10.1021/nl900528q.s001 Christopher N. Chervin Christopher N. Chervin Alia M. Lubers Alia M. Lubers Katherine A. Pettigrew Katherine A. Pettigrew Jeffrey W. Long Jeffrey W. Long Mark A. Westgate Mark A. Westgate John J. Fontanella John J. Fontanella Debra R. Rolison Debra R. Rolison Making the Most of a Scarce Platinum-Group Metal: Conductive Ruthenia Nanoskins on Insulating Silica Paper American Chemical Society 2009 Conductive Ruthenia Nanoskins Insulating Silica PaperSubambient SiO 2 substrates electrochemical surface area ruthenia phase nanocrystalline RuO 2 coating exhibit energy storage electrochemical capacitive response 2009-06-10 00:00:00 Journal contribution https://acs.figshare.com/articles/journal_contribution/Making_the_Most_of_a_Scarce_Platinum_Group_Metal_Conductive_Ruthenia_Nanoskins_on_Insulating_Silica_Paper/2851120 Subambient thermal decomposition of ruthenium tetroxide from nonaqueous solution onto porous SiO<sub>2</sub> substrates creates 2−3 nm thick coatings of RuO<sub>2</sub> 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<sub>2</sub>-modified SiO<sub>2</sub> aerogels display electron conductivity of 5 × 10<sup>−4</sup> S cm<sup>−1</sup> (as normalized to the geometric factor of the insulating substrate, not the conducting ruthenia phase), whereas RuO<sub>2</sub>-modified silica filter paper at ∼5 wt % RuO<sub>2</sub> exhibits ∼0.5 S cm<sup>−1</sup>. Electron conduction through the ruthenia phase as examined from −160 to 260 °C requires minimal activation energy, only 8 meV, from 20 to 260 °C. The RuO<sub>2</sub>(SiO<sub>2</sub>) fiber membranes are electrically addressable, capable of supporting fast electron-transfer reactions, express an electrochemical surface area of ∼90 m<sup>2</sup> g<sup>−1</sup> RuO<sub>2</sub>, 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<sub>2</sub> coating can be considered to be a single-unit-thick layer of the conductive oxide, as physically stabilized by the supporting silica fiber.