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M.S.ThesisDefense

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Nicole Pacheco

This thesis examines using electrophoretic deposition (EPD) to coat 3D graphite felt with cobalt ferrite nanoparticles. The objectives are to improve the kinetically slow anodic reaction in the solar sulfur-ammonia thermochemical cycle for hydrogen production. Experiments include EPD with different suspensions, adhesion testing of deposits, penetration analysis via SEM, and electrochemical studies. Results show EPD fully penetrates the felt and maximum monolayer coverage is achieved. Deposits on 3 mm felt have the highest current density increase compared to the blank substrate.

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Electrophoretic Deposition of Cobalt Ferrite Nanoparticles into 3D Felt Nicole Shellhammer Pacheco M.S. Thesis Defense Chemical Engineering Committee Members: Professor Jan B. Talbot, Chair Professor Joanna M. McKittrick Professor Justin P. Opatkiewicz 1

2

• Motivation and Objectives • Background • Experiments – Electrophoretic Deposition (EPD) – Adhesion Tests – EPD Penetration – Electrochemical Study • Results & Discussion • Conclusions Outline Image Source: http://www.aliexpress.com/item/Graphite-felt-custom-made-for-vacuum- furnace-Insulation-protection/32398127261.html 2

3

Hydrogen as a fuel • Uses of hydrogen – Burning hydrogen – Hydrogen fuel cells • Advantages of hydrogen as a fuel – Safe – Environmentally-friendly – Can replace fossil fuels used in transportation systems • Challenge: 86 % of hydrogen is produced from burning fossil fuels1 Motivation and Objectives 1Steinfeld, A. International Journal of Hydrogen Energy 2002, 27, 611–619. Image source: http://www.zmescience.com/science/hydrogen-car-fuel-04042013/ 3

4

Objective • Produce hydrogen from clean and sustainable method – Solar sulfur-ammonia (SA) thermochemical cycle Goals • Penetrate and coat nanoparticles into 3D felt with EPD • Improve kinetically slow anodic reaction for SA cycle with EPD deposits of electrocatalysts – Determine EPD conditions and suspension properties Motivation and Objectives Image source: http://www.baseofengineering.com/index.php/2015/06/12/engineers-develop- state-by-state-plan-to-convert-us-to-100-clean-renewable-energy-by-2050/ 4

5

Background • Solar sulfur-ammonia (SA) thermochemical cycle – Oxygen producing thermochemical cycle – Hydrogen producing electrochemical cycle Image source: Taylor, R.; Davenport, R.; Talbot, J.; Herz, R.; Luc, W.; Genders, D.; Symons, P.; Brown, L. Energy Procedia 2014, 49, 2047–2058. 5

6

Hydrogen producing electrochemical cycle: • Kinetically slow anodic reaction in electrolytic reactor – Oxidation of ammonium sulfite to ammonium sulfate Background Electrochemistry Tanakit, R.; Luc, W.; Talbot, ECS Transactions, 58 (42) 1-9 (2014). 6

7

• Advantages of EPD: – Simple apparatus – Short deposition time – Allows various substrate shapes Background Electrophoretic Deposition Image source: Siracuse et al. J. Electrochem. Soc., 137 (1990) Hamaker equation: m Et Electrophoretic mobility: 7 • Bath properties: • Dielectric constant of liquid ( ), and viscosity of liquid ( ) • Surface charge of the particle: zeta potential ( ) measured • C is concentration and A is area of EPD deposit

8

• Filling pores – Silica nanoparticles into porous anodic aluminum oxide film • Penetrate and coat 3D material – EPD deposited nickel oxide film into 3D porous nickel foam Background EPD of 3D Substrates Fori, B.; Taberna, P.; Arurault, L.; Bonino, J. Journal of Colloid and Interface Science 2014, 413, 31–36. Gonzalez, Z.; Ferrari, B.; Sanchez-Herencia, A.; Caballero, A.; Morales, J.; Hernan, L. In Electrophoretic Deposition: Fundamentals and Applications V, Oct. 2015. 8

9

• Penetration equation: – EPD of 10 nm ceramic dielectric particles between carbon nanotubes on stainless steel electrode (50 nm diameter, 20 µm length) – Ratio of Peclet number to Damköhler number (electrophoretic velocity (v) to local deposition rate (k)) Background Penetration by EPD >1000 Bakhoum, E.; Cheng, M. Journal of Applied Physics 2009, 105, 1–6. 9 a = average pore radius, D = diffusion coefficient, gamma = experimental coefficient

10

Objective: Penetrate and coat 3D felt and enhance anodic reaction rate for hydrogen subcycle for SA thermochemical cycle – Electrophoretic Deposition (EPD) – Adhesion Tests – EPD Penetration – Electrochemical Study Experiments 10

11

• Baths: 2 g/L cobalt ferrite nanoparticles in – 100 % ethanol (E) – 100 % acetylacetone with 0.2 wt. % polyethylenimine (AA-PEI) – 90/10 % water/isopropanol (IPA) with 0.05 mM or 1 mM CTAB (hexadecyltrimethlyammonium bromide) Experiments Electrophoretic Deposition (EPD) 11 Desired: Positive zeta potential > 25 mV Image: Zi et al., Journal of Magnetism and Magnetic Materials, 321(2009)1251–1255

12

• Substrates: – 3.14 cm2 of aluminum foil and graphite paper – 1 cm2 of 3 mm carbon, 6 mm graphite felt • E bath EPD conditions: – 20 V - 63 V for 1 or 2 min • AA-PEI bath EPD conditions: – 60 V - 128 V for 1-13 min Experiments Electrophoretic Deposition (EPD) 12

13

• Dry adhesion – Important for removing and drying deposit from bath – Tape test: place on film and remove scotch tape • Wet adhesion – Important for electrochemical tests of deposits – Soak test: 24 hour soak of deposits in de-ionized water Experiments Adhesion Tests 13 Adhesion of EPD deposits from ethanol bath on aluminum foil (weight of sample before & after test)

14

• Penetration calculation into porous carbon – Ratio values based on EPD conditions and suspension properties – Ratio > 1000 means deep penetration can occur into felt • Phillips XL30 ESEM scanning electron microscope (SEM) imaging of EPD deposits (Neil Verma) – Image analysis of top and middle of the 3D felt deposits Experiments EPD Penetration Image source: http://sirius.mtm.kuleuven.be/Research/Equipment/fiches/xl30-esem-feg.html 14

15

• Linear sweep voltammetry of EPD deposits – Oxidation of 2 M ammonium sulfite to ammonium sulfate – Deposits soaked in 2 M ammonium sulfite before (24 or 72 hr) – Princeton Applied Research VersaSTAT 3 potentiostat • Scanned from 0.0 to 1.0 V vs. standard calomel electrode (SCE) • Sweep rate of 50 mV/s • Standard three-compartment electrode cell Experiments Electrochemical Study 15 Image source: http://electronicstructure.wikidot.com/oxygen-reduction-reaction- on-platinum-using-dft 8 cm2 graphite cloth 1 cm2 deposit on 3 mm or 6 mm felt Standard calomel electrode (SCE)

16

• Calculation of monolayer deposit density: 10.2 μg/cm2 – Assume hexagonal close packing (91 % area filled) – 20 nm cobalt ferrite particles into 4.91 cm2 area • EPD from ethanol bath: 5 V for 55 s on aluminum foil Results Electrophoretic Deposition (EPD) 0 2.5 5 7.5 10 12.5 15 0 10 20 30 40 50 60 DepositDensity(µg/cm2) Time (s) 1 monolayer 16 500 nm

17

• Dry adhesion test (Tape test) – 0 to 25 % of the particles were removed – Error: ± 0.01 mg • Wet adhesion test (24 hour soak test) – No particles were removed Results Adhesion Tests 17

18

• EPD on graphite paper (GP) follows Hamaker equation • 3 mm and 6 mm felt may have adsorption of nanoparticles with no electric field (not verified experimentally) • Deposit density greater for 6mm > 3mm > GP Results EPD from Ethanol bath 0.00 0.20 0.40 0.60 0.80 1.00 1.20 1.40 0 10 20 30 40 50 60 70 DepsoitDensity(mg/cm2) Voltage*Time (V*min) GP 3 mm felt 6 mm felt Slope ratios: 3 mm to GP: 1.3 6 mm to GP: 1.7 6 mm to 3 mm: 1.4 18

19

EPD follows Hamaker equation Deposit density greater for Al, GP > 6mm > 3mm Results EPD from AA-PEI bath Slope ratios: Al to 3 mm: 5.6 GP to 3 mm: 5.6 Al to 6 mm: 2.2 GP to 6 mm: 2.2 6 mm to 3 mm: 2.6 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 0 500 1000 1500 2000 Depsoitdensity(mg/cm2) Voltage*Time (V*min) Al GP 3 mm felt 6 mm felt 19

20

• Electrophoretic velocity to local deposition rate into 6 mm felt: – EPD conditions: E, 40 V, 1 min (41 mA, 1.17 mg) – EPD conditions: AA-PEI, 127 V, 4 min (6 mA, 0.79 mg) Results EPD Penetration 20Bakhoum, E.; Cheng, M. Journal of Applied Physics 2009, 105, 1–6. = 8 x 104 >1000 Deep penetration of 3D felt up to 6 mm thick should occur = 5 x 106 >1000 >1000

21

Blanks 3 mm carbon felt 6 mm graphite felt Results EPD Penetration 21

22

3 mm carbon felt EPD deposit conditions: E, 40 V, 1 min, (42 mA, 0.68 mg) Top of the deposit Middle of the deposit Results EPD Penetration 22

23

6 mm graphite felt EPD deposit conditions: E, 40 V, 1 min (41 mA, 1.17 mg) Top of the deposit Middle of the deposit Results EPD Penetration 23

24

• Deposit weight and number of monolayers – E and AA-PEI bath • Maximum monolayers: 27 on graphite paper, 1 on 3 mm felt • Maximum surface coverage of 6 mm felt: ~31 % Results Comparison of EPD baths 24

25

• Linear sweep voltammetry (LSV) from 0 to 1.0 V vs. SCE with scan rate of 50 mV/s in 2 M ammonium sulfite – As reaction increases, i proportional exp(V) – Deposit from ethanol bath into 6 mm graphite felt – EPD conditions: 40 V, 1 min, (41 mA, 1.17 mg) Results Electrochemical Study 25 i iblank

26

• Extrapolated current density of platinum electrode at 0.8 V vs. NHE for 50 mV/s in 2 M ammonium sulfite solution1 imax = 190 mA/cm2 Results Electrochemical Study 261Skavas, E.; Hemmingsen, T. Electrochimica Acta 2007, 52, 3510–3517. • EPD conditions into 6 mm felt with highest electrochemical activity • AA-PEI bath: 127 V for 4 min • E bath: 40 V for 1 min

27

EPD Deposits from Ethanol bath • Ratio current density of deposit compared to blank substrate vs. deposit density – i/iblank for graphite paper and 6 mm felt is ~1.6 – i/iblank for 3 mm felt ranges between 4-8 Results Electrochemical 0 1 2 3 4 5 6 7 8 9 0.00 0.20 0.40 0.60 0.80 1.00 1.20 1.40 i/iblank Deposit Density (mg/cm2) GP 3 mm felt 6 mm felt 27

28

EPD deposits from AA-PEI bath • Ratio current density of deposit compared to blank substrate vs. deposit density – i/iblank for aluminum foil, graphite paper and 6 mm felt is ~1.9 – i/iblank for 3 mm felt ranges between 9-14 Results Electrochemical 28 0 2 4 6 8 10 12 14 16 0.0 1.0 2.0 3.0 4.0 5.0 i/iblank Deposit density (mg/cm2) Al GP 3 mm felt 6 mm felt

29

• Full penetration and coating of 3 mm and 6 mm felt • Maximum number of monolayers deposited – Graphite paper: 27 – 3 mm carbon felt: 1 – 6 mm graphite felt: < 1 • Current density of EPD deposit into 6 mm felt compared to platinum electrode – 32 % imax from AA-PEI bath (127 V for 4 min) – 20 % imax from ethanol bath (40 V for 1 min) • Ratio of current density of deposit to blank substrate – Highest magnitude for 3 mm carbon felt Conclusions 29

30

• Wet adhesion on graphite paper, 3 mm, and 6 mm felt • Determine EPD conditions for 1 monolayer of particles into 6 mm graphite felt • Determine how number of monolayers affect electrochemical activity of EPD deposits (Neil Verma M.S. thesis) Future work 30

31

• Professor Jan B. Talbot (UCSD) • Neil Verma for SEM image analysis (UCSD) • Dr. Richard Herz (UCSD) • Dr. Dave Genders and Dr. Peter Symons (Electrosynthesis Inc.) • Dr. Lloyd Brown (Thermochemical Solutions LLC.) • Roger Davenport and Robin Taylor (Leidos) This work was funded by the Department of Energy, Grant DE-FG36-07GO17002. Acknowledgements 31

32

Thank you! Committee Members: Professor Jan B. Talbot, Chair Professor Joanna M. McKittrick Professor Justin P. Opatkiewicz 32

More Related Content

M.S.ThesisDefense

  • 1. Electrophoretic Deposition of Cobalt Ferrite Nanoparticles into 3D Felt Nicole Shellhammer Pacheco M.S. Thesis Defense Chemical Engineering Committee Members: Professor Jan B. Talbot, Chair Professor Joanna M. McKittrick Professor Justin P. Opatkiewicz 1
  • 2. • Motivation and Objectives • Background • Experiments – Electrophoretic Deposition (EPD) – Adhesion Tests – EPD Penetration – Electrochemical Study • Results & Discussion • Conclusions Outline Image Source: http://www.aliexpress.com/item/Graphite-felt-custom-made-for-vacuum- furnace-Insulation-protection/32398127261.html 2
  • 3. Hydrogen as a fuel • Uses of hydrogen – Burning hydrogen – Hydrogen fuel cells • Advantages of hydrogen as a fuel – Safe – Environmentally-friendly – Can replace fossil fuels used in transportation systems • Challenge: 86 % of hydrogen is produced from burning fossil fuels1 Motivation and Objectives 1Steinfeld, A. International Journal of Hydrogen Energy 2002, 27, 611–619. Image source: http://www.zmescience.com/science/hydrogen-car-fuel-04042013/ 3
  • 4. Objective • Produce hydrogen from clean and sustainable method – Solar sulfur-ammonia (SA) thermochemical cycle Goals • Penetrate and coat nanoparticles into 3D felt with EPD • Improve kinetically slow anodic reaction for SA cycle with EPD deposits of electrocatalysts – Determine EPD conditions and suspension properties Motivation and Objectives Image source: http://www.baseofengineering.com/index.php/2015/06/12/engineers-develop- state-by-state-plan-to-convert-us-to-100-clean-renewable-energy-by-2050/ 4
  • 5. Background • Solar sulfur-ammonia (SA) thermochemical cycle – Oxygen producing thermochemical cycle – Hydrogen producing electrochemical cycle Image source: Taylor, R.; Davenport, R.; Talbot, J.; Herz, R.; Luc, W.; Genders, D.; Symons, P.; Brown, L. Energy Procedia 2014, 49, 2047–2058. 5
  • 6. Hydrogen producing electrochemical cycle: • Kinetically slow anodic reaction in electrolytic reactor – Oxidation of ammonium sulfite to ammonium sulfate Background Electrochemistry Tanakit, R.; Luc, W.; Talbot, ECS Transactions, 58 (42) 1-9 (2014). 6
  • 7. • Advantages of EPD: – Simple apparatus – Short deposition time – Allows various substrate shapes Background Electrophoretic Deposition Image source: Siracuse et al. J. Electrochem. Soc., 137 (1990) Hamaker equation: m Et Electrophoretic mobility: 7 • Bath properties: • Dielectric constant of liquid ( ), and viscosity of liquid ( ) • Surface charge of the particle: zeta potential ( ) measured • C is concentration and A is area of EPD deposit
  • 8. • Filling pores – Silica nanoparticles into porous anodic aluminum oxide film • Penetrate and coat 3D material – EPD deposited nickel oxide film into 3D porous nickel foam Background EPD of 3D Substrates Fori, B.; Taberna, P.; Arurault, L.; Bonino, J. Journal of Colloid and Interface Science 2014, 413, 31–36. Gonzalez, Z.; Ferrari, B.; Sanchez-Herencia, A.; Caballero, A.; Morales, J.; Hernan, L. In Electrophoretic Deposition: Fundamentals and Applications V, Oct. 2015. 8
  • 9. • Penetration equation: – EPD of 10 nm ceramic dielectric particles between carbon nanotubes on stainless steel electrode (50 nm diameter, 20 µm length) – Ratio of Peclet number to Damköhler number (electrophoretic velocity (v) to local deposition rate (k)) Background Penetration by EPD >1000 Bakhoum, E.; Cheng, M. Journal of Applied Physics 2009, 105, 1–6. 9 a = average pore radius, D = diffusion coefficient, gamma = experimental coefficient
  • 10. Objective: Penetrate and coat 3D felt and enhance anodic reaction rate for hydrogen subcycle for SA thermochemical cycle – Electrophoretic Deposition (EPD) – Adhesion Tests – EPD Penetration – Electrochemical Study Experiments 10
  • 11. • Baths: 2 g/L cobalt ferrite nanoparticles in – 100 % ethanol (E) – 100 % acetylacetone with 0.2 wt. % polyethylenimine (AA-PEI) – 90/10 % water/isopropanol (IPA) with 0.05 mM or 1 mM CTAB (hexadecyltrimethlyammonium bromide) Experiments Electrophoretic Deposition (EPD) 11 Desired: Positive zeta potential > 25 mV Image: Zi et al., Journal of Magnetism and Magnetic Materials, 321(2009)1251–1255
  • 12. • Substrates: – 3.14 cm2 of aluminum foil and graphite paper – 1 cm2 of 3 mm carbon, 6 mm graphite felt • E bath EPD conditions: – 20 V - 63 V for 1 or 2 min • AA-PEI bath EPD conditions: – 60 V - 128 V for 1-13 min Experiments Electrophoretic Deposition (EPD) 12
  • 13. • Dry adhesion – Important for removing and drying deposit from bath – Tape test: place on film and remove scotch tape • Wet adhesion – Important for electrochemical tests of deposits – Soak test: 24 hour soak of deposits in de-ionized water Experiments Adhesion Tests 13 Adhesion of EPD deposits from ethanol bath on aluminum foil (weight of sample before & after test)
  • 14. • Penetration calculation into porous carbon – Ratio values based on EPD conditions and suspension properties – Ratio > 1000 means deep penetration can occur into felt • Phillips XL30 ESEM scanning electron microscope (SEM) imaging of EPD deposits (Neil Verma) – Image analysis of top and middle of the 3D felt deposits Experiments EPD Penetration Image source: http://sirius.mtm.kuleuven.be/Research/Equipment/fiches/xl30-esem-feg.html 14
  • 15. • Linear sweep voltammetry of EPD deposits – Oxidation of 2 M ammonium sulfite to ammonium sulfate – Deposits soaked in 2 M ammonium sulfite before (24 or 72 hr) – Princeton Applied Research VersaSTAT 3 potentiostat • Scanned from 0.0 to 1.0 V vs. standard calomel electrode (SCE) • Sweep rate of 50 mV/s • Standard three-compartment electrode cell Experiments Electrochemical Study 15 Image source: http://electronicstructure.wikidot.com/oxygen-reduction-reaction- on-platinum-using-dft 8 cm2 graphite cloth 1 cm2 deposit on 3 mm or 6 mm felt Standard calomel electrode (SCE)
  • 16. • Calculation of monolayer deposit density: 10.2 μg/cm2 – Assume hexagonal close packing (91 % area filled) – 20 nm cobalt ferrite particles into 4.91 cm2 area • EPD from ethanol bath: 5 V for 55 s on aluminum foil Results Electrophoretic Deposition (EPD) 0 2.5 5 7.5 10 12.5 15 0 10 20 30 40 50 60 DepositDensity(µg/cm2) Time (s) 1 monolayer 16 500 nm
  • 17. • Dry adhesion test (Tape test) – 0 to 25 % of the particles were removed – Error: ± 0.01 mg • Wet adhesion test (24 hour soak test) – No particles were removed Results Adhesion Tests 17
  • 18. • EPD on graphite paper (GP) follows Hamaker equation • 3 mm and 6 mm felt may have adsorption of nanoparticles with no electric field (not verified experimentally) • Deposit density greater for 6mm > 3mm > GP Results EPD from Ethanol bath 0.00 0.20 0.40 0.60 0.80 1.00 1.20 1.40 0 10 20 30 40 50 60 70 DepsoitDensity(mg/cm2) Voltage*Time (V*min) GP 3 mm felt 6 mm felt Slope ratios: 3 mm to GP: 1.3 6 mm to GP: 1.7 6 mm to 3 mm: 1.4 18
  • 19. EPD follows Hamaker equation Deposit density greater for Al, GP > 6mm > 3mm Results EPD from AA-PEI bath Slope ratios: Al to 3 mm: 5.6 GP to 3 mm: 5.6 Al to 6 mm: 2.2 GP to 6 mm: 2.2 6 mm to 3 mm: 2.6 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 0 500 1000 1500 2000 Depsoitdensity(mg/cm2) Voltage*Time (V*min) Al GP 3 mm felt 6 mm felt 19
  • 20. • Electrophoretic velocity to local deposition rate into 6 mm felt: – EPD conditions: E, 40 V, 1 min (41 mA, 1.17 mg) – EPD conditions: AA-PEI, 127 V, 4 min (6 mA, 0.79 mg) Results EPD Penetration 20Bakhoum, E.; Cheng, M. Journal of Applied Physics 2009, 105, 1–6. = 8 x 104 >1000 Deep penetration of 3D felt up to 6 mm thick should occur = 5 x 106 >1000 >1000
  • 21. Blanks 3 mm carbon felt 6 mm graphite felt Results EPD Penetration 21
  • 22. 3 mm carbon felt EPD deposit conditions: E, 40 V, 1 min, (42 mA, 0.68 mg) Top of the deposit Middle of the deposit Results EPD Penetration 22
  • 23. 6 mm graphite felt EPD deposit conditions: E, 40 V, 1 min (41 mA, 1.17 mg) Top of the deposit Middle of the deposit Results EPD Penetration 23
  • 24. • Deposit weight and number of monolayers – E and AA-PEI bath • Maximum monolayers: 27 on graphite paper, 1 on 3 mm felt • Maximum surface coverage of 6 mm felt: ~31 % Results Comparison of EPD baths 24
  • 25. • Linear sweep voltammetry (LSV) from 0 to 1.0 V vs. SCE with scan rate of 50 mV/s in 2 M ammonium sulfite – As reaction increases, i proportional exp(V) – Deposit from ethanol bath into 6 mm graphite felt – EPD conditions: 40 V, 1 min, (41 mA, 1.17 mg) Results Electrochemical Study 25 i iblank
  • 26. • Extrapolated current density of platinum electrode at 0.8 V vs. NHE for 50 mV/s in 2 M ammonium sulfite solution1 imax = 190 mA/cm2 Results Electrochemical Study 261Skavas, E.; Hemmingsen, T. Electrochimica Acta 2007, 52, 3510–3517. • EPD conditions into 6 mm felt with highest electrochemical activity • AA-PEI bath: 127 V for 4 min • E bath: 40 V for 1 min
  • 27. EPD Deposits from Ethanol bath • Ratio current density of deposit compared to blank substrate vs. deposit density – i/iblank for graphite paper and 6 mm felt is ~1.6 – i/iblank for 3 mm felt ranges between 4-8 Results Electrochemical 0 1 2 3 4 5 6 7 8 9 0.00 0.20 0.40 0.60 0.80 1.00 1.20 1.40 i/iblank Deposit Density (mg/cm2) GP 3 mm felt 6 mm felt 27
  • 28. EPD deposits from AA-PEI bath • Ratio current density of deposit compared to blank substrate vs. deposit density – i/iblank for aluminum foil, graphite paper and 6 mm felt is ~1.9 – i/iblank for 3 mm felt ranges between 9-14 Results Electrochemical 28 0 2 4 6 8 10 12 14 16 0.0 1.0 2.0 3.0 4.0 5.0 i/iblank Deposit density (mg/cm2) Al GP 3 mm felt 6 mm felt
  • 29. • Full penetration and coating of 3 mm and 6 mm felt • Maximum number of monolayers deposited – Graphite paper: 27 – 3 mm carbon felt: 1 – 6 mm graphite felt: < 1 • Current density of EPD deposit into 6 mm felt compared to platinum electrode – 32 % imax from AA-PEI bath (127 V for 4 min) – 20 % imax from ethanol bath (40 V for 1 min) • Ratio of current density of deposit to blank substrate – Highest magnitude for 3 mm carbon felt Conclusions 29
  • 30. • Wet adhesion on graphite paper, 3 mm, and 6 mm felt • Determine EPD conditions for 1 monolayer of particles into 6 mm graphite felt • Determine how number of monolayers affect electrochemical activity of EPD deposits (Neil Verma M.S. thesis) Future work 30
  • 31. • Professor Jan B. Talbot (UCSD) • Neil Verma for SEM image analysis (UCSD) • Dr. Richard Herz (UCSD) • Dr. Dave Genders and Dr. Peter Symons (Electrosynthesis Inc.) • Dr. Lloyd Brown (Thermochemical Solutions LLC.) • Roger Davenport and Robin Taylor (Leidos) This work was funded by the Department of Energy, Grant DE-FG36-07GO17002. Acknowledgements 31
  • 32. Thank you! Committee Members: Professor Jan B. Talbot, Chair Professor Joanna M. McKittrick Professor Justin P. Opatkiewicz 32

Editor's Notes

  1. EPD is a method that deposits suspended particles in a liquid medium under an applied electric field into a substrate Zeta potential measures the potential difference of the diffusion layer, which is between the shear plane and the surrounding liquid Vacuum permittivity constant
  2. Peclet # study of transport through a medium expressed as the rate of advection by the rate of diffusion The Damköhler number is defined as the reaction rate by the diffusive mass transfer rate a is average pore radius, D is diffusion coefficient
  3. Slope ratio: rate of deposition
  4. Driving force (voltage), rate of reaction I proportional exp(V)