Electrochemistry, Materials

Our research is in the general area of electrochemical science, with particular interests in analytical and physical electrochemistry and the science of materials and interfaces. Previous work has focused on the theory and application of microelectrodes, electrodes which have at least one dimension on the order of micrometers or smaller. Microelectrodes make possible a number of electrochemical measurements that are difficult or impossible with conventional electrodes (of millimeter dimension). For example, a microelectrode can be used to perform voltammetry in a highly resistive medium such as a supercritical fluid. Microelectrodes also display enhanced mass transfer on the typical electrochemical time scale, a feature which can be exploited in the design of electrochemical sensors having improved sensitivity. Microelectrodes having a high perimeter (edge)-to-area ratio (for example, microband or microring electrodes) are particularly useful in this regard, since current density increases as the perimeter-to-area ratio increases. Electrically conducting composite materials fabricated by incorporating a conducting powder (e.g., graphite, silver, gold, or platinum) into an insulating polymer matrix (e.g., poly(chlorotrifluoroethylene) or PCTFE) represent a highly versatile approach to microelectrode ensemble fabrication and design. Bulk modifiers which enhance selectivity or sensitivity toward a target species may be incorporated directly into the composite material. Such composites based on PCTFE are chemically and mechanically robust, machinable, and typically contain only ca. 10% conductor by volume.

More recently, our work has focused on the electrochemistry of corrosion, with four main goals: 1) investigation of active coatings for corrosion control; 2) understanding corrosion mechanisms, particularly at metal substrate/coating interfaces; 3) development of sensors for early detection of coating failure and/or corrosion onset; and 4) probing electrical and electrochemical properties of metal alloy surfaces.  This work, in collaboration with Professor Gordon Bierwagen of the Coatings and Polymeric Materials Department, utilizes a variety of techniques to study corrosion and the mechanisms by which active coatings alter the corrosion behavior.  We define active coatings as coatings that consist of (or contain) components that interact electrically and/or electrochemically with the active metal to be protected (e.g., Fe or Al alloys).  Examples of active coatings studied in our laboratory include conjugated polymer coatings and magnesium-rich coatings for the protection of Al alloys. 

Among the techniques currently used in our laboratory for the study of corrosion at coated metal substrates are global techniques (such as electrochemical noise measurements and electrochemical impedance spectroscopy) as well as a variety of scanning probe techniques that provide spatial (or local) as well as temporal information about the corrosion process.  These scanning probe techniques include the scanning vibrating electrode technique (SVET, for current density mapping), the scanning ion electrode technique (SIET, especially for pH mapping), the scanning polarographic electrode technique (SPET, for oxygen mapping), local electrochemical impedance spectroscopy/mapping (LEIS/LEIM), scanning electrochemical microscopy (SECM, for probing electron transfer at surfaces), electrochemical atomic force microscopy (AFM and ECAFM) and conducting or current sensing AFM (C-AFM, for studying the conductivity of materials at the micrometer and nanometer scale).  Studies using these scanning probe techniques are complemented by measurements employing scanning electron microscopy (SEM, combined with energy dispersive x-ray analysis) and x-ray photoelectron spectroscopy (XPS).  Together, these techniques provide a rather complete view of the corrosion process and the manner in which it is altered by active corrosion control coatings.

Figure 1. Left - a scanning vibrating electrode (SVET) instrument, showing control computer, monitors, electronics rack and air table containing micropositioner, cell and video microscope. Right – a current density map for an aluminum alloy (AA 2024-T3) at 20 minutes immersion in dilute Harrison’s solution (0.35% (NH4)2SO4 and 0.05% NaCl) showing local anodic (positive) and cathodic (negative) currents.

Figure 2. Left - a scanning electrochemical microscope (SECM) instrument, showing control electronics, micropositioner, cell and video microscope. Right – a SECM map showing an active region for reduction on AA 2024-T3 using 0.01 M hydroquinone as mediator (in 1.0 M Na2SO4, 0.005 M H2SO4; Eprobe = 1 V, Esubstrate = open circuit potential).

Selected Publications

K. Allahar, Dante Battocchi, Mark E. Orazem, Gordon P. Bierwagen and Dennis E. Tallman, “Transmission Line Modeling of Electrochemical Impedance Spectroscopic Data of a Magnesium Rich Primer,” Electrochimica Acta (2009) in press.

J.M. Gustavsson, P.C. Innis, J. He, G.G. Wallace and D.E. Tallman, “Processible Polyaniline-HCSA/poly(Vinyl Acetate-co-Butyl Acrylate) Corrosion Protection Coatings for AA2024-T3: A SVET and Raman study,” Electrochimica Acta (2009) in press.

Brian R. Hinderliter, Kerry N. Allahar, Gordon P. Bierwagen, Dennis E. Tallman, and Stuart G. Croll, “Water Sorption and Diffusional Properties of a Cured Epoxy Resin Measured using Alternating Ionic Liquids/ Aqueous Electrolytes in Electrochemical Impedance Spectroscopy, Journal of Coatings Technology and Research 5(4) (2008) 431-438.

K. L. Levine, D. E. Tallman and G. P. Bierwagen, “Mott-Schottky Analysis of Aluminium Oxide Formed in the Presence of Different Mediators on the Surface of Aluminium Alloy 2024-T3,” Journal of Materials Processing Technology 199(1-3) (2008)  321-326.

B. R. Hinderliter, K. N. Allahar, G. P. Bierwagen, D. E. Tallman, and S. G. Croll, “Thermal Cycling of Epoxy Coatings using Room Temperature Ionic Liquids,” Journal of the Electrochemical Society 155 (2008) C93-C100.

K. N. Allahar, B. R. Hinderliter, , G. P. Bierwagen, D. E. Tallman, and S. G. Croll, “Cyclic Wet Drying of an Epoxy Coating using an Ionic Liquid,” Progress in Organic Coatings  62 (2008) 87-95.

K. N. Allahar, B. R. Hinderliter, D. E. Tallman and G. P. Bierwagen, “Water Transport in Multilayer Organic Coatings,” ECS Transactions 6(24) (2008) 41-55.

Dennis E. Tallman, Kirill L. Levine, Chavanin Siripirom, Victoria Gelling, Gordon P. Bierwagen, and Stuart G. Croll, “Nanocomposite of Polypyrrole and Alumina Nanoparticles as a Coating Filler for the Corrosion Protection of Aluminium Alloy 2024-T3, Applied Surface Science 254 (2008) 5452–5459.

Mark B. Jensen, Audrey Guerard, Dennis E. Tallman, and Gordon P. Bierwagen, “Studies of Electron Transfer at Aluminum Alloy Surfaces by Scanning Electrochemical Microscopy,” Journal of the Electrochemical Society 155 (2008) C324-C332.

Kerry Allahar, Brian Hinderliter, Dennis Tallman and Gordon Bierwagen, “Water Transport in Multilayer Organic Coatings,” Journal of the Electrochemical Society 155 (2008) F201-F208.

J. Nie, D. E. Tallman and G. P. Bierwagen, “The Electrodeposition of Polypyrrole on Al Alloy from Room Temperature Ionic Liquids,” Journal of Coatings Technology and Research 5(3) (2008) 327-334.

Gordon Bierwagen, Kerry Allahar, Brian Hinderliter, Alda Simoes, Dennis Tallman and Stuart Croll, “Ionic Liquid Enhanced Electrochemical Characterization of Organic Coatings,” Progress in Organic Coatings 63 (2008) 250-259.

Kerry Allahar, Dante Battocchi, Mark Orazem, Gordon Bierwagen, and Dennis Tallman, "Modeling of Electrochemical Impedance Data of a Magnesium-Rich Primer," Journal of the Electrochemical Society 155(10) (2008) E143-E149.
Alda Simoes, Dante Battocchi, Dennis Tallman, Gordon Bierwagen, “Assessment of the Corrosion Protection of Aluminium Substrates by a Mg-rich Primer: EIS, SVET and SECM Study,” Progress in Organic Coatings  63(3) (2008) 260-266.

Maocheng Yan, Dennis E. Tallman, and Gordon P. Bierwagen, “Role of Oxygen in the Galvanic Interaction between Polypyrrole and Aluminum Alloy,” Electrochimica Acta 54(2) (2008) 220-227.

Dennis E. Tallman and Gordon P. Bierwagen, “Corrosion Protection Using Conducting Polymers,” Chapter 15 in Handbook of Conducting Polymers, Third Edition,: Conjugated Polymers-Processing and Applications, CRC Press (2007) pp. 15-1 to 15-53.

K.N. Allahar, B. Hinderliter, A.M. Simoes, D.E. Tallman, G.P Bierwagen and S.G. Croll, “Simulation of Wet-Dry Cycling of Organic Coatings using Ionic Liquids,” ECS Transactions 2(14) (2007) 31-48.

P. Zarras, J. He, D. E. Tallman, N. Anderson, A. Guenthner, C. Webber, J. D. Stenger-Smith, J. M. Pentony, S. Hawkins and L. Baldwin, “Electroactive Polymer Coatings as Replacements for Chromate Conversion Coatings,” ACS Symposium Series,  957(Smart Coatings) (2007) 135-151.

Christopher L. Heth, Scott D. Rothstein, Dennis E. Tallman and Seth C. Rasmussen, “Poly(N-alkylaminothiophene)s: Heteroatomic Analogues of Polyoxothiophenes or an Unique New Class of Polythiophenes?,” Polymer Preprints 48(1) (2007) 95-96.

Gordon Bierwagen, Dante Battocchi, Alda Simões, Anthony Stamness and Dennis Tallman, “The Use of Multiple Electrochemical Techniques to Characterize Mg-rich Primers for Al Alloys,” Progress in Organic Coatings 59(3) (2007) 172-178.

Jie He, Dante Battocchi, Alda M. Simões, Dennis E. Tallman and Gordon P. Bierwagen, "Scanning Probe Studies of Active Coatings for Corrosion Control of Al Alloys" in New Developments in Coatings Technology, eds. Peter Zarras, Timothy Wood, Brough Richey and Brian C. Benicewicz, ACS Symposium Series 962 (New Developments in Coatings Technology), American Chemical Society, Washington DC, Chapter 2 (2007) 8-23. 

Dante Battocchi, Gordon Bierwagen, Anthony Stamness, Dennis Tallman and Alda Simões, “Mg-Rich Primer for Chromate Free Protective Systems on Al 2024 and Al 7075” in “Innovative Pre-Treatment Techniques to Prevent Corrosion of Metallic Surfaces, eds. L. Fedrizzi, H. Terryn and A. Simões, European Federation of Corrosion Publications Number 54, CRC Press, Chapter 5 (2007) 63-70.

A. M. Simões, D. Battocchi, D. E. Tallman and G. P. Bierwagen, “SVET and SECM Imaging of Cathodic Protection of Aluminium by a Mg-Rich Coating,” Corrosion Science 49(10) (2007) 3838-3849.

B. R. Hinderliter, K. N. Allahar, G. P. Bierwagen, D. E. Tallman, and S. G. Croll, “Thermal Cycling of Epoxy Coatings using Room Temperature Ionic Liquids,” ECS Transactions 3 (2007) 515-528.

Alda M. Simoes, Dante Battocchi, Dennis E. Tallman, and Gordon P. Bierwagen, “Corrosion Protection of Aluminium Substrates by a Mg-Rich Primer Studied using Electrochemical Scanning Techniques,” ICE 2007 (International Coatings Expo: Clean-Lean-Green: Innovative Solutions for the Global Coatings Community) (2007) 39/1-39/14.

K. N. Allahar, B. Hinderliter, A. M. Simoes, D. E. Tallman, G. P. Bierwagen, S. G. Croll, “Simulation of Wet-Dry Cycling of Organic Coatings using Ionic Liquids,” Journal of the Electrochemical Society 154 (2007) F177-F185.

M. B. Jensen, T. J. Bjordahl, D. E. Tallman and G. P. Bierwagen “Studies of Electron Transfer at Aluminum Alloy Surfaces by Scanning Electrochemical Microscopy”, ECS Transactions 3 (31) (2007) 545-555.

Dante Battocchi, Gordon P. Bierwagen, Anthony Stamness, Dennis E. Tallman and Alda Simoes, “Magnesium-Rich Primers for Chromate-Free Protective Systems on Al 2024 and Al 7075,” European Federation of Corrosion Publications 54(Innovative Pre-Treatment Techniques to Prevent Corrosion of Metallic Surfaces) (2007) 63-70.