Infrared and Raman spectroscopic analysis of functionalized graphene

Abstract

In this mini‐review, we discuss our work in the analysis of material properties of electrochemically functionalized graphene using infrared (IR) and Raman techniques as thin film sensitive vibrational spectroscopies. Multiscale characterization is demonstrated using a combination of IR spectroscopic ellipsometry (IRSE), confocal Raman spectroscopy (RS) and photothermal atomic force microscopy coupled IR analysis (AFM‐IR). IRSE is used for spots with dimensions of a few mm, RS for spots with a diameter of a few micrometer and AFM‐IR at the sub‐100 nm scale. In the first part of the article, functionalized large‐area graphene sheets electrochemically modified by ultrathin oligomer films of maleimidophenyl or 4‐aminophenyl acetic acid are studied. Characteristic molecular vibrations of the functional layers are analyzed by the IR methods, while the graphene‐related phonons are characterized by RS. This dual approach allowed for the determination of the attached functional groups as well as the identification of the nature of chemical coupling of the functional moieties to graphene. The thickness of the deposited layers extracted from IRSE data correlates very well with AFM measurements. In the second part of the article, functionalized graphene sheets are characterized by correlative vibrational optical spectroscopy directly at a device level.

Quantum Dot Modification of Large Area Graphene Surfaces via Amide Bonding

“…Among those, the electrochemical reduction of aryl diazonium salts is a common method to introduce covalently bound functional groups. [22][23][24][25][26][27]28] Major advantages of this kind of functionalization are the vast number of functional groups to select from, the low thickness of the functional layer, which is typically equivalent to a range of one to five molecular layers, as well as the covalent nature of the formed bond between the graphene lattice and the aryl residue. The latter is often considered a compromise, as the strong bonding is accompanied by the formation of sp 3 -defects in the graphene lattice.…”

“…The latter is often considered a compromise, as the strong bonding is accompanied by the formation of sp 3 -defects in the graphene lattice. [28] In this paper, a route is described that shows how graphene is modified by covalently binding QDs with a diameter of ≈6 nm to its surface. Subsequently, these layers are transferred to a desired substrate while preserving the light-emitting properties of the QDs.…”

“…The latter is often considered a compromise, as the strong bonding is accompanied by the formation of sp 3 ‐defects in the graphene lattice. [ 28 ]…”

Carbon Nitride Grafting Modification of Poly(lactic acid) to Maximize UV Protection and Mechanical Properties for Packaging Applications

“…Interestingly, the residual −NH 2 or −NH groups in g-C 3 N 4 can be used as active sites for amidation reactions or to form hydrogen bonds with other functional groups such as −SH, −OH, or −COOH. − Grafting postpolymerization modification is thus possible, , making g-C 3 N 4 a promising nanofiller for better compatibility with polymers. Given that g-C 3 N 4 is structurally similar to graphene, it is expected that the combination of g-C 3 N 4 with polar polymer molecules can positively improve the thermal stability and mechanical properties of the polymer matrix.…”