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Atomic Layer Deposition of Zirconium Oxide for Fuel Cell Applications UIC REU – Summer 2011 AMReL Lab, UIC Department of Bioengineering and Department.

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Presentation on theme: "Atomic Layer Deposition of Zirconium Oxide for Fuel Cell Applications UIC REU – Summer 2011 AMReL Lab, UIC Department of Bioengineering and Department."— Presentation transcript:

1 Atomic Layer Deposition of Zirconium Oxide for Fuel Cell Applications UIC REU – Summer 2011 AMReL Lab, UIC Department of Bioengineering and Department of Chemical Engineering Christine James University of Michigan, Department of Chemical Engineering

2 Overview Background Atomic Layer Deposition Data Collected Future Work

3 Fuel Cell Advantages Provides clean energy – Hydrogen fuel cells – only emit water Very efficient – Fuel Values Hydrogen: kJ/g Gasoline: 48 kJ/g Coal: kJ/g Santhanam et al., Introduction to Hydrogen Technology, 2009, Hoboken, NJ: J. Wiley. Fossil fuel 2007 Environmentally friendly Coal 23 % Nuclear Power 8 % Renewable Energy 6 % Petroleum 40 % Natural Gas 23 % Source: US Energy Information Agency

4 Sections of the Fuel Cell Cathode – Oxygen is reduced Anode – Hydrogen is oxidized Electrolyte – Transports the oxygen ions www1.eere.energy.gov SOFC FUEL CELL Fuel InAir In Unused Gases Out Excess Fuel and Water Electrical Current

5 Solid Oxide Fuel Cells (SOFCs) Current SOFCs are high temperature – Temperature: about 1000 °C Intermediate Temperature Fuel Cells – Temperature: °C – Smaller scale applications – Allows use of alternate materials – Starts and stops faster – Reduces corrosion – Offers a wide range of possibilities

6 Problem with Reducing Temperature High temperatures needed to transport O 2- ions – Requirement can be as high as 1200° C – Low temperatures cause ionic resistance Deposit electrolytes and analyze – Samples from atomic to bulk-like thickness – Method to be used: Atomic Layer Deposition Deposit oxide layers on silicon then platinum (Pt) Approach

7 Atomic Layer Deposition (ALD) H2OH2O Tri-methyl aluminum Al(CH 3 ) 3(g) Methyl group (CH 3 ) 3(g) Hydroxyl (OH) from surface absorbed H 2 O Reaction of TMA with OH Methane reaction product CH 4

8 Chosen Precursor Niinistö, et al., Advanced Engineering Materials, 2009, 11, No.4, 223. Precursors Growth Temperature Impurities Metal PrecursorO source Range (°C)Preferred (°C)Saturation verified C [-at%]H [-at%] at 300 °C ZyALDOzone Yes <1N.R.

9 ALD System ZyALD

10 Pulse and Purge times required Reactor Temperature: 300°C Bubbler Temperature: 50°C Bubbler Pressure: 10 torr Precursor: ZyALD Precursor Pulse Time: Precursor Purge Time: Oxidizer Pulse Time: Oxidizer Purge Time: Run for 40 cycles Varied 6 s 20 s Varied1.5 s Varied 10 s 17 s 1 s Varied Zr

11 Temperature Window Reactor Temperature: Varied Bubbler Temperature: 50°C Bubbler Pressure: 10 torr Precursor: ZyALD Precursor CondensationPrecursor Decomposition Temperature Window

12 Comparison to Work from another group Niinistö, et al., J. Mater. Chem. 18, 5243 (2008).

13 Thickness vs. Cycles Run Reactor Temperature: 300°C Bubbler Temperature: 50°C Bubbler Pressure: 10 torr Precursor: ZyALD Slope:.87 R² =

14 Future Work 1.Deposit the zirconium oxide on Platinum 2.Run electrochemical analysis Silicon Substrate Electrolyte: Zirconium Oxide Platinum

15 Summary Goal is to lower operating temperature of the fuel cell – By decreasing electrolyte layer thickness Atomic Layer Deposition (ALD) is being used Have determined some necessary parameters: – Pulse and Purge times – Temperature Window for ALD Have compared cycles and thickness – Proved linear relationship Next Steps: – Deposit on Platinum – Run Electrochemical analysis

16 Acknowledgements National Science Foundation – EEC-NSF Grant # Graduate Mentor: Runshen Xu Professor Takoudis and Professor Jursich


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