纳米电极上单个银纳米颗粒氧化电流分辨能力的研究

在单体电化学的研究中,提高信号分辨能力是一项挑战.缩小电极尺寸有利于对体系噪音电流的控制,有望提高电流的分辨能力.本研究制备了直径为480 nm的铂纳米圆盘电极,选用银纳米颗粒碰撞电极产生银电化学氧化行为作为模型,考察了纳米电极相对于微米电极在单体电化学信号分辨能力上的优化作用.研究表明,不同尺寸电极上观察到的银纳米颗粒的碰撞频率符合扩散控制的碰撞规律.说明单个电流信号对应于单个纳米颗粒的电化学氧化过程.同时,当电极尺寸缩小至纳米尺度后,噪音电流下降50%左右,提高了对银纳米颗粒碰撞电极过程中氧化电流的分辨能力.研究结果表明使用纳米电极能进一步提高对单体电化学中微小电流的检测能力.     

亚甲紫的电化学聚合和亚硝酸根的电催化还原

运用循环伏安法在光谱纯石墨电极上制备了亚甲紫聚合修饰电极，在酸性，中性和碱性溶液中，亚甲紫单体均能在电极上进行电化学了和合得到性能稳定的亚甲紫聚合膜。研究了实验条件对膜生长过程的影响和亚甲紫聚合膜修饰电极的电化学行为，并讨论了该修饰电极对亚硝酸根的电催化还原作用。     

单纳米颗粒在超微电极上的碰撞电化学分析：微电极和纳米管电极

纳米颗粒的功能与其尺寸、电荷密度和表面化学性质等密切相关,因此研究其内在关系至关重要。近年来,基于纳米颗粒碰撞的电化学方法可以实现对单个纳米颗粒的尺寸、浓度和聚集状态快速检测,进而有效区分纳米颗粒的个体差异和探索单个颗粒活性-结构之间的关系。鉴于电极的尺寸、形状对单颗粒碰撞结果存在显著影响,本文将重点介绍不同颗粒（金属、半导体和绝缘体）与传统超微电极和纳米管电极之间的碰撞行为,并基于目前纳米电化学碰撞技术的不足,展望未来纳米电化学碰撞技术的发展方向。     

酸性溶液中硝基苯在WC电极上的电化学还原

以聚四氟乙烯为粘接剂制成碳化钨(WC)电极.采用循环伏安法、线性扫描法和恒电位阶跃法研究了硝基苯在酸性溶液中WC电极上的电化学行为.实验表明:WC电极对硝基苯的还原具有较好的活性,电极过程受扩散和电化学步骤混合控制;表观活化能为23.7kJ·mol 1,其中,电化学步骤的活化能10.91kJ·mol 1.     

氧化还原蛋白质在模拟生物膜修饰电极上的直接电化学

评述了氧化还原蛋白在模拟生物膜这种新型的化学修饰电极上的直接电化学研究的进展。对蛋白质在表面活性剂薄膜电极和多层复合薄膜电极上的电化学行为、模拟生物膜的超分子结构以及蛋白质在该类薄膜修饰电极上对不同底物的电催化性质进行了较详细的介绍。     

动态阻（容）抗法研究Cl^—对银铟硒上电化学振荡的影响

采用现场动态阻（容）抗法测试技术，研究在不同支持电解质溶液中，过氧化氢在电沉积银铟硒电极上阴极还原过程的电化学振荡行为，振荡前后，电极的表面组成亦由ＡＥＳ能谱测得，根据实验结果，详细讨论了氯离子对此电化学振荡机理的影响。     

碳纳米纤维糊电极电化学发光法测定甲硫哒嗪

制备了基于碳纳米纤维糊电极(CFPE)的新型电化学发光传感器.运用电化学方法对CFPE进行了表征,并考察了三联毗啶钉和甲硫哒嗪在此电极上的电化学行为和电化学发光行为.结果表明,该电极表现出很好的电化学活性和电化学发光响应.基于甲硫哒嗪对三联吡啶钉电化学发光的增强作用,建立了测定甲硫哒嗪的电化学发光新方法.实验考察了缓冲...     

吲哚-3-乙酸分子印迹聚合物膜电化学传感器的研制

利用分子印迹技术,以吲哚-3-乙酸(IAA)为模板分子,甲基丙烯酸为单体,在玻碳电极表面采用原位聚合制备分子印迹敏感膜.采用方波伏安法对吲哚乙酸在该印迹电极上的电化学行为进行了研究.结果表明,0.62 V(vs.SCE)处的峰电流与吲哚乙酸的浓度在5.0×10-6～2.0×10-4mol/L范围内呈线性关系,检出限(S...     

盐酸青藤碱在铅笔芯电极上的电化学性质及应用

研究了盐酸青藤碱在1B、2B、4B铅笔芯电极上的电化学行为,发现盐酸青藤碱在2B铅笔芯电极上具有良好的电化学行为。通过考察pH、底液、温度、静置时间等对盐酸青藤碱在2B铅笔芯电极上的电化学行为的影响,建立了以2B铅笔芯电极为工作电极测定盐酸青藤碱的电化学分析新方法。该方法氧化峰电流与盐酸青藤碱在0.146~36.585mg/L范围内呈良好的线性关系,相关系数r=0.9948,检出限为0.049mg/L,可应用于测定盐酸青藤碱肠溶片中盐酸青藤碱含量。进一步探讨了盐酸青藤碱在2B铅笔芯电极上的电化学反应机理。     

结合光学成像技术研究单颗粒碰撞电化学

近年来,单颗粒碰撞技术在纳米电化学领域受到广泛关注. 该技术通常控制超微电极处于某一电位,检测单个纳米颗粒随机碰撞到电极表面后产生的瞬时电流. 通过分析电流信号,可以研究单个纳米颗粒的性质. 尽管该技术可以检测单个纳米颗粒的电化学或电催化电流,但是传统的单颗粒碰撞技术缺乏空间分辨率,难以识别和表征特定的纳米颗粒. 因此,结合光学成像技术研究单颗粒碰撞电化学来补充电化学技术缺失的空间信息已成为一种趋势. 本文首先简要综述了单颗粒碰撞技术的三种检测原理,主要介绍了近年来单颗粒碰撞技术与荧光显微镜、表面等离激元共振显微镜、全息显微镜和电致化学发光相结合的研究进展,最后展望了单颗粒碰撞技术未来的发展趋势.     

Optical-facilitated single-entity electrochemistry

Single-entity electrochemistry focusing on the study of transient electrochemical process at the confined interface, has become a promising field that addresses questions from multi-disciplines such as cellular biology, material chemistry, organic chemistry, etc. It offers the fruitful information hidden in bulk electrochemical measurements. As the optical techniques improve in spatial and temporal resolution, the combination of electrochemistry with optical microspectroscopy provides more comprehensive information of single-entity electrochemistry. Herein, we review recent progress made in optical–electrochemical measurements covering three aspects from the precise localization and temperature measurements of single compartments, to the in-situ tracking of dynamic behaviors of single nanoparticles in electrochemical process, and to the monitoring confinement-controlled electrochemistry at the single molecule/ion level. The review demonstrates how these optical methods are innovatively integrated with single-entity sensing. It also reveals how these optical–electrochemical combinations push single-entity electrochemistry forward.     

Nanoimpacts at Active and Partially Active Electrodes: Insights and Limitations

While the electrochemical nanoimpact technique has recently emerged as a method of studying single entities, it is limited by requirement of a catalytically active particle impacting an inert electrode. We show that an active particle-active electrode can provide mechanistic insight into electrochemical reactions. When an individual Pt electrocatalyst adsorbs to the surface of a partially active electrode, further reduction of electrode-produced species can proceed on the nanocatalyst. Current transients obtained during hydrogen evolution allow simultaneous measurement of the Pt catalyst over different length scales, size dependency suggests H atom intercalation as a catalytic deactivation mechanism. Although results show that outer-sphere redox probes are unproductive for particle characterization, the breadth of inner-sphere electrochemical reactions makes this a promising method for understanding the properties of catalytic nanomaterials, one at a time.     

A 30 nm Nanopore Electrode: Facile Fabrication and Direct Insights into the Intrinsic Feature of Single Nanoparticle Collisions

Clarifying the hidden but intrinsic feature of single nanoparticles by nanoelectrochemistry could help understand its potential for diverse applications. The uncontrolled interface and bandwidth limitation in the electrochemical measurement put the obstacle in single particle collision. Here, we demonstrate a well‐defined 30 nm nanopore electrode with a rapid chemical‐electrochemical fabrication method which provides a high reproducibility in both size and performance. A capacitance‐based detection mechanism is demonstrated to achieve a high current resolution of 0.6 pA ±0.1 pA (RMS) and a high the temporal resolution of 0.01 ms. By utilizing this electrode, the dynamic interactions of every single particle in the mixture could be directly read during the collision process. The collision frequency is two orders of magnitude higher than previous reports, which helps reveal the hidden features of nanoparticles during the complex and multidimensional interaction processes.     

Single Fusion Events at Polarized Liquid–Liquid Interfaces

A new electrochemical framework for tracking individual soft particles in solution and monitoring their fusion with polarized liquid–liquid interfaces is reported. The physicochemical principle lies in the interfacial transfer of an ionic probe confined in the particles dispersed in solution and that is released upon their collision and fusion with the fluid interface. As a proof-of-concept, spike-like transients of a stochastic nature are reported in the current–time response of 1,2-dichloroethane(DCE)|water(W) submilli-interfaces after injection of DCE-in-W emulsions. The sign and potential dependence of the spikes reflect the charge and lipophilicity of the ionic load of the droplets. A comparison with dynamic light scattering measurements indicates that each spike is associated with the collision of a single sub-picoliter droplet. This opens a new framework for the study of single fusion events at the micro- and nanoscale and of ion transport across biomimetic soft interfaces.     

铂电极BZ反应体系的系统动力学分析

在一定的条件下,将铂电极BZ化学反应的六变量高维动力学系约化为三变量体系,同时对该体系进行了全面的系统动力学分析.研究结果表明,通过改变耦合体系的外控参数条件,在将体相保持在均一稳定定态的参数范围内,电极反应相可能进入振荡区,而呈现出电极反应相与体相的动力学行为不一致性.进一步计算出体相处于非振荡状态时,电极反应相产生电化学振荡的外控参数区域.     

Various Current Responses of Single Silver Nanoparticle Collisions on a Gold Ultramicroelectrode Depending on the Collision Conditions

Collisions of silver nanoparticles (NPs) with a more electrocatalytic gold or platinum ultramicroelectrode (UME) surface have been observed by using an electrochemical method. Depending on the applied potential to the UME, the current response to the collision of Ag NPs on the UME resulted in various shape changes. A staircase decrease, a blip decrease, and a blip increase of the hydrazine oxidation current were obtained at an applied potential of 0.33, 0.80, and 1.3 V, respectively. Different collision behaviors of Ag NPs on the UME surface were suggested for each shape of current response. Ag NP attachment, which hindered the diffusion flux to the UME, caused a staircase decrease of the electrocatalytic current. Instantaneous blocking of the hydrazine oxidation by Ag NP collision and, following recovery of the current by means of oxidation of Ag NP, caused a blip decrease of the electrocatalytic current. The formation of a higher oxidation state of Ag on the Ag NP and its electrocatalytic hydrazine oxidation resulted in a blip increase of the electrocatalytic current. The analysis of the current response of a single NP collision experiment can be a useful tool to understand the various behaviors of NPs on the electrode surface.     

Scanning electrochemical cell microscopy: A natural technique for single entity electrochemistry

Scanning electrochemical cell microscopy (SECCM) is a robust and versatile scanning electrochemical probe microscopy technique that allows direct correlation of structure–activity at the nanoscale. SECCM uses a mobile droplet cell to investigate and visualize electrochemical activity at interfaces with high spatiotemporal resolution, while also providing topographical information. This article highlights diverse contemporary challenges in the field of single entity electrochemistry tackled by the increasing uptake of SECCM globally. Various applications of SECCM in single entity electrochemistry are featured herein, including electrocatalysis, electrodeposition, corrosion science and materials science, with electrode materials spanning particles, polymers, two-dimensional materials and complex polycrystalline substrates. The use of SECCM for patterning structures is also highlighted.     

Electrochemical characteristics of poly(ophenylendiamine) film electrodes in phosphatic solution

The electrochemical characteristics of poly(o-phenylendiamine) (POPD) film modified electrodes have been investigated using different electrochemical techniques.The main interest is focused on the effect of potential and film thickness on the electrode process.Good agreement has been found for the apparent diffusion coefficient estimated by chronocoulometry and impedance spec-troscopy.The charge transfer process within POPD films is diffusion processes at negative and positive overpotentials and electron hopping mechanism at formal potential.The POPD film conductivity of the oxidized state is better than that of the reduced state.For all electrode processes,the H+ may penetrate the film/electrolyte interface and take part in charge transfer or protonation-deprotonation of phenazine rings.     

Stochastic collision electrochemistry of single silver nanoparticles

The electrochemical oxidation of single colloidal Ag nanoparticles (NPs) at an electrode surface has previously been studied as an in situ particle-sizing methodology. However, the discovery of multipeak amperometric behavior in 2017 sparked new interest toward understanding the precise physical mechanism of the manner in which a freely diffusing Ag NP interacts with the electrode surface. Random walk simulations, unique electrochemical experiments, and correlated optical/spectroscopic techniques have revealed exciting new results regarding the physical and chemical processes occurring on single NP collision.     

锂电池电极过程的原位电化学原子力显微镜研究进展

随着人类对能源的使用与存储需求不断增加,高能量密度和高安全性能的二次锂电池体系正在被不断地开发与完善.深入理解充放电过程中锂电池内部电极/电解质界面的电化学过程以及微观反应机理,有利于指导电池材料的优化设计.原位电化学原子力显微镜将原子力显微镜的高分辨表界面分析优势与电化学反应装置相结合,能够在电池运行条件下实现对电极/电解质界面的原位可视化研究,并进一步从纳米尺度上揭示界面结构的演化规律与动力学过程.本文总结了原位电化学原子力显微镜在锂电池电极过程中的最新研究进展,主要包括基于转化型反应的正极过程、固体电解质中间相的动态演化以及固态电池界面演化与失效分析.