Toward Understanding the Efficient Exfoliation of Layered Materials by Water-Assisted Cosolvent Liquid-Phase Exfoliation

Abstract

Preparation of two-dimensional layered materials (2DLM) nanosheets is critical for both fundamental studies and applications. Here we present a systematic study to explore the fundamental factors to control the exfoliation of graphite and MoS2 in aqueous N-methylpyrrolidinone (NMP) using water as the cosolvent. Detailed materials characterizations suggested that the cosolvency significantly influences the yield and the stability of exfoliated nanosheets. The dependence of exfoliation on cosolvency was examined by fundamental factors including solid–liquid interfacial parameters, Hansen Solubility Parameter (HSP), and intermolecular-interaction-sensitive physical parameters of the water–NMP mixed solvent system. Fourier transform infrared spectroscopy (FTIR) study revealed that the water–NMP heteroassociated molecular structures, formed with the addition of water to NMP, could play an important role in the liquid exfoliation of layered materials. Our work provides a guide to rational design of a solvent system to improve the yield and stability of the exfoliated materials.

Towards understanding the salt-intercalation exfoliation of graphite into graphene

“…16 However, this method involves the ultrasonic treatment of graphite in solvents such as N-methyl-2-pyrrolidone (NMP), N,N-dimethylformamide (DMF), and gbutyrolactone (GBL). [17][18][19] These solvents are expensive and require special care during handling, meaning that this method is not safe, user-friendly or environmentally friendly.…”

Enhanced Lithium Storage Performance of Liquid‐Phase Exfoliated Graphene Supported WS2 Heterojunctions

“…Figure showed the procedure to synthesize LEGr@WS 2 hybrids. First, LEGr was obtained in high yields following a modified literature method via the liquid‐phase exfoliation of natural graphite flakes in NMP with the help of the sodium citrate and water ,. LEGr@WS 2 hybrids were fabricated by a microwave‐assisted solvothermal method using the exfoliated LEGr as the substrates; WCl 6 and sulfur as the precursors; and 1‐dodecanethiol and sodium citrate as the surfactant and reducing agent, respectively.…”

Recent Progress in Synaptic Devices Based on 2D Materials

“…By liquid exfoliation methods or wet chemical synthesis methods, various 2D flakes could be prepared in mass production; however, external ions or compounds are inevitable involved in the synthesis, and the domain size of the 2D materials ranges from only tens to hundreds of nanometers. Moreover, the thicknesses, morphology, and size of flakes are difficult to control …”