Mechanism of Bismuth Telluride Exfoliation in an Ionic Liquid Solvent

Abstract

Bismuth telluride (Bi2Te3) is a well-known thermoelectric material that has a layered crystal structure. Exfoliating Bi2Te3 to produce two-dimensional (2D) nanosheets is extremely important because the exfoliated nanosheets possess unique properties, which can potentially revolutionize several material technologies such as thermoelectrics, heterogeneous catalysts, and infrared detectors. In this work, ionic liquid (IL) 1-butyl-3-methylimidazolium chloride ([C4mim]Cl) is used to exfoliate Bi2Te3 nanoplatelets. In both experiments and in molecular dynamics (MD) simulations, the Bi2Te3 nanoplatelets yield a stable dispersion of 2D nanosheets in the IL solvent, and our MD simulations provide molecular-level insight into the kinetics and thermodynamics of the exfoliation process. An analysis of the dynamics of Bi2Te3 during exfoliation indicates that the relative translation (sliding apart) of adjacent layers caused by IL-induced forces plays an important role in the process. Moreover, an evaluation of the MD trajectories and electrostatic interactions indicates that the [C4mim](+) cation is primarily responsible for initiating Bi2Te3 layer sliding and separation, while the Cl(-) anion is less active. Overall, our combined experimental and computational investigation highlights the effectiveness of IL-assisted exfoliation, and the underlying molecular-level insights should accelerate the development of future exfoliation techniques for producing 2D chalcogenide materials.

Chemically exfoliating large sheets of phosphorene via choline chloride urea viscosity-tuning

“…With dilution of the CCU solvent, intercalation happens more readily than in a pure system due to solvation effects of the intercalant molecule on the bulk material. While prior work has demonstrated that higher powered sonication (>100 W) produces thin flakes using a pure, high-viscosity intercalant, we show here that highpowered sonication is not necessary for exfoliation if the species responsible for the exfoliation (in this case CCU) is diluted with a solvent such as ethanol [20,25]. In fact, highpowered sonication can be detrimental to the overall yield of large-area flakes, due to the sonication breaking down the larger-area flakes into nanosheets of smaller lateral dimensions [16].…”

“…The vial was then sonicated in a water bath at 20 W for 120 min. Mechanical agitation is typically performed in chemical exfoliation experiments to hasten the intercalation since unaided diffusion of the intercalating species is a slow process, where the input power used in prior work has exceeded 80 W; additionally, most intercalation reactions require increased heat to allow for a more 'fluid' solvent [24,25]. However, due to the reactivity of BP, for our experiments low-powered, room temperature mechanical agitation is selected as a means of increasing the speed of the intercalation of the CCU between the layers of bulk BP, while minimizing heat.…”

Emerging Trends in Phosphorene Fabrication towards Next Generation Devices

“…The quest for new exfoliating media is necessary to find environmental friendly solvents, thereby avoiding toxic and impractical solvents . Therefore, Sresht et al studied the LPE of phosphorene in the solvents dimethyl sulfoxide (DMSO), dimethylformamide (DMF), isopropyl alcohol (IPA), NMP and N‐cyclohexyl‐2‐pyrrolidone (CHP) using three molecular‐scale computer experiments to model the solvent–phosphorene interactions via atomistic force fields assisted by ab initio calculations and lattice dynamics.…”

Nanoscopic diffusion of water on a topological insulator

“…In the case of Bi 2 Te 3 on the other hand, it was shown that water adsorption is less pronounced than the adsorption of oxygen 26,36 , even though the reactivity of water with Bi 2 Te 3 is still under debate 26,27,37 . Except for the influence of adsorbates on the electronic structure, chemistry on TI surfaces has been largely ignored, even though it was shown that TIs hold great potential for sensing applications 38,39 and exfoliation in liquid environment has been used to obtain nanosheets with unique properties [40][41][42] . With respect to catalysis, the existence of TSS can modify the catalyst-adsorbate interactions 43 , e.g.…”