Eric M. Stuve Eric M. Stuve Department of Chemical Department of Chemical Engineering Engineering University of Washington University of Washington FY2002 FY2002 6.1 Electrochemistry 6.1 Electrochemistry Review Review March 4-6, 2002 March 4-6, 2002 Annapolis, MD Annapolis, MD Surface Reaction Fundamentals in Direct Oxidation Hydrocarbon Fuel Cells
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Eric M. Stuve Department of Chemical Engineering University of Washington FY2002
Surface Reaction Fundamentals in Direct Oxidation Hydrocarbon Fuel Cells. Eric M. Stuve Department of Chemical Engineering University of Washington FY2002 6.1 Electrochemistry Review March 4-6, 2002 Annapolis, MD. MOTIVATION. APPROACH. - PowerPoint PPT Presentation
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Eric M. StuveEric M. StuveDepartment of Chemical Department of Chemical
Non-Faradaic Electrochemical Modification of Catalytic Activity
WE
O2- O2- O2-
CE
REVW
C
VW
R
I
G-P
YSZ
Vayenas’ experimental setup for NEMCA. WE, RE, and CE are working (Pt), reference (Pt) and counter (Ag) electrodes, respectively; G-P is a galvanostat-potentiostat.[Adapted from Vayenas, 1993]FARADAIC EFFICIENCY, (-3x104 to 3x105)
0r
r=ρ
RATE ENHANCEMENT RATIO, ρ(0 to 150)
( )FI
rr
2/0−=Λ
licElectrophi
bicElectropho
→<→>
11
Reproduced from Vayenas, Ind. Eng. Chem. Res., 2001, 40, 4209-4215.
O2 Spillover?
Sub-surface O2?
Three phase boundary role?
Pt TIP
CxHy
CO2
H2O
O2– O2–O2– O2–O2–SOLID OXIDE
O
OMOxO
O OO
O
O2–O2–
TPB
CATALYST
SIDE VIEW FRONT VIEW
Emitter Tip Studies of Metal / Solid Oxide / Fuel Reactions
PREVIOUS WORK
Water Ion Cluster Formation
Low Temperature (<165 K) Field Desorption from Adsorbed Ice Layers (Amorphous and Crystalline)Field Ion Emission from Field Adsorbed Water Layers (>165 K)Developed 2-Step Ion Dissociation / Emission Mechanism
Water / Methanol Ion Cluster Formation
Field Ion Emission from Field Adsorbed Water/Methanol Mixtures (>165 K)
• Importance of Solvation for Dissociation and Emission
Water / Methanol Ion Cluster Formation• Behavior Similar to Previous Water Results
• Mixed H+(CH3OH)m(H2O)n Clusters Observed
• Presence of MeOH Alters Emission and Solvation
Successful Cerium Deposition on Pt Tip• Field Emission Spectroscopy Shows Deposition
• Work Function of Tip Decreased
Results DoD Payoff
Provide fundamental information about relative tendencies of bond breaking in electrocatalysis, surface reaction intermediates, carbon deposition, and the role of oxygen in direct hydrocarbon oxidation important for an overall understanding of direct oxidation hydrocarbon fuel cells.