Brian Seger

R.

Graphene oxide suspended in ethanol undergoes reduction as it accepts electrons from UV-irradiated TiO(2) suspensions. The reduction is accompanied by changes in the absorption of the graphene oxide, as the color of the suspension shifts from brown to black. The direct interaction between TiO(2) particles and graphene sheets hinders the collapse of exfoliated sheets of graphene. Solid films cast on a borosilicate glass gap separated by gold-sputtered terminations show an order of magnitude decrease in lateral resistance following reduction with the TiO(2) photocatalyst. The photocatalytic methodology not only provides an on-demand UV-assisted reduction technique but also opens up new ways to obtain photoactive graphene-semiconductor composites.

The use of a 2-D carbon nanostructure, graphene, as a support material for the dispersion of Pt nanoparticles provides new ways to develop advanced electrocatalyst materials for fuel cells. Platinum nanoparticles are deposited onto graphene sheets by means of borohydride reduction of H2PtCl6 in a graphene oxide (GO) suspension. The partially reduced GO-Pt catalyst is deposited as films onto glassy carbon and carbon Toray paper by drop cast or electrophoretic deposition methods. Nearly 80% enhancement in the electrochemically active surface area (ECSA) can be achieved by exposing partially reduced GO-Pt films with hydrazine followed by heat treatment (300 °C, 8 h). The electrocatalyst performance as evaluated from the hydrogen fuel cell demonstrates the role of graphene as an effective support material in the development of an electrocatalyst.

Renewed interest in graphene architectures has opened up new avenues to utilize them in electronic and optoelectronic applications. The desire to design graphene−metal nanohybrid assemblies has led us to explore a solution-based approach of chemical reduction of AuCl4- ions in graphene suspensions. The gold particles anchored on octadecylamine functionalized graphene are readily suspendable in THF medium. The dependence of particle stability on the graphene concentration and SEM analysis indicate that the gold nanoparticles are well dispersed on graphene sheets. Transient absorption spectroscopy measurements suggest that the ultrafast disappearance of plasmon absorption and its recovery are unaffected by the presence of graphene.

Field-sensitive electrochemical reactions are controlled by electrode charging which is sensitive to the size of the electrolyte containing cations.