Regensburg 2019 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 9: Graphene I: Structure and Growth (joint session O/TT)
TT 9.8: Talk
Monday, April 1, 2019, 12:30–12:45, H24
Thermal reduction of graphene oxide studied by electron spectroscopy — •Gianluca Di Filippo1, Andrea Liscio2, and Alessandro Ruocco1 — 1Dipartimento di Scienze, Università degli Studi Roma Tre, Rome, Italy — 2Consiglio Nazionale delle Ricerche, Istituto per la Microelettronica e Microsistemi, Rome, Italy
Graphene oxide (GO) is a purely 2D material composed of a conductive filter given by sp2 domains and an insulating matrix containing sp3-carbons, defects, holes and oxygen functional groups. The latter make GO an insulator, but its electronic, optical and structural properties can be tailored via controlled removal of the oxygen groups. This enables reduced graphene oxide (rGO) to be used in many fields such as sensors development and energy storage applications.
In this work, we investigated the thermal reduction of GO in ultra-high-vacuum by combining several electron spectroscopies.
Photoemission spectroscopy (XPS and UPS) was used to investigate variations in the chemical and electronic structure of GO reduced in the 150 ∘C - 750 ∘C temperature range.
The optical properties of rGO were investigated using electron energy loss spectroscopy (EELS). The build-up of the π−plasmon excitation was observed upon reduction at 300 ∘C, this revealing the formation of ordered graphene-like areas with dimensions around 5 nm. The vibrational spectrum revealed the presence of CH groups on the surface. Most of the hydrogen atoms are bound to sp3-carbon and are probably located in oxidized regions in the basal plane of rGO. The sp3-CH impurities can be removed upon annealing at 750 ∘C where only sp2 CH defects are observed.