title: Making the most of a scarce platinum-group metal: conductive ruthenia nanoskins on insulating silica paper.
abstract: Subambient thermal decomposition of ruthenium tetroxide from nonaqueous solution onto porous SiO(2) substrates creates 2-3 nm thick coatings of RuO(2) that cover the convex silica walls comprising the open, porous structure. The physical properties of the resultant self-wired nanoscale ruthenia significantly differ depending on the nature of the porous support. Previously reported RuO(2)-modified SiO(2) aerogels display electron conductivity of 5 x 10(-4) S cm(-1) (as normalized to the geometric factor of the insulating substrate, not the conducting ruthenia phase), whereas RuO(2)-modified silica filter paper at approximately 5 wt % RuO(2) exhibits approximately 0.5 S cm(-1). Electron conduction through the ruthenia phase as examined from -160 to 260 degrees C requires minimal activation energy, only 8 meV, from 20 to 260 degrees C. The RuO(2)(SiO(2)) fiber membranes are electrically addressable, capable of supporting fast electron-transfer reactions, express an electrochemical surface area of approximately 90 m(2) g(-1) RuO(2), and exhibit energy storage in which 90% of the total electron-proton charge is stored at the outer surface of the ruthenia phase. The electrochemical capacitive response indicates that the nanocrystalline RuO(2) coating can be considered to be a single-unit-thick layer of the conductive oxide, as physically stabilized by the supporting silica fiber.
authors.affiliation: Surface Chemistry Branch, Code 6170, Naval Research Laboratory, Washington, D.C. 20375, USA.
authors.forename: Christopher N
authors.initials: CN
authors.lastname: Chervin
authors.forename: Alia M
authors.initials: AM
authors.lastname: Lubers
authors.forename: Katherine A
authors.initials: KA
authors.lastname: Pettigrew
authors.forename: Jeffrey W
authors.initials: JW
authors.lastname: Long
authors.forename: Mark A
authors.initials: MA
authors.lastname: Westgate
authors.forename: John J
authors.initials: JJ
authors.lastname: Fontanella
authors.forename: Debra R
authors.initials: DR
authors.lastname: Rolison