A photolithographic process for investigation of electrode reaction sites in solid oxide fuel cells

Koep, Erik; Compson, Charles; Liu, Meilin; Zhou, Zhiping

doi:10.1016/j.ssi.2004.07.012

Cited by 34 publications

(32 citation statements)

References 24 publications

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“…Thus the DL has many grain boundaries, which can modify the transport and catalyic properties compared to conventional SOFC materials with grains ranging typically between 100 nm and 1 μm. In recent years, ceramic nanomaterials and thin films have been drawing ever-growing interest [17], notably in fields such as of grain growth [18], electrical conductivity [19] micro-SOFC [20,21] and geometrically well-defined electrodes [4][5][6]. Further work is still needed to clarify the effect of nanoscaled grain size on catalytic and transport properties of SOFC materials.…”

Section: Discussionmentioning

confidence: 99%

“…The latter were obtained from a model interface that consisted of a polished gadolinium-doped ceria (CGO) on top of which a thin dense LSCF layer with well-controlled dimensions was prepared by pulsed lased deposition (PLD) and subsequently structured with photolithography. Geometrically well-defined electrodes that allow for the control of key parameters, such as the length of triple phase boundary (tpb) gas/electrode/ electrolyte and the bulk diffusion length, become increasingly popular for experimental investigations of reaction mechanisms [2][3][4][5][6] in the field of SOFC. In this study the variation of the film thickness has been used to probe the influence of oxygen bulk diffusion on the overall reaction kinetics.…”

Section: Introductionmentioning

confidence: 99%

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Oxygen reduction at thin dense La0.52Sr0.48Co0.18Fe0.82O3–δ electrodes

et al. 2007

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The mechanism and kinetics of oxygen reduction at thin dense two-dimensional La 0:52 Sr 0:48 Co 0:18 Fe 0:82 O 3Àd (LSCF) electrodes have been investigated in air between 500 and 700°C with electrochemical impedance spectroscopy and steady-state voltammetry. Dense and geometrically well-defined LSCF films with various thicknesses ranging between 16 and 766 nm have been prepared on cerium gadolinium oxide substrates by pulsed laser deposition and structured with photolithography. The current collection was ensured by a porous LSCF layer. A good agreement was found between the experimental data and the impedance of the reaction model calculated with statespace modelling for various electrode potentials and thicknesses. It was evidenced that oxygen adsorption, incorporation into the LSCF and bulk diffusion are ratedetermining while charge transfer at the electrode/electrolyte interface remains at quasi-equilibrium. The 16 and 60 nm thin dense LSCF electrodes appear to be more active towards oxygen reduction than thicker layers and porous films at 600 and 700°C.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Oxygen reduction at thin dense La0.52Sr0.48Co0.18Fe0.82O3–δ electrodes

et al. 2007

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“…Unlike porous electrodes in conventional SOFC designs, such microelectrodes enable systematic investigations of electrochemical processes at the TPB, as demonstrated for a number of materials systems [21][22][23][24][25][26]. In this study, platinum was used as a model system because it is a classic, well-studied electrode with simple chemistry and low oxygen diffusivity such that oxygen incorporation is confined to the TPB at the electrode perimeter [10,25,[27][28][29][30].…”

Section: Introductionmentioning

confidence: 99%

Highly enhanced electrochemical performance of silicon-free platinum–yttria stabilized zirconia interfaces

2008

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In the drive to achieve economically viable solid oxide fuel cells, efforts have been directed towards substantially decreasing their operating temperature. Unfortunately, these efforts have been hindered by extremely sluggish electrode kinetics at reduced temperatures. In this report, we show that silicon impurities on the surface of the electrolyte play a critical role in influencing electrode kinetics. More specifically, improvements by as much as three orders of magnitude are reported for the performance of platinum electrodes on yttria-stabilized zirconia electrolytes prepared as high purity thin films with a largely Sifree surface. These improvements in performance are estimated to enable operation of a solid oxide fuel cell down to approximately 400°C.

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“…[8][9][10][11] Therefore, numerous studies have employed porous, high-surface-area electrodes with nanometer-scale LSM particle sizes [12][13][14] or composite LSM-YSZ 3,15,16 to enhance overall TPB length and thus lower ORR resistance and overpotential. However, it is not apparent how LSM particle sizes alter the rate-limiting reaction of ORR and the contributions of the TPB and bulk pathway 6,17,18 as a function of temperature, which limits the efficiency optimization of porous electrodes for intermediate temperature operation.Electrodes with well-defined geometries, such as dense coneshaped pellets, 19-21 thin films, 22-25 and patterned microelectrodes, [26][27][28][29][30][31][32][33] have been used to provide simple scaling relationships between ORR impedance and electrode dimensions, such as TPB length. Mizusaki et al 6 first demonstrated that oxygen-ion diffusion can occur through dense, oxygen-over-stoichiometric LSM electrodes having thickness of 1-2 m at 700-900°C.…”

mentioning

confidence: 99%

“…Electrodes with well-defined geometries, such as dense coneshaped pellets, [19][20][21] thin films, [22][23][24][25] and patterned microelectrodes, [26][27][28][29][30][31][32][33] have been used to provide simple scaling relationships between ORR impedance and electrode dimensions, such as TPB length. Mizusaki et al 6 first demonstrated that oxygen-ion diffusion can occur through dense, oxygen-over-stoichiometric LSM electrodes having thickness of 1-2 m at 700-900°C.…”

mentioning

confidence: 99%

Thickness Dependence of Oxygen Reduction Reaction Kinetics on Strontium-Substituted Lanthanum Manganese Perovskite Thin-Film Microelectrodes

O’

Shao‐Horn

2009

Electrochem. Solid-State Lett.

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Oxygen reduction reaction ͑ORR͒ kinetics was investigated on dense La 0.8 Sr 0.2 MnO 3 microelectrodes as a function of temperature and microelectrode thickness using electrochemical impedance spectroscopy. The surface oxygen exchange and mixed bulk/threephase-boundary ͑TPB͒ charge transfer process were found to control ORR kinetics at high and low temperatures, respectively. The transition temperature from the mixed bulk/TPB charge transfer control to surface oxygen exchange was found to be highly dependent on the microelectrode thickness ͑ϳ600°C for 65 nm vs ϳ800°C for 705 nm͒. These findings can be used to guide the design of electrodes that can operate at intermediate temperatures. Solid oxide fuel cells ͑SOFCs͒ that utilize 8 mol % yttriastabilized zirconia ͑YSZ͒ electrolyte, La 1−x Sr x MnO 3 ͑LSM͒ cathode, and nickel-YSZ anode typically operate at temperatures above 800°C. To reduce SOFC cost and increase SOFC durability, intense research efforts have been focused on reducing operating temperatures to 700°C or lower without sacrificing SOFC efficiency. [1][2][3] However, the main barrier to achieve acceptable SOFC efficiency at intermediate temperatures is the voltage loss at the LSM cathode, where oxygen reduction reaction ͑ORR͒ occurs. 4 Because oxygen ion conduction is poor in LSM, [5][6][7] it is generally believed that the vicinity of three-phase boundaries ͑TPBs͒ of LSM cathode constitutes the active site for ORR. [8][9][10][11] Therefore, numerous studies have employed porous, high-surface-area electrodes with nanometer-scale LSM particle sizes [12][13][14] or composite LSM-YSZ 3,15,16 to enhance overall TPB length and thus lower ORR resistance and overpotential. However, it is not apparent how LSM particle sizes alter the rate-limiting reaction of ORR and the contributions of the TPB and bulk pathway 6,17,18 as a function of temperature, which limits the efficiency optimization of porous electrodes for intermediate temperature operation.Electrodes with well-defined geometries, such as dense coneshaped pellets, 19-21 thin films, 22-25 and patterned microelectrodes, [26][27][28][29][30][31][32][33] have been used to provide simple scaling relationships between ORR impedance and electrode dimensions, such as TPB length. Mizusaki et al. 6 first demonstrated that oxygen-ion diffusion can occur through dense, oxygen-over-stoichiometric LSM electrodes having thickness of 1-2 m at 700-900°C. Brichzin et al. 28,29 have subsequently utilized microelectrodes with a thickness of 100 nm to show that ORR occurs predominantly via the bulk pathway instead of the TPB pathway at 800°C. In addition, Koep et al. 30 have used dense, patterned LSM electrodes of different thickness to show a critical thickness of 360 nm at 700°C, where the bulk pathway dominates having surface reactions as rate limiting for ORR. More recently, la O' et al. 33 have employed microelectrodes to propose four distinct processes during ORR on LSM: ͑i͒ ion transport in 8YSZ, ͑ii͒ a surface diffusion process on LSM, ͑iii͒ at least one surface...

show abstract

A photolithographic process for investigation of electrode reaction sites in solid oxide fuel cells

Cited by 34 publications

References 24 publications

Oxygen reduction at thin dense La0.52Sr0.48Co0.18Fe0.82O3–δ electrodes

Oxygen reduction at thin dense La0.52Sr0.48Co0.18Fe0.82O3–δ electrodes

Highly enhanced electrochemical performance of silicon-free platinum–yttria stabilized zirconia interfaces

Thickness Dependence of Oxygen Reduction Reaction Kinetics on Strontium-Substituted Lanthanum Manganese Perovskite Thin-Film Microelectrodes

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