Hypervalent Iodine Compounds as Versatile Reagents for Extremely Efficient and Reversible Patterning of Graphene with Nanoscale Precision

Abstract

Rational patterning and tailoring of graphene relies on the disclosure of suitable reagents for structuring the target functionalities on the 2D‐carbon network. Here, a series of hypervalent iodine compounds, namely, 1‐chloro‐1,2‐benziodoxol‐3(1H)‐one, 1,3‐dihydro‐1‐hydroxy‐3,3‐dimethyl‐1,2‐benziodoxole, and 3,3‐dimethyl‐1‐(trifluoromethyl)‐1,2‐benziodoxole is reported to be extremely efficient for a diversified graphene patterning. The decomposition of these compounds generates highly reactive Cl, OH, and CF3 radicals exclusively in the irradiated areas, which subsequently attach onto the graphene leading to locally controlled chlorination, hydroxylation, and trifluoromethylation, respectively. This is the first realization of a patterned hydroxylation of graphene, and the degrees of functionalization of the patterned chlorination and trifluoromethylation are both unprecedented. The usage of these mild reagents here is reasonably facile compared to the reported methods using hazardous Cl2 or ICl and allows for sophisticated pattern designs with nanoscale precision, promising for arbitrary nanomanipulation of graphene's properties like hydrophilicity and conductivity by the three distinct functionalities (Cl, OH, and CF3). Moreover, the attachment of functional entities to these highly functionalized graphene nanoarchitectures is fully reversible upon thermal annealing, enabling a full writing/storing/reading/erasing control over the chemical information stored within graphene. This work provides an exciting clue for target 2D functionalization and modulation of graphene by using suitable hypervalent iodine compounds.

Molecular Stacking on Graphene

“…[12,21] In general, the The AFM topography shows negligible height variations between the patterned regions and unpatterned regions, which is most likely attributed to the introduction of the small sized ethylpyridine groups (less than 0.5 nm in height), consistent with previous studies. [12,15,16] However, the pattern exemplified by the letter of "F" can be clearly visualized by KPFM due to the alteration of the surface potential of the patterned regions stemming from the chemical binding of the ethylpyridine addends. Owing to the electron-donating nature of the ethylpyridine moiety and the resulting ndoping effect, the patterned regions exhibit a higher surface potential of ca.…”

Covalent Patterning of Graphene for Controllable Functionalization from Microscale to Nanoscale: A Mini-Review

“…Besides using diazonium salts as radical sources, hypervalent iodine compounds have also been applied for covalent functionalization of graphene. Bao et al, (2021 ) applied a laser-writing process for covalent patterning of the graphene substrate. A drop of hypervalent iodine solution was first deposited on a SiO 2 /Si-supported graphene.…”

Spatial Control of Graphene Functionalization by Patterning a 2D Substrate: Implications for Graphene Based van-der-Waals Heterostructures

“…This will allow spatial patterning of graphene into neighboring regions with different physical properties or chemical functions, which may open entirely new ways for fabricating graphene devices. Various approaches, such as ozone treatment, using PMMA (poly­(methyl methacrylate)) masks on top, , applying masked or mask-free plasma jets, , producing reactive radicals under laser irradiation, − or providing the chemical compounds in channels underneath the graphene sheet, have already been used to obtain spatial patterns of functionalized graphene. Furthermore, well-defined nanoscale patterns using aryldiazonium chemistry have been achieved by self-assembled alkane monolayers as templating masks, by nanomanipulation with ambient scanning tunneling microscopy (STM) after functionalization, or through ordering of aryl diazonium salts .…”