AVS 59th Annual International Symposium and Exhibition
    Surface Science Tuesday Sessions
       Session SS-TuP

Paper SS-TuP3
MORTON S. TRAUM AWARD FINALIST: Understanding Molecular Adsorption on Graphene-based Hybrid Nanostructures by In Situ Infrared Microspectroscopy

Tuesday, October 30, 2012, 6:00 pm, Room Central Hall

Session: Surface Science Poster Session
Presenter: E. Mattson, University of Wisconsin Milwaukee
Authors: E. Mattson, University of Wisconsin Milwaukee
S. Cui, University of Wisconsin Milwaukee
K. Pande, University of Wisconsin Milwaukee
H. Pu, University of Wisconsin Milwaukee
M. Schofield, University of Wisconsin Milwaukee
G. Lu, University of Wisconsin Milwaukee
M. Weinert, University of Wisconsin Milwaukee
M. Gajdardziska-Josifovska, University of Wisconsin Milwaukee
J. Chen, University of Wisconsin Milwaukee
C. Hirschmugl, University of Wisconsin Milwaukee
Correspondent: Click to Email
Graphene is an emerging platform for many applications, and being a strictly two-dimensional material, is particularly sensitive to atomic and molecular adsorption. These characteristics have made graphene-based materials a rising candidate for sensing applications targeting harmful chemicals which pollute our living environment. While under ideal ultra high vacuum (UHV) conditions, graphene monolayers have demonstrated single molecule detection sensitivity, such performance is not feasible under realistic operating conditions. To further improve sensitivity of graphene towards gas detection, we have performed controlled functionalization of graphene with oxygen and decoration with nanoparticles (NPs), where the graphene films act as a sensitive conduction channel, while oxygen functional groups, defects and NPs provide active adsorption sites. While these materials yield impressive performance, little is known about the chemical nature of the substrate/adsorbate interactions. To this end, we have performed in situ synchrotron-based infrared microspectroscopy (IRMS) on these atomically thin, micrometer-scale hybrid graphene materials during exposure to the environmentally significant gases NO2 and NH3 under normal working conditions (e.g., atmospheric pressure at low concentrations of target gases). Under such conditions, native functional groups are naturally present on the hybrid surfaces and may in fact contribute to the sensing processes. We have investigated hybrid sensing materials consisting of both chemically and thermally reduced graphene oxide (RGO) and chemically RGO decorated with tin dioxide NPs using transmission electron microscopy (TEM) and synchrotron-based IRMS. Experiments were performed at the synchrotron radiation center (SRC) in Stoughton, WI using the recently commissioned infrared environmental imaging (IRENI) beamline. Our studies of the as-produced materials have identified the native functional groups at the hybrid surfaces which are present under normal working conditions. As-produced chemically reduced GO contains functional groups due to residual carbonyl and epoxide species, while SnO2-decorated RGO contains surface hydroxyl groups, adsorbed water and surface carbonyl groups. We then performed in situ IRMS upon exposure to gases to identify the chemical nature of the adsorbates and the resulting changes in the surface composition and electronic properties of the substrate materials. In situ IRMS results for NH3 and NO2 adsorption on RGO and SnO2-decorated RGO will be presented.