Exfoliation of 2D Materials for Energy and Environmental Applications

Abstract

The fascinating properties of single‐layer graphene isolated by mechanical exfoliation have inspired extensive research efforts toward two‐dimensional (2D) materials. Layered compounds serve as precursors for atomically thin 2D materials (briefly, 2D nanomaterials) owing to their strong intraplane chemical bonding but weak interplane van der Waals interactions. There are newly emerging 2D materials beyond graphene, and it is becoming increasingly important to develop cost‐effective, scalable methods for producing 2D nanomaterials with controlled microstructures and properties. The variety of developed synthetic techniques can be categorized into two classes: bottom‐up and top‐down approaches. Of top‐down approaches, the exfoliation of bulk 2D materials into single or few layers is the most common. This review highlights chemical and physical exfoliation methods that allow for the production of 2D nanomaterials in large quantities. In addition, remarkable examples of utilizing exfoliated 2D nanomaterials in energy and environmental applications are introduced.

Intercalation as a versatile tool for fabrication, property tuning, and phase transitions in 2D materials

“…Different intercalationassisted methods have been utilized to fabricate 2D materials such as oxidation-based intercalation and exfoliation [68][69][70][71][72][73][74] , reductionbased intercalation and exfoliation 69,[75][76][77][78][79][80] , and ion-exchanged intercalation and exfoliation 81,82 . A list of such fabrication methods compared with other methods [83][84][85][86][87][88][89] of fabrication of 2D materials are presented in Table 1. In oxidation-based intercalation, a strong oxidative agent is used to oxidize and intercalate the layered host material to expand the interlayer spacing; thus, the material can be exfoliated to thin flakes more easily by shear force or gas production reaction.…”

Fire-Safe Polymer Composites: Flame-Retardant Effect of Nanofillers

“…This is because they have a high thermal stability, strong barrier effect, and large specific surface adsorption capability, which are favorable for reducing heat and mass transfer [ 101 , 184 ]. Many studies have proven that graphene and its derivatives can have significant effects on the pyrolysis of polymers [ 36 , 98 , 99 , 185 ], as well as on their thermal conductivity, heat absorption, and dripping [ 184 , 185 , 186 , 187 ]. This suggests that they could be powerful flame retardants because they can ameliorate the polymer thermal stability and delay its ignition; furthermore, they can inhibit the fire from spreading and reduce the HRR [ 188 ].…”

“…The fabrication of MoS 2 @TiO 2 nanosheets involved two simple processes ( Figure 33 ) [ 232 ]. First, layered bulk MoS 2 was exfoliated into single- or few-layer sheets with the help of hydrogen gas generated by the reaction of lithium ions intercalated between the MoS 2 layers with water [ 100 , 187 ]. Second, the hydrolysis of tetrabutyl titanate via a solvothermal method yielded MoS 2 @TiO 2 nanosheets by the in situ nucleation and growth of TiO 2 nanosheets on the surface of the exfoliated MoS 2 .…”

Recent Progress on Molecular Photoacoustic Imaging with Carbon-Based Nanocomposites

“…Two-dimensional materials have received great interest and broadened their scope of application in the fields of energy storage, energy conversion, sensing, and catalysis [ 116 , 117 ]. Recently, Li et al reported nanotransducers that can provide simultaneous PA imaging and photothermal therapy using graphdiyne (GDY), a two-dimensional carbon-based network comprised of benzene rings and acetylene linkages [ 118 ].…”