Sugar-Based Natural Deep Eutectic Mixtures as Green Intercalating Solvents for High-Yield Preparation of Stable MoS₂ Nanosheets: Application to Electrocatalysis of Hydrogen Evolution Reaction

Abstract

Wide applicability of nanosized MoS 2 in diverse research fields including optoelectronics, biomedicine, energy storage, and conversion is a motivation for investing efforts in green, low-cost, and efficient synthesis of these nanomaterials. To date, various methods for the synthesis of MoS 2 nanosheets have been reported, most of which use toxic organic solvents in appreciable amounts. In the present report, we introduced a mechanical exfoliation approach in which bulk MoS 2 is converted to two-dimensional nanosheets with a yield as high as 44%. We used sugar-based natural deep eutectic solvents (NADESs) as intercalating solvents and a reusable 5 mL glass syringe as an exfoliation chamber to achieve this purpose. Using the present approach, we were able to tune the thickness, length, and concentration of the nanosheets by changing experimental parameters. Under the optimized experimental conditions and based on their UV−vis absorption spectrum, the average thickness and length of the nanosheets exfoliated by NADES 1 were estimated as 4 and 150 nm, respectively. The nanosheets were mixed phase (2H−1T) with 2H/1T ratio of 1.4. They were electrocatalytically active in hydrogen evolution reaction. We achieved the overpotential of 0.339 V versus reversible hydrogen electrode at the current density of 10 mA/cm 2 and long-term durability in acidic media. Furthermore, the synthesized MoS 2 nanosheets were stable in ethanol/water, water, and various cell culture media for a prolonged time. The designed experimental setup in the present report is low-cost and very easy to assemble. Most notably, the use of NADESs as the green exfoliation solvents fulfills the principles of green chemistry as they have no environmental impacts. We believe that owing to the green nature of the solvent, cost efficiency, and the high-yield characteristic of the method, it has the potential to be employed in an industrial scale.

Deep Eutectic Solvents for Boosting Electrochemical Energy Storage and Conversion: A Review and Perspective

“…[102][103][104][105] Besides, DESs have attracted interest in exfoliating layered nanomaterials. [106] It should be noted that the study of using DES to prepare new materials is still in its infancy, especially for those related to energy storage applications. In this section, we focus on discussing the synthesis of functional materials with DESs for energy storage applications.…”

“…Mohammadpour et al developed DESs based on natural sugar as green intercalating solvents for the preparation of stable dispersion of MoS 2 nanosheets. [106] Recently, they found that water can modulate the molecular arrangement of this DES and can effectively regulate the efficiency of preparing both MoS 2 and graphene nanosheets. [126] Besides, Sang and co-workers applied a DES composed of ChCl and EG with a molar ratio of 1:2 to exfoliate a layered metal-organic framework (i.e., MAMS-1).…”

Green and Non‐conventional Extraction of Bioactive Compounds from Olive Leaves: Screening of Novel Natural Deep Eutectic Solvents and Investigation of Process Parameters

“…Choline chloride was dried under vacuum over silica gel in a desiccator prior to use. The NADESs prepared and used in this study are as follows: glucose-fructose-sucrose-water (1:1:1:11) (GFSW), glucose-fructose-water (1:1:11) (GFW), glucose-sucrose-water (1:1:11) (GSW), fructose-sucrose-water (1:1:11) (FSW) [54], choline chloride (ChCl)-glucose-water (5:2:5) (CGW), ChCl-fructose-water (5:2:5) (CFW), ChCl-sucrose-water (4:1:4) (CSW) [55], ChCl-lactic acid (1:2) (CLa) [44], ChCl-malonic acid (1:1) (CMa) [55], ChCl-ethylene glycol (1:2) (CEG) [38] and ChCl-glycerol (1:2) (CGly) [56].…”

2D nanosheet enabled thin film nanocomposite membranes for freshwater production – a review

“…14 To tackle the compatibility and stability factors, several additional studies were conducted to prepare functionalized MoS 2 nanosheets. 79,[81][82][83] Accordingly, high efficiency polyphenol assisted liquid exfoliation was used as a green method to produce layered MoS 2 nanosheets with tannic acid (TA-MoS 2 ). 83 Due to their improved stability and compatibility, TA-MoS 2 nanosheets were successfully incorporated into the polyamide layer, forming a TFN NF membrane with superior performance.…”