A Blueprint for the Synthesis and Characterization of Thiolated Graphene

Abstract

Graphene derivatization to either engineer its physical and chemical properties or overcome the problem of the facile synthesis of nanographenes is a subject of significant attention in the nanomaterials research community. In this paper, we propose a facile and scalable method for the synthesis of thiolated graphene via a two-step liquid-phase treatment of graphene oxide (GO). Employing the core-level methods, the introduction of up to 5.1 at.% of thiols is indicated with the simultaneous rise of the C/O ratio to 16.8. The crumpling of the graphene layer upon thiolation without its perforation is pointed out by microscopic and Raman studies. The conductance of thiolated graphene is revealed to be driven by the Mott hopping mechanism with the sheet resistance values of 2.15 kΩ/sq and dependable on the environment. The preliminary results on the chemiresistive effect of these films upon exposure to ethanol vapors in the mix with dry and humid air are shown. Finally, the work function value and valence band structure of thiolated graphene are analyzed. Taken together, the developed method and findings of the morphology and physics of the thiolated graphene guide the further application of this derivative in energy storage, sensing devices, and smart materials.

Manifesting Epoxide and Hydroxyl Groups in XPS Spectra and Valence Band of Graphene Derivatives

“…On the other hand, two peaks with BE s of 288.2 eV and 288.9 eV corresponded to edge-located ketone and carboxyl groups, as has been signified by a number of synchrotron studies of GO and other graphene derivatives [ 52 , 53 ]. Moving to the epoxide and hydroxyl groups, the common contribution of carbon atoms participating in these functionalities was modeled by only one Gauss–Lorentz contour (C-OH and C-O-C peak) [ 35 , 51 , 52 ]. This arose from two factors: (i) a rather large FWHM of all the GO C 1 s spectral components derived during deconvolution, which as a rule noticeably exceeded 1.0 eV, and (ii) a relatively small difference in the predicted BE s of the C-OH and C-O-C components in the C 1 s spectra, commonly estimated to be less than 0.2–0.3 eV [ 54 , 55 , 56 ].…”

“…Recently, we have revealed the appearance of a set of localized molecular-related states in graphene’s VB upon its derivatization by carboxyl groups and ketones [ 34 ], as the most stable oxygen groups in GO. In turn, no substantial effect of basal-plane thiol groups on the DOS of the graphene layer has been identified for the thiolated graphene [ 35 ]. However, no insight into the localized states introduced by hydroxyls and epoxides, abundant in GO but sufficiently unstable to external factors, has been proposed yet.…”

“…Herein, taking advantage of our recent advances in XPS and theoretical studies of other graphene derivatives [ 34 , 35 ], the fingerprints of epoxide and hydroxyl groups in the C 1 s XPS and C K XAS spectra, as well as the molecular-related states in the valence band (VB), are revealed via the systematic study of diversely oxidized graphene layers by a set of spectroscopic methods complemented by density functional theory (DFT) modeling. Based on the comparative study of the XPS spectra with the NMR and infrared (IR) spectroscopy data, the distinctive spectral components related to the epoxide and hydroxyl groups were discerned and characterized in the C 1 s spectra.…”

Adaptive Peptide Molecule as the Promising Highly-Efficient Gas-Sensor Material: In Silico Study

“…Several strategies have been considered to overcome this issue. There are extensive applications of structural patterning and derivatization of carbon nanomaterials by certain functional groups to increase their affinity to a desired group of gases or volatile organic compounds (VOCs) over others [8,11,12]. Another approach to achieve distinctive detection of analytes is to apply such sets of derivatized carbon nanomaterials to fabricate a cross-reactive chemical sensor array or an on-chip multisensor array, forming biomimetic electronic noses (e-noses) [13][14][15].…”