the research towards the use of micro- and nanosized materials, whose exploitation requires the full understanding of the complex behaviour of multiphasial interfaces, and the development of the appropriate investigation methodologies. Moreover, comparison with electrodeposited silver macroelectrodes demonstrates the advantages of using cavity-microelectrodes, especially in terms of improvement of the electrocatalytic activity, insignificance of ohmic drop and double layer capacitance in the voltammetric response, and simplicity offered by the experimental procedure for renovating the electrode material and surface.     

帕金森病脑深部刺激疗法中STN靶点定位方法综述

脑深部电刺激(DBS)疗法近十年来成为治疗帕金森病、肌张力障碍、抑郁、癫痫等神经性疾病的重要疗法,手术能否取得成功的一个关键是对脑深部核团直接进行电刺激的电极触点能否准确植入脑深部核团,而这首先取决于外科医生能否准确定位核团位置。本文对近年来的临床DBS靶点定位进行调研,将定位方法分为生理层面的微电极记录以及解剖层面的医学影像两类方法,并进行归纳介绍。