Other affiliations: Rockwell International
Bio: Florian Mansfeld is an academic researcher from University of Southern California. The author has contributed to research in topics: Corrosion & Dielectric spectroscopy. The author has an hindex of 64, co-authored 249 publications receiving 15368 citations. Previous affiliations of Florian Mansfeld include Rockwell International.
Papers published on a yearly basis
TL;DR: In this article, a discussion of the requirements for hardware and software necessary for collection and analysis of electrochemical impedance spectroscopy data for polymer coated metals is presented, where the authors show that a simple model can describe the frequency dependence of impedance spectra for polymer-coated metals exposed to corrosive environments.
Abstract: A discussion of the requirements for hardware and software necessary for collection and analysis of electrochemical impedance spectroscopy data for polymer coated metals is presented. Most authors agree that a simple model can describe the frequency dependence of impedance spectra for polymer coated metals exposed to corrosive environments. The water uptake of the coating can be estimated from the time dependence of the coating capacitance C c, The pore resistance R po depends both on the resistivity ρ of the coating and the disbonded area A d. The polarization resistance R P of the corroding area under the coating and the corresponding capacitance C dl both depend on A d. The breakpoint frequency method is discussed in detail and the dependence of the breakpoint frequency f b on ρ and A d is derived. In addition to f b other parameters can be obtained which depend on the ratio A d/ρ or only on A d or ρ. Since these parameters can be obtained at frequencies exceeding 1 Hz without the need for an analysis of the impedance spectra in the entire frequency region, this approach is considered especially useful for corrosion monitoring. The concepts proposed for the analysis and interpretation of EIS data for polymer coated metals are illustrated using data for Al alloys, Mg and steel exposed to NaCl. For an alkyd coating on cold rolled steel the time dependence of A d and ρ during exposure to 0.5 m NaCl has been determined qualitatively using the modified breakpoint frequency method.
TL;DR: In this paper, the authors used Electrochemical impedance spectroscopy (EIS) to study the internal resistance of microbial fuel cells (MFCs), electrode materials, catalyst coatings on electrodes, biofilm development and electrochemical reactions on the anodes and the cathodes of MFCs.
Abstract: Electrochemical impedance spectroscopy (EIS) is a powerful nondestructive technique that can act as a beneficial addition to the current techniques for studying microbial fuel cells (MFCs). Its application in MFC research should be further explored in the analysis of the internal resistance of MFCs, electrode materials, catalyst coatings on electrodes, biofilm development and electrochemical reactions on the anodes and the cathodes of MFCs.
TL;DR: In this paper, a brief review is given of DC and AC techniques which can be used to determine corrosion rates, and the advantages and disadvantages of the extrapolation method of Tafel lines, polarization resistance measurements and impedance measurements are discussed.
Abstract: A brief review is given of DC and AC techniques which can be used to determine corrosion rates. The advantages and disadvantages of the extrapolation method of Tafel lines, polarization resistance measurements and impedance measurements are discussed. In particular it is shown that the intercept of the capacitive impedance loop with the real axis of the complex impedance diagram does not correspond to the charge transfer resistance of complicated corrosion systems exhibiting several time constants in the capacitive and inductive loop(s). Therefore, the correlation between this intercept value and the corrosion rate is not generally valid. Experimental data are presented for two types of iron (Marz and Johnson-Matthey) and 4340 steel in de-aerated and aerated 0.5 M H2SO4 and 1 M HCl in the absence and presence of the following inhibitors: triphenylbenzylphosphonium-chloride (TPBP+), propargylic alcohol (PA), 2-butyne-1,4 diol (BD) and hexynol (H). Corrosion rates have been determined by applying DC and AC measurements and solution analysis by atomic absorption. The results, in the absence of inhibitors and in the presence of TPBP+, show that the corrosion rate is unequivocally correlated to electrochemical DC data and to the extrpolated value of the inductive loop of AC measurements to zero frequency. However, in systems containing the other inhibitors the corrosion rate cannot be correlated to the polarization resistance because of an irreversible desorption of the inhibitor in the close vicinity of the corrosion potential, which gives an unpolarizable behaviour of the system in the anodic range. The relatively low inhibition efficiencies in the presence of PA and BD can be explained by a superimposed fast electrochemical reduction of the additives. Moreover, it is shown that the inhibition efficiency depends on the hydrodynamic conditions. The results of these investigations show that electrochemical DC and AC techniques can successfully be applied for determination of metal corrosion rates in systems that have simple corrosion kinetics. In more complicated systems knowledge of the details of the mechanism is necessary for interpretation of the experimental data.
University of Southern California1, Rice University2, Korea Institute of Science and Technology3, Gwangju Institute of Science and Technology4, J. Craig Venter Institute5, Pacific Northwest National Laboratory6, University of Oklahoma7, Oak Ridge National Laboratory8, University of Wisconsin–Milwaukee9
TL;DR: The results showed that a few key cytochromes play a role in all of the processes but that their degrees of participation in each process are very different, suggesting a very complex picture of electron transfer to solid and soluble substrates by S. oneidensis MR-1.
Abstract: Shewanella oneidensis MR-1 is a gram-negative facultative anaerobe capable of utilizing a broad range of electron acceptors, including several solid substrates. S. oneidensis MR-1 can reduce Mn(IV) and Fe(III) oxides and can produce current in microbial fuel cells. The mechanisms that are employed by S. oneidensis MR-1 to execute these processes have not yet been fully elucidated. Several different S. oneidensis MR-1 deletion mutants were generated and tested for current production and metal oxide reduction. The results showed that a few key cytochromes play a role in all of the processes but that their degrees of participation in each process are very different. Overall, these data suggest a very complex picture of electron transfer to solid and soluble substrates by S. oneidensis MR-1.
04 Apr 2005
Abstract: Preface. Preface to the First Edition. Contributors. Contributors to the First Edition. Chapter 1. Fundamentals of Impedance Spectroscopy (J.Ross Macdonald and William B. Johnson). 1.1. Background, Basic Definitions, and History. 1.1.1 The Importance of Interfaces. 1.1.2 The Basic Impedance Spectroscopy Experiment. 1.1.3 Response to a Small-Signal Stimulus in the Frequency Domain. 1.1.4 Impedance-Related Functions. 1.1.5 Early History. 1.2. Advantages and Limitations. 1.2.1 Differences Between Solid State and Aqueous Electrochemistry. 1.3. Elementary Analysis of Impedance Spectra. 1.3.1 Physical Models for Equivalent Circuit Elements. 1.3.2 Simple RC Circuits. 1.3.3 Analysis of Single Impedance Arcs. 1.4. Selected Applications of IS. Chapter 2. Theory (Ian D. Raistrick, Donald R. Franceschetti, and J. Ross Macdonald). 2.1. The Electrical Analogs of Physical and Chemical Processes. 2.1.1 Introduction. 2.1.2 The Electrical Properties of Bulk Homogeneous Phases. 184.108.40.206 Introduction. 220.127.116.11 Dielectric Relaxation in Materials with a Single Time Constant. 18.104.22.168 Distributions of Relaxation Times. 22.214.171.124 Conductivity and Diffusion in Electrolytes. 126.96.36.199 Conductivity and Diffusion-a Statistical Description. 188.8.131.52 Migration in the Absence of Concentration Gradients. 184.108.40.206 Transport in Disordered Media. 2.1.3 Mass and Charge Transport in the Presence of Concentration Gradients. 220.127.116.11 Diffusion. 18.104.22.168 Mixed Electronic-Ionic Conductors. 22.214.171.124 Concentration Polarization. 2.1.4 Interfaces and Boundary Conditions. 126.96.36.199 Reversible and Irreversible Interfaces. 188.8.131.52 Polarizable Electrodes. 184.108.40.206 Adsorption at the Electrode-Electrolyte Interface. 220.127.116.11 Charge Transfer at the Electrode-Electrolyte Interface. 2.1.5 Grain Boundary Effects. 2.1.6 Current Distribution, Porous and Rough Electrodes- the Effect of Geometry. 18.104.22.168 Current Distribution Problems. 22.214.171.124 Rough and Porous Electrodes. 2.2. Physical and Electrochemical Models. 2.2.1 The Modeling of Electrochemical Systems. 2.2.2 Equivalent Circuits. 126.96.36.199 Unification of Immitance Responses. 188.8.131.52 Distributed Circuit Elements. 184.108.40.206 Ambiguous Circuits. 2.2.3 Modeling Results. 220.127.116.11 Introduction. 18.104.22.168 Supported Situations. 22.214.171.124 Unsupported Situations: Theoretical Models. 126.96.36.199 Unsupported Situations: Equivalent Network Models. 188.8.131.52 Unsupported Situations: Empirical and Semiempirical Models. Chapter 3. Measuring Techniques and Data Analysis. 3.1. Impedance Measurement Techniques (Michael C. H. McKubre and Digby D. Macdonald). 3.1.1 Introduction. 3.1.2 Frequency Domain Methods. 184.108.40.206 Audio Frequency Bridges. 220.127.116.11 Transformer Ratio Arm Bridges. 18.104.22.168 Berberian-Cole Bridge. 22.214.171.124 Considerations of Potentiostatic Control. 126.96.36.199 Oscilloscopic Methods for Direct Measurement. 188.8.131.52 Phase-Sensitive Detection for Direct Measurement. 184.108.40.206 Automated Frequency Response Analysis. 220.127.116.11 Automated Impedance Analyzers. 18.104.22.168 The Use of Kramers-Kronig Transforms. 22.214.171.124 Spectrum Analyzers. 3.1.3 Time Domain Methods. 126.96.36.199 Introduction. 188.8.131.52 Analog-to-Digital (A/D) Conversion. 184.108.40.206 Computer Interfacing. 220.127.116.11 Digital Signal Processing. 3.1.4 Conclusions. 3.2. Commercially Available Impedance Measurement Systems (Brian Sayers). 3.2.1 Electrochemical Impedance Measurement Systems. 18.104.22.168 System Configuration. 22.214.171.124 Why Use a Potentiostat? 126.96.36.199 Measurements Using 2, 3 or 4-Terminal Techniques. 188.8.131.52 Measurement Resolution and Accuracy. 184.108.40.206 Single Sine and FFT Measurement Techniques. 220.127.116.11 Multielectrode Techniques. 18.104.22.168 Effects of Connections and Input Impedance. 22.214.171.124 Verification of Measurement Performance. 126.96.36.199 Floating Measurement Techniques. 188.8.131.52 Multichannel Techniques. 3.2.2 Materials Impedance Measurement Systems. 184.108.40.206 System Configuration. 220.127.116.11 Measurement of Low Impedance Materials. 18.104.22.168 Measurement of High Impedance Materials. 22.214.171.124 Reference Techniques. 126.96.36.199 Normalization Techniques. 188.8.131.52 High Voltage Measurement Techniques. 184.108.40.206 Temperature Control. 220.127.116.11 Sample Holder Considerations. 3.3. Data Analysis (J. Ross Macdonald). 3.3.1 Data Presentation and Adjustment. 18.104.22.168 Previous Approaches. 22.214.171.124 Three-Dimensional Perspective Plotting. 126.96.36.199 Treatment of Anomalies. 3.3.2 Data Analysis Methods. 188.8.131.52 Simple Methods. 184.108.40.206 Complex Nonlinear Least Squares. 220.127.116.11 Weighting. 18.104.22.168 Which Impedance-Related Function to Fit? 22.214.171.124 The Question of "What to Fit" Revisited. 126.96.36.199 Deconvolution Approaches. 188.8.131.52 Examples of CNLS Fitting. 184.108.40.206 Summary and Simple Characterization Example. Chapter 4. Applications of Impedance Spectroscopy. 4.1. Characterization of Materials (N. Bonanos, B. C. H. Steele, and E. P. Butler). 4.1.1 Microstructural Models for Impedance Spectra of Materials. 220.127.116.11 Introduction. 18.104.22.168 Layer Models. 22.214.171.124 Effective Medium Models. 126.96.36.199 Modeling of Composite Electrodes. 4.1.2 Experimental Techniques. 188.8.131.52 Introduction. 184.108.40.206 Measurement Systems. 220.127.116.11 Sample Preparation-Electrodes. 18.104.22.168 Problems Associated With the Measurement of Electrode Properties. 4.1.3 Interpretation of the Impedance Spectra of Ionic Conductors and Interfaces. 22.214.171.124 Introduction. 126.96.36.199 Characterization of Grain Boundaries by IS. 188.8.131.52 Characterization of Two-Phase Dispersions by IS. 184.108.40.206 Impedance Spectra of Unusual Two-phase Systems. 220.127.116.11 Impedance Spectra of Composite Electrodes. 18.104.22.168 Closing Remarks. 4.2. Characterization of the Electrical Response of High Resistivity Ionic and Dielectric Solid Materials by Immittance Spectroscopy (J. Ross Macdonald). 4.2.1 Introduction. 4.2.2 Types of Dispersive Response Models: Strengths and Weaknesses. 22.214.171.124 Overview. 126.96.36.199 Variable-slope Models. 188.8.131.52 Composite Models. 4.2.3 Illustration of Typical Data Fitting Results for an Ionic Conductor. 4.3. Solid State Devices (William B. Johnson and Wayne L. Worrell). 4.3.1 Electrolyte-Insulator-Semiconductor (EIS) Sensors. 4.3.2 Solid Electrolyte Chemical Sensors. 4.3.3 Photoelectrochemical Solar Cells. 4.3.4 Impedance Response of Electrochromic Materials and Devices (Gunnar A. Niklasson, Anna Karin Johsson, and Maria Stromme). 184.108.40.206 Introduction. 220.127.116.11 Materials. 18.104.22.168 Experimental Techniques. 22.214.171.124 Experimental Results on Single Materials. 126.96.36.199 Experimental Results on Electrochromic Devices. 188.8.131.52 Conclusions and Outlook. 4.3.5 Time-Resolved Photocurrent Generation (Albert Goossens). 184.108.40.206 Introduction-Semiconductors. 220.127.116.11 Steady-State Photocurrents. 18.104.22.168 Time-of-Flight. 22.214.171.124 Intensity-Modulated Photocurrent Spectroscopy. 126.96.36.199 Final Remarks. 4.4. Corrosion of Materials (Digby D. Macdonald and Michael C. H. McKubre). 4.4.1 Introduction. 4.4.2 Fundamentals. 4.4.3 Measurement of Corrosion Rate. 4.4.4 Harmonic Analysis. 4.4.5 Kramer-Kronig Transforms. 4.4.6 Corrosion Mechanisms. 188.8.131.52 Active Dissolution. 184.108.40.206 Active-Passive Transition. 220.127.116.11 The Passive State. 4.4.7 Point Defect Model of the Passive State (Digby D. Macdonald). 18.104.22.168 Introduction. 22.214.171.124 Point Defect Model. 126.96.36.199 Electrochemical Impedance Spectroscopy. 188.8.131.52 Bilayer Passive Films. 4.4.8 Equivalent Circuit Analysis (Digby D. Macdonald and Michael C. H. McKubre). 184.108.40.206 Coatings. 4.4.9 Other Impedance Techniques. 220.127.116.11 Electrochemical Hydrodynamic Impedance (EHI). 18.104.22.168 Fracture Transfer Function (FTF). 22.214.171.124 Electrochemical Mechanical Impedance. 4.5. Electrochemical Power Sources. 4.5.1 Special Aspects of Impedance Modeling of Power Sources (Evgenij Barsoukov). 126.96.36.199 Intrinsic Relation Between Impedance Properties and Power Sources Performance. 188.8.131.52 Linear Time-Domain Modeling Based on Impedance Models, Laplace Transform. 184.108.40.206 Expressing Model Parameters in Electrical Terms, Limiting Resistances and Capacitances of Distributed Elements. 220.127.116.11 Discretization of Distributed Elements, Augmenting Equivalent Circuits. 18.104.22.168 Nonlinear Time-Domain Modeling of Power Sources Based on Impedance Models. 22.214.171.124 Special Kinds of Impedance Measurement Possible with Power Sources-Passive Load Excitation and Load Interrupt. 4.5.2 Batteries (Evgenij Barsoukov). 126.96.36.199 Generic Approach to Battery Impedance Modeling. 188.8.131.52 Lead Acid Batteries. 184.108.40.206 Nickel Cadmium Batteries. 220.127.116.11 Nickel Metal-hydride Batteries. 18.104.22.168 Li-ion Batteries. 4.5.3 Impedance Behavior of Electrochemical Supercapacitors and Porous Electrodes (Brian E. Conway). 22.214.171.124 Introduction. 126.96.36.199 The Time Factor in Capacitance Charge or Discharge. 188.8.131.52 Nyquist (or Argand) Complex-Plane Plots for Representation of Impedance Behavior. 184.108.40.206 Bode Plots of Impedance Parameters for Capacitors. 220.127.116.11 Hierarchy of Equivalent Circuits and Representation of Electrochemical Capacitor Behavior. 18.104.22.168 Impedance and Voltammetry Behavior of Brush Electrode Models of Porous Electrodes. 22.214.171.124 Impedance Behavior of Supercapacitors Based on Pseudocapacitance. 126.96.36.199 Deviations of Double-layer Capacitance from Ideal Behavior: Representation by a Constant-phase Element (CPE). 4.5.4 Fuel Cells (Norbert Wagner). 188.8.131.52 Introduction. 184.108.40.206 Alkaline Fuel Cells (AFC). 220.127.116.11 Polymer Electrolyte Fuel Cells (PEFC). 18.104.22.168 Solid Oxide Fuel Cells (SOFC). Appendix. Abbreviations and Definitions of Models. References. Index.
TL;DR: In this paper, the state of the art in coating and surface modification technologies, applied to magnesium-based substrates for improved corrosion and wear resistance, are discussed, including electrochemical plating, conversion coatings, anodizing, gas phase deposition processes, laser surface alloying/cladding and organic coatings.
Abstract: Magnesium and its alloys have excellent physical and mechanical properties for a number of applications. In particular its high strength:weight ratio makes it an ideal metal for automotive and aerospace applications, where weight reduction is of significant concern. Unfortunately, magnesium and its alloys are highly susceptible to corrosion, particularly in salt-spray conditions. This has limited its use in the automotive and aerospace industries, where exposure to harsh service conditions is unavoidable. The simplest way to avoid corrosion is to coat the magnesium-based substrate to prevent contact with the environment. This review details the state of the art in coating and surface modification technologies, applied to magnesium based substrates for improved corrosion and wear resistance. The topics covered include electrochemical plating, conversion coatings, anodizing, gas-phase deposition processes, laser surface alloying/cladding and organic coatings.
TL;DR: This Progress article explores the underlying reasons for exocellular electron transfer, including cellular respiration and possible cell–cell communication, to understand bacterial versatility in mechanisms used for current generation.
Abstract: The use of microbial fuel cells to generate electrical current is increasingly being seen as a viable source of renewable energy production In this Progress article, Bruce Logan highlights recent advances in our understanding of the mechanisms used by exoelectrogenic bacteria to generate electrical current and the important factors to consider in microbial fuel cell design There has been an increase in recent years in the number of reports of microorganisms that can generate electrical current in microbial fuel cells Although many new strains have been identified, few strains individually produce power densities as high as strains from mixed communities Enriched anodic biofilms have generated power densities as high as 69 W per m2 (projected anode area), and therefore are approaching theoretical limits To understand bacterial versatility in mechanisms used for current generation, this Progress article explores the underlying reasons for exocellular electron transfer, including cellular respiration and possible cell–cell communication
TL;DR: The various substrates that have been explored in MFCs so far, their resulting performance, limitations as well as future potential substrates are reviewed.
Abstract: Microbial fuel cells (MFCs) have gained a lot of attention in recent years as a mode of converting organic waste including low-strength wastewaters and lignocellulosic biomass into electricity Microbial production of electricity may become an important form of bioenergy in future because MFCs offer the possibility of extracting electric current from a wide range of soluble or dissolved complex organic wastes and renewable biomass A large number of substrates have been explored as feed The major substrates that have been tried include various kinds of artificial and real wastewaters and lignocellulosic biomass Though the current and power yields are relatively low at present, it is expected that with improvements in technology and knowledge about these unique systems, the amount of electric current (and electric power) which can be extracted from these systems will increase tremendously providing a sustainable way of directly converting lignocellulosic biomass or wastewaters to useful energy This article reviews the various substrates that have been explored in MFCs so far, their resulting performance, limitations as well as future potential substrates