Preserving Nanomorphology in YSZ Scaffolds at High Temperatures via In Situ Carbon Templating of Hybrid Materials

Cottam, Matthew A.; Muhoza, Sixbert P.; Gross, Michael D.

doi:10.1111/jace.14306

Cited by 8 publications

(19 citation statements)

References 41 publications

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“…Phase purity was confirmed by X-ray diffraction (XRD) as previously reported by Cottam et al 14 The carbon template concentration was quantified using TGA ( Figure 2). The carbon template concentration was 4 wt% and 64 wt% of total solids for glucose:metals molar ratios of 0:1 and 4.5:1.…”

Section: Representative Resultsmentioning

confidence: 86%

High Temperature Fabrication of Nanostructured Yttria-Stabilized-Zirconia (YSZ) Scaffolds by In Situ Carbon Templating Xerogels

Muhoza

Cottam

Gross

2017

JoVE

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We demonstrate a method for the high temperature fabrication of porous, nanostructured yttria-stabilized-zirconia (YSZ, 8 mol% yttria - 92 mol% zirconia) scaffolds with tunable specific surface areas up to 80 m·g. An aqueous solution of a zirconium salt, yttrium salt, and glucose is mixed with propylene oxide (PO) to form a gel. The gel is dried under ambient conditions to form a xerogel. The xerogel is pressed into pellets and then sintered in an argon atmosphere. During sintering, a YSZ ceramic phase forms and the organic components decompose, leaving behind amorphous carbon. The carbon formed in situ serves as a hard template, preserving a high surface area YSZ nanomorphology at sintering temperature. The carbon is subsequently removed by oxidation in air at low temperature, resulting in a porous, nanostructured YSZ scaffold. The concentration of the carbon template and the final scaffold surface area can be systematically tuned by varying the glucose concentration in the gel synthesis. The carbon template concentration was quantified using thermogravimetric analysis (TGA), the surface area and pore size distribution was determined by physical adsorption measurements, and the morphology was characterized using scanning electron microscopy (SEM). Phase purity and crystallite size was determined using X-ray diffraction (XRD). This fabrication approach provides a novel, flexible platform for realizing unprecedented scaffold surface areas and nanomorphologies for ceramic-based electrochemical energy conversion applications, e.g. solid oxide fuel cell (SOFC) electrodes.

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Section: Representative Resultsmentioning

confidence: 86%

High Temperature Fabrication of Nanostructured Yttria-Stabilized-Zirconia (YSZ) Scaffolds by In Situ Carbon Templating Xerogels

Muhoza

Cottam

Gross

2017

JoVE

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“…Material preparation.-NanoYSZ was generated via an in situ carbon templating processing method, which has also been shown to generate ultra-high surface area particles for other SOFC relevant mixed-metal-oxides including GDC, LSCF, and strontium titanate. [17][18][19][20] The in situ carbon templating method involves two steps. First, a hybrid inorganic-organic material containing stoichiometric amounts of metal components of the desired mixed-metaloxide is heat treated at 850 °C-1350 °C in an inert atmosphere such as nitrogen or argon.…”

Section: Methodsmentioning

confidence: 99%

Enhancing Activity, Charge Transport, Power Production, and Stability of Commercial Solid Oxide Fuel Cells with Yttria-Stabilized Zirconia Nanoparticles

Muhoza¹,

Lee²,

Song³

et al. 2020

J. Electrochem. Soc.

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Interconnected networks of 10-30 nm yttria-stabilized zirconia (YSZ) nanoparticles dramatically enhance both the electrocatalytic activity and bulk charge transport of commercial lanthanum strontium manganite (LSM)-YSZ solid oxide fuel cell (SOFC) cathodes. The improvement in both electrode functions increases the maximum power density of the commercial SOFC by 90%. In comparison, modifying cathodes with lanthanum strontium cobalt ferrite (LSCF) and praseodymium barium cobaltite (PBC) nanoparticles, highly active catalysts with mixed ionic-electronic conductivity (MIEC), only enhances electrocatalytic activity. The combination of dual enhanced electrode functions with nanoYSZ results in a maximum power density that is 50% and 11% higher than LSCF and PBC, respectively. Finally, the performance stability over time is highest for nanoYSZ modified cells.

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“…PO hybrid materials of YSZ (YSZ-PO) were synthesized with ZrCl 4 (99.5+%, Alfa Aesar), Y(NO 3 ) 3 • 6H 2 O (99.9%, Alfa Aesar), glucose (≥ 99.9%, Alfa Aesar), and PO (≥ 99.5%, Sigma-Aldrich) as described in detail elsewhere. [41][42][43] The salts were dissolved in deionized water in a Zr:Y:H 2 O molar ratio of 5.75:1:650 with magnetic stirring. Glucose was then dissolved in the solution and PO was subsequently added to the solution.…”

Section: Methodsmentioning

confidence: 99%

“…All hybrid material formulations were sintered at 1050 • C, but PO hybrid materials with a 5:1 Glucose:M molar ratio and CA hybrid materials with a 10:10:1 CA:EG:M molar ratio were also sintered at 1150 • C, 1250 • C, and 1350 • C. In addition, YSZ-PO with a 5:1 Glucose:M molar ratio was sintered at 850 • C and 950 • C. In all cases, the sintered samples were black indicating that amorphous carbon had formed in situ. 41 Upon calcination in air at 700 • C, the samples were white for YSZ and STO, yellow for GDC, and black for LSCF.…”

Section: Methodsmentioning

confidence: 99%

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High Surface Area SOFC Electrode Materials Prepared at Traditional Sintering Temperatures

Muhoza

Barrett

Cottam

et al. 2018

J. Electrochem. Soc.

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Solid oxide fuel cell (SOFC) electrode materials with surface areas up to 99 m 2 • g −1 were prepared at traditional sintering temperatures, 1050 • C-1350 • C, by sintering hybrid inorganic-organic materials in an inert atmosphere followed by calcination in air at 700 • C. The electrode materials investigated were yttria-stabilized zirconia (YSZ), lanthanum strontium cobalt ferrite (LSCF), gadolinia doped ceria (GDC), and strontium titanate (STO). During sintering, an amorphous carbon template forms in situ and remains throughout the sintering process, aiding in the creation and preservation of mixed-metal-oxide nanomorphology. The carbon template is removed during subsequent calcination in air at 700 • C, leaving behind a nanostructured ceramic. Phase stability, carbon template concentration, and specific surface area was determined for each mixed-metal-oxide. Final specific surface areas up to 83, 66, 95, and 99 m 2 • g −1 were achieved for YSZ, LSCF, GDC, and STO, respectively. The impact of high surface area YSZ on symmetrical YSZ-lanthanum strontium ferrite (LSF) cathode cell performance was evaluated in the temperature range of 550 • C-800 • C. Adding nanostructured YSZ decreased the electrochemical impedance by 45% at 550 • C. The performance improvement lessened with increasing temperature, and at 800 • C there was essentially no improvement. The findings reveal a promising approach to improving low temperature SOFC performance.

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Preserving Nanomorphology in YSZ Scaffolds at High Temperatures via In Situ Carbon Templating of Hybrid Materials

Cited by 8 publications

References 41 publications

High Temperature Fabrication of Nanostructured Yttria-Stabilized-Zirconia (YSZ) Scaffolds by <em>In Situ</em> Carbon Templating Xerogels

High Temperature Fabrication of Nanostructured Yttria-Stabilized-Zirconia (YSZ) Scaffolds by <em>In Situ</em> Carbon Templating Xerogels

Enhancing Activity, Charge Transport, Power Production, and Stability of Commercial Solid Oxide Fuel Cells with Yttria-Stabilized Zirconia Nanoparticles

High Surface Area SOFC Electrode Materials Prepared at Traditional Sintering Temperatures

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