测定微电极表面的物质浓度：研究固定态和渐变态下的物质传递

论文摘要

在实验室已建立的有关电极迁移层内电活性物质的自发对流和迁移作用的模型的基础上,我们进一步研究了电极迁移层内各种物质传递的方式:线性迁移,非平面迁移,电泳,自发对流和由浓度梯度引发的对流等各自的作用。所采用的实验方法是使用超微电极稳态安培法测定稳态和暂态电化学过程中,电极迁移层内的浓度曲线。当有自发对流发生时,所得实验结果与相对应的理论预测行为比较相符。我们定义了该理论模型在研究由浓度梯度引发的对流时的缺陷。当前的工作也为在酶修饰电极迁移层内测定浓度曲线提供了可行性,这里我们只显示这项工作的第一部分,也就是有关酶电极的制作方法。

论文目录

• 英文摘要
• 摘要
• ACKNOWLEDGMENTS
• 致谢
• 详细摘要
• 论文概述
• General introduction
• Part I Bibliography
• 1. Introduction
• 2. Mass transport
• 2.1 General introduction about mass transport
• 2.2 Recent advancements in the study of mass transport
• Mass transport in microfluidic systems and 1ab-on-chips
• Mass transport in polymers
• Mass transport in biological and pharmaceutical areas
• 3. Establishment of concentration profiles
• 3.1 Evolution of concentration profiles
• 3.2 Techniques of establishing concentration profiles
• 3.2.1 Optical and spectroscopic methods
• Infrared spectroscopy
• Ultraviolet- visible （UV-visible） spectroscopy
• Raman spectroscopy
• The other techniques
• 3.2.2 Electrochemical methods
• Electrochemical detection with potentiometric mode
• Electrochemical detection in amperometric mode
• 4. Mapping concentration profiles with ultramicroelectrodes as local probes
• 4.1 About ultramicroelectrodes
• 4.1.1 Introduction of UMEs
• 4.1.2 Advantages of UMEs and their applications
• Advantages of UMEs
• Applications of UMEs
• 4.2 UMEs in amperometric mode as local probes
• 4.2.1 Controlled amperometric detection
• 4.2.2 Steady state amperometric detection
• 5. Conclusion
• Part II Applications of mapping concentration profiles on the study of the role of spontaneous convection in mass transport
• 1. Introduction
• 2. Model describing the contribution of spontaneous convectionto mass transport
• 2.1 Establishment of the model
• 2.1.1 Nernst diffusion layer model
• 2.1.2 Introduction of fluid particles and spatial-dependent Dconv
• 2.1.3 General equation of mass transport with diffusion / convection in one direction
• 2.1.4 Evolution of the diffusion coefficient Dconv as a function of space
• 2.1.5 Introduction of the apparent diffusion coefficient Dapp
• 2.2 Steady state diffusion imposed by spontaneous convection
• 2.2.1 Value of the convection layer thickness
• 2.2.2 Expression of the steady state concentration profile
• 2.3 Transition from transient diffusion to steady state diffusion
• 2.4 Competition between spontaneous convection and non-planar diffusion for the accomplishment of the steady state
• 3 Study of the role of spontaneous convection during cyclic voltammetry
• 3.1 Theory
• 3.2 Experimental
• 3.2.1 Concentration profiles mapped at different potentials during cyclic voltammetry
• 3.2.2 Cyclic voltammograms at different scan rates
• 4 Competition between spontaneous convection and non-planar diffusion
• 4.1 Theory
• 4.1.1 Steady-state. regimes
• Steady state with pure diffusion
• Steady state controlled by spontaneous convection
• Isoconcentration lines on the surface of the electrode
• 4.1.2 Elaboration of a zone diagram
• 4.1.3 Diagram describing the transitions between the different zones
• Transition between convection and diffusion
• Other transitions
• Diagram describing the transitions between the different zones
• 4.2 Experimental concentration profiles
• 5 Discussion and conclusion
• Part III Study of density gradients inducing convection through mapping concentrations profiles in the diffusion layer of an electrode
• 1. Introduction
• 2. Theory
• Contribution of density gradients inducing convection to mass transport
• 3. Experimental
• 3.1 About the experimental setup
• 3.2 Study of chronoamperometric behaviours with only spontaneous convection and diffusion as the forms of mass transport
• Transient chronoamperometric behaviours as the function of the electrode size
• 3.3 Study of density gradients inducing convection
• 3.3.1 Effects of density gradients inducing convection on the chronoamperometric currents
• 3.3.2 Study of the effects of the density gradients inducing convection through the model of spontaneous convection and diffusion
• layer'>Evolution of the diffusion layer thickness δ_layer
• app)'>Evolution of the diffusion layer thickness estimated from the current (δ_app)
• layer^stat and δ _conv^' estimated from δ_app^stat'>Comparison between the convection layer thickness 5conv estimated from δ_layer^stat and δ _conv^' estimated from δ_app^stat
• 4. Conclusion
• Part IV Study of the contributions of migration and spontaneous convection to mass transport through monitoring steady state concentration profiles in the diffusion layer of an electrode
• 1. Introduction
• 2. Establishment of theoretical concentration profiles
• 2.1 Mass transport with diffusion,migration and convection
• 2.1.1 Equations of mass transport with diffusion, migration and convection
• 2.1.2 Resolution of the mass transport equations
• Introduction of dimensionless parameters
• Boundary conditions
• Steady state concentration profiles
• 2.2 Tracing steady state concentration profiles
• 2.2.1 Reduction of a neutral species with （z, n） being equal to（0,+1）
• 2.2.2 Oxidation of a species A+ with （z, n） as （+1, -1）
• 3. Experimental concentration profiles
• z+ and B^（z-n）+ on the UME probes'>3.1 Experimental currents of A^z+ and B^（z-n）+ on the UME probes
• 3.2 Experimental concentration profiles
• 3.2.1 Reduction of Tetracyanoquinodimethane （TCNQ） as （z,n） = （0,+1）
• 3.2.2 Oxidation of （Ferrocenylmethyl） trimethylammonium hexafluorophosphate （FcNMe3+, PF6-）
• 4. Conclusion
• Part V Mapping concentration profiles in the diffusion layer of an enzyme-modified electrode: 1. fabrication of enzyme-modified electrodes.
• 1. Introduction
• 2. Mechanism of the chemical polymerisation
• 3. Experimental
• 3.1 Chemicals and reagents
• 3.2 Electrode fabrication
• 3.3 Measurements
• 4. Results and discussion
• 4.1 Time dependence of the polymerization and Pt nanoparticles deposition
• 4.2 Characterization of GOD/Pt/PPy electrode
• 4.3 Electrochemical methods to characterize GOD/Pt/PPy electrode in comparison with GOD/PPy electrode and GOD electrode
• 4.4 Reproducibility and stability of the GOD/Pt/PPy electrode
• 5. Conclusions
• General conclusion
• Appendix Experimental
• A1. Chemicals
• A1.1 Electroactive reactants
• A1.2 Supporting electrolytes
• A1.3 Solvents
• A2. Electrodes fabrication
• A2.1 Fabrication of a classical electrode
• A2.2 UME fabrication and characterization
• A2.2.1 UME fabrication
• A2.2.2 UME characterization
• A3. Experimental setup and procedures
• A3.1. Experimental setup and procedure in diluted solutions
• A3.2. Experimental setup and procedure in concentrated solutions
• A4 Experimental conditions
• A4.1 Experimental conditions for "concentration profiles mapped at different potentials during cyclic voltammetry " （Part.II.3.2.1）
• A4.2 Experimental conditions for" Cyclic voltammtries at different scan rates to study the effects of spontaneous convection "（Part.II.3.2.2）
• A4.3 Experimental conditions for "Competition between spontaneous convection and non-planar diffusion "（Part.II.4.2）)
• A4.4 Experimental conditions for "Study of density gradients inducing convection through mapping concentrations profiles in the diffusion layer of an electrode "（Part.III. 3）
• A4.5 Experimental conditions for "Reduction of Tetracyanoquinodimethane （TCNQ） as （z, n） = （0, +1） " （Part.IV.3.2.1）
• A4.6 Experimental conditions for "Oxidation of （Ferrocenylmethyl）-trimethylammonium hexafluorophosphate （FcNMe3+, PF6-）"（Part.IV.3.2.2）
• Appendix Program. Simulations of steady state concentration profiles in the diffusion layer of different-sized electrodes
• References