MRS Fall 2009: Wednesday afternoon
Afternoon. The next talk features a former co-worker from Andreas Stein's group on the author list. I'm only having a look at a couple before I head to do other work here.
Y7.1 "Designing Electrocatalytic Nanarchitechtures in 3D" Debra Rolison (US NRL)
Here they're using aerogels for their interconnected 3D architectures. These have huge surface-volume ratios (slilca aerogels are ~106 cm–. The bonded nanoparticle network behaves as if there are no grain boundaries, which is handy for electrocatalysis. Have a look at those pictures: they're amazingly light and thermally insulating.
She described three systems:
Co-operative bifunctional neighbours. Au-TiO2 does room temperature catalytic oxidation of CO to CO2. They saw efficient catalysis with 5 nm particles, with 200–300 µmol/s/(g Au). Despite the larger particles, the environment of multiple titania-gold contacts, so there were more three-phase boundaries than catalysts prepared by traditional impregnation techniques.They think that there's a charge transport role from the titania aerogel, hence electrocatalysis.
Wired site vacancies (O2– nanowire). Gold-modified, gadolinium-doped, ceria aerogels for WGS. Here oxygen vacancies are the key, and here's where ceria aerogels come to the forefront. For this, they have to use epoxide-driven sol-gel synthesis. The method allows doping of other materials, here, lanthanides.
So using Gd-doped ceria doped with gold, they seem some WGS activity, but not to the state-of-the-art levels of just under 1 µmol/s/(g Au).
Mimicking Vulcan carbon, especially sulfur-functionalised to hold catalysts. The high-surface area carbon is also interesting for Pd-support, say for hydrogen peroxide in Mg/peroxide fuel cell.
Y7.2 "Synthesis of high surface area materials for solid oxide fuel cells (SOFCs)" Robin Chao (Carnegie Mellon)
Their goal is to improve the cathode (oxygen reduction) reaction. The question is what's the rate-limiting step? Currently cathodes are 4-30 m2/g; they want larger and are looking at evaporation induced self assembly and SBA-15 (and some "hard" templating methods) to make (La,Sr)MnO3 with higher surface areas.
Y7.1 "Designing Electrocatalytic Nanarchitechtures in 3D" Debra Rolison (US NRL)
Here they're using aerogels for their interconnected 3D architectures. These have huge surface-volume ratios (slilca aerogels are ~106 cm–. The bonded nanoparticle network behaves as if there are no grain boundaries, which is handy for electrocatalysis. Have a look at those pictures: they're amazingly light and thermally insulating.
She described three systems:
Co-operative bifunctional neighbours. Au-TiO2 does room temperature catalytic oxidation of CO to CO2. They saw efficient catalysis with 5 nm particles, with 200–300 µmol/s/(g Au). Despite the larger particles, the environment of multiple titania-gold contacts, so there were more three-phase boundaries than catalysts prepared by traditional impregnation techniques.They think that there's a charge transport role from the titania aerogel, hence electrocatalysis.
Wired site vacancies (O2– nanowire). Gold-modified, gadolinium-doped, ceria aerogels for WGS. Here oxygen vacancies are the key, and here's where ceria aerogels come to the forefront. For this, they have to use epoxide-driven sol-gel synthesis. The method allows doping of other materials, here, lanthanides.
So using Gd-doped ceria doped with gold, they seem some WGS activity, but not to the state-of-the-art levels of just under 1 µmol/s/(g Au).
Mimicking Vulcan carbon, especially sulfur-functionalised to hold catalysts. The high-surface area carbon is also interesting for Pd-support, say for hydrogen peroxide in Mg/peroxide fuel cell.
Y7.2 "Synthesis of high surface area materials for solid oxide fuel cells (SOFCs)" Robin Chao (Carnegie Mellon)
Their goal is to improve the cathode (oxygen reduction) reaction. The question is what's the rate-limiting step? Currently cathodes are 4-30 m2/g; they want larger and are looking at evaporation induced self assembly and SBA-15 (and some "hard" templating methods) to make (La,Sr)MnO3 with higher surface areas.
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