MMA 900/910 : Configurations, Uses & Example Applications · • Up to 100 working electrodes (WE),...

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MMA 900/910 : Configurations, Uses & Example Applications

Scribner Associates, Inc.


Configurations


WE 1

A A A A A

2 3 N-1 N

CE

RE

Inter-electrode Current Polarized Cell Current

Configuration #1 – Electrode Arrays • Up to 100 working electrodes (WE), independent

current measurement for each channel • WEs galvanically coupled together • Common electrolyte • Common CE (optional) – required for polarized cell • Common RE (optional) – required to measure

potential of coupled array WEs • Polarize groups w.r.t. base potential (Eb) vs. RE • Polarize groups w.r.t. each other • At OCV, net I = 0 A (inter-electrode current only, no

current between WEs and CE) • Optional Configurations:

– Replace some WEs with REs for voltage mapping or ISEs (e.g., pH, X+/-) for chemical mapping

• Applications: – Interaction effects in corrosion (close spaced WE electrodes) – Localized corrosion (pitting statistics, crevice geometry) – Electroactive materials characterization – electrocatalysts,

electrode materials – Combinatorial electrochemistry and materials discovery – Sensors arrays

MMA 900/910

w.r.t. - with respect to


1

A

CE RE

Configuration #2 – Galvanic Couples • Up to 50 galvanic couple pairs • MMA is populated with 50 WE modules + 50

electrometer (i.e., RE) modules • Force WE = 0 V vs. CE/RE • For each cell: Metal #1 to unique WE/current

channel, metal #2 to common CE/RE input, RE to unique electrometer input

• Independent measurement of the galvanic current of each metal pair and the galvanic couple potential vs. RE

• Each couple in separate electrolyte, isolated from others

• Can apply voltage difference metal electrode pairs in groups of 10

• Applications: – Effect of material on galvanic corrosion – metal #1 and #2, surface

area – Effect of environment on galvanic corrosion – electrolyte

composition – Combinatorial chemistry – corrosion inhibitors, material screening

V

Metal #2 RE Metal #1

Pair #1 1

A V

Pair #2 1

A V

Pair #50

. . .

WEs REs

MMA 900/910


1

A

CE RE

Configuration #3 – Electrochemical Noise • Similar to configuration #2 except that all electrodes

are the same material • MMA is populated with 50 WE modules + 50

electrometer (i.e., RE) modules • Up to 50 galvanic couple pairs • For each cell: Electrode #1 to unique to WE/current

channel, #2 to common CE/RE input, Electrode #3 to unique electrometer input

• Force WE = 0 V vs. CE/RE • Independent measurement of the galvanic current of

each metal pair and the galvanic couple potential vs. RE

• Each couple in separate electrolyte, isolated from others

• Can apply voltage difference metal electrode pairs in groups of 10

• Optional Configurations: – Replace Electrode #3 with conventional RE so that the voltage

noise and current noise are correlated

• Applications: – High-throughput EN – materials characterization, statistical

significance – Effect of environment on EN

V

Cell #1 1

A V

Cell #2 1

A V

Cell #50

. . .

1 2 3

WEs REs

MMA 900/910


Experiment Types - MMALive™ • DC Experiments

– Open circuit – Potentiostatic – Potentiodynamic - linear sweep, cyclic voltammetry – Electrode pretreatment – Polarize groups of electrodes w.r.t. base potential (Eb) or other groups – Data analysis with MMAView

• Impedance Spectroscopy – OCV and at applied DC

potential – 10 kHz to 1 mHz – Analysis with ZView®


Examples of Customer Applications


Increasing ‘B’ Concentration

Increasing ‘A’ Concentration

Example of Heterogeneous Electrode Array

• Multi-segment WE or RE (or both) with composition or concentration gradient

• Applications:

– Fuel cell catalyst research – Battery electrode research – Biological and chemical sensors – Other combinatorial electrochemistry


Example of Heterogeneous Electrode Array • P. McGinn et. al. (U. of Notre Dame) use the MMA for

combinatorial screening of DMFC electrocatalysts • McGinn designed the array to suit their catalyst library

fabrication facility • McGinn & Scribner collaborated on the design of the

electrochemical cell; Scribner fabricated the cell

DMFC - direct methanol fuel cell

Appl. Surf. Sc. 254, 662 (2007) J. of Power Sources 163, 330 (2006)



J. of Power Sources 163, 330 (2006)



• Dahn et. al. (Dalhousie U.) use the MMA for combinatorial screening of battery electrodes materials

J. Electrochem. Soc. 150, A1465 (2003), J. Electrochem. Soc. 151, A1216 (2004), J. Electrochem. Soc. 151, A1628 (2004), Electrochem. Solid State Lett. 8, A137 (2005),


Example of Homogeneous Electrode Arrays

• Multi-segment Homogeneous Working Electrode to Simulate Monolithic Surface

• Applications: – Corrosion - localized anode and cathode

effects, pitting/crevicing, current and voltage mapping

– Effect of inclusions and precipitates, defects

– Coating failure analysis – Interaction effects – closely spaced

electrodes – Statistical analysis with wide electrode

spacing (non-interacting)

Close-spaced homogeneous

array

Wide-spaced electrode array

Close-spaced homogeneous array

with precipitate / defect



• J.R. Scully et. al. (U. of Virginia) use the MMA to study localized corrosion (pitting, crevicing)

• MEAs constructed from nominally identical electrodes or a combination of different materials to simulate compositional and structural heterogeneous surfaces

• Allow temporal and spatial measurements of electrochemical processes simultaneously

• Far-spaced arrays allow high-throughput experiments (e.g., pitting statistics such as distribution of breakdown potential); when interaction effects between electrodes is not wanted

• Closed-packed arrays simulate planar electrode and allow chemical and electrochemical coupling of electrodes

5x20 close-spaced MEA

5x5 far-spaced MEA

MEA – microelectrode array

J. Electrochem. Soc. 151, B233 (2004), Electrochem. Solid State Lett. 10, C16 (2007), ECS Trans. 3, 531 (2007)



Close-packed array of 100 AISI 316 SS electrodes

• Current maps demonstrate pitting & crevice corrosion • Pitting occurs randomly outside crevice

J. Electrochem. Soc. 151, B233 (2004), Electrochem. Solid State Lett. 10, C16 (2007), ECS Trans. 3, 531 (2007)



5x5 MEA of Al for chromate conversion coating

formation and breakdown

• Buchheit et. al. (Ohio State U.) use the MMA to study breakdown and pitting using MEAs made from nominally identical microelectrodes

• High-throughput testing allows for rapid measurement of meaningful statistics of stochastic corrosion processes

Electrochim. Acta 55, 7367 (2010), J. Electrochem. Soc. 149, B357 (2002)


Example of Galvanic Couples Configuration

Corrosion 61, 480 (2005)

• Taylor et. al. (U. Texas-Houston) uses the MMA for high-throughput screening for discovery of corrosion inhibitor synergies


Additional Information

• A datasheet for the MMA 900/910 is available at www.scribner.com/MMA

• A list of publications using MMA is available at

www.scribner.com/MMA/publications

• Contact

– [email protected] – phone: +1-910-695-8884

http://www.scribner.com/fuel-cell-and-electrochemical-hardware/general-electrochemistry-products/150-multichannel-microelectrode-analyzer

http://www.scribner.com/images/mma-citations.pdf

mailto:[email protected]

MMA 900/910 : Configurations, Uses & Example Applications · • Up to 100 working electrodes (WE),...

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