Review of the role of ionic liquids in two-dimensional materials

Abstract

Ionic liquids (ILs) are expected to be used as readily available “designer” solvents, characterized by a number of tunable properties that can be obtained by modulating anion and cation combinations and ion chain lengths. Among them, its high ionicity is outstanding in the preparation and property modulation of two-dimensional (2D) materials. In this review, we mainly focus on the ILs-assisted exfoliation of 2D materials towards large-scale as well as functionalization. Meanwhile, electric-field controlled ILs-gating of 2D material systems have shown novel electronic, magnetic, optical and superconducting properties, attracting a broad range of scientific research activities. Moreover, ILs have also been extensively applied in various field practically. We summarize the recent developments of ILs modified 2D material systems from the electrochemical, solar cells and photocatalysis aspects, discuss their advantages and possibilities as “designer solvent”. It is believed that the design of ILs accompanying with diverse 2D materials will not only solve several scientific problems but also enrich materials design and engineer of 2D materials.

Graphical abstract

Keywords

ionic liquids / two-dimensional materials / liquid phase exfoliation / ionic liquid-gating / electrochemical capacitors / solar cells / photocatalysis

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Acknowledgements

This work was supported by the Natural Science Foundation of Fujian Province of China (No. 2022J01007), the Fundamental Research Funds for Central Universities (Grant No. 20720210018), and the National Natural Science Foundation of China (No. 11704317).

Abbreviations

Cations of ILs
[BMIM]	1-butyl-3-methylimidazolium
[EMIM]	1-ethyl-3-methylimidazolium

Anions of ILs
[PF6]	hexafluorophosphate
[BF4]	tetrafluoroborate
[TFSI] or [NTf2]	bis(trifluoromethylsulfonyl) imide

Other
ILs	Ionic liquids
2D materials	two-dimensional materials
TMDs	transition metal dichalcogenide
MoS2	molybdenum disulfide
MoSe2	Molybdenum(IV) selenide
MoTe2	Molybdenum Ditelluride
WS2	Tungsten disulfide
WSe2	Tungsten(IV) selenide
ReS2	Rhenium Disulfide
TaS2	tantalum disulfide
NMDs	noble metal dichalcogenides
PdSe2	Palladium diselenide
PtSe2	Platina Diselenide
PtS2	Platinum disulfide
h-BN	hexanol boron nitride
BP	black phosphorus
LDHs	layered double hydroxide
g-C3N4	graphite carbon nitrides
MOFs	metal-organic frameworks
COFs	covalent-organic frameworks
LPE	liquid phase exfoliation
NMP	N-methylpyrrolidone
N12P	1-dodecyl-2-pyrrolidone
(P[VBTP][Cl])	poly(triphenyl-4-vinylbenzylphosphonium chloride)
(P[VimBu][Br])	poly(3-N-butyl-1-vinylimidazolium bromide)
(PNIL)	(poly(N-isopropylacrylamide-co-IL)
FG	fluorinated graphene
EDLTs	electrical double-layer transistors
FETs	field-effect transistors
CNT	carbon nanotubes
SS	subthreshold swing
CDW	charge-density-wave
Cr2Ge2Te6	Chromium germanium tellurium
m-CTF	microporous covalent triazine structure
rGO	reduced graphene oxide
aMEGO	activated microwave exfoliated graphene oxide
GNS	2D graphene nanosheets
GO	graphite oxide
(EMI-TFSI)	1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide
Ti3C2Tx	Titanium carbide
MSCs	micro-supercapacitors
AA-Ti3C2	AA-cation-intercalated Ti3C2Tx
EMIM-TFSI	1-ethly-3-methylimidazolium bis-(trifluoromethylsulfonyl)-imide
DMIM	1,3-dimethyl-3-imidazolium
Cs0.08FA0.92PbI3	formamidinium-cesium lead iodide perovskite
[Hnmp]Cl	[N-methyl-pyrrolidonium] chloride
Bi2O2CO3	Bismuth subcarbonate
Bi2Se3	bismuth selenide
[C16mim]Br	1-hexadecyl-3-methylimidazole bromide
Bi2MoO6	Bismuth molybdenum oxide
Bi2WO6	Bismuth tungstate

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