Liquid Phase Exfoliation of MoS₂ Assisted by Formamide Solvothermal Treatment and Enhanced Electrocatalytic Activity Based on (H₃Mo₁₂O₄₀P/MoS₂)_n Multilayer Structure

Abstract

In this work, MoS2 nanosheets were obtained successfully using the liquid phase exfoliation method assisted by formamide solvothermal treatment. The exfoliation efficiency in N-methyl-2-pyrrolidone (NMP) was enhanced by the synergetic effect of easier intercalation of polar solvent and higher repulsive force of the treated bulk MoS2. The exfoliated MoS2 nanosheets were assembled alternately with H3Mo12O40P (PMo12) into a multilayer heterostructure by the layer-by-layer (LBL) method, in which PMo12 with high electron mobility bridges the adjacent catalytically active MoS2 layers. Based on the heterostructure, the electrocatalytic performance for hydrogen evolution was substantially enhanced over multilayer MoS2 nanosheets alone. Moreover, it was found that the electrocatalytic performance was influenced by the layer number, indicating that an optimum balance between the mass transfer (MoS2 layer) and electron conductivity (PMo12 layer) was needed for the construction of efficient electrocatalysts. In addition, the electrocatalytic performance of the multilayers (MoS2)n and (PMo12/MoS2)n could be improved by oxygen plasma treatment, which might be ascribed to the increased number of edges and defects in MoS2 nanosheets. This work not only provides a facile method to exfoliate MoS2 with higher efficiency, but also offers a feasible strategy to build up high-performance electrocatalysts by rationally assembling nanosheets and polyoxometalate species at the nanoscale level.

Production and Patterning of Liquid Phase–Exfoliated 2D Sheets for Applications in Optoelectronics

“…In recent study, Huang et al demonstrated liquid phase exfoliation of MoS 2 assisted by formamide solvothermal treatment. Bulk MoS 2 was pretreated in formamide in an autoclave for 48 h at different temperatures of 120–140 °C.…”

Graphene to Advanced MoS2: A Review of Structure, Synthesis, and Optoelectronic Device Application

“…Via a range of experiments, Coleman et al [157] proposed the optimized solvents for MoS 2 and WS 2 . Different 2D materials have different surface energies, and consequently, different solvents are required to form the stable dispersions of different materials [162,163]. Precisely, the surface energies of MoS 2 , h-BN, and graphene are 46-65 mJ cm −2 , 44-66 mJ cm −2 , and 70 mJ cm −2 [157,164].…”

A Review on the Promising Plasma-Assisted Preparation of Electrocatalysts

“…The Tafel slope of O 2 –MoS 2 was up to 105 mV/dec, which was significantly better than Ar–MoS 2 (117 mV/dec) and MoS 2 (160 mV/dec). In 2018, Zhang et al [87] and Huang et al [88] found that MoO 3 species were formed at the edge and plane positions of MoS 2 by using O 2 plasma to treat MoS 2 and H 3 Mo 12 O 40 P/MoS 2 composite intercalation compounds respectively. The MoO 3 can also be reduced and decomposed from the lattice of MoS 2 in the HER catalytic process, effectively improving the HER catalytic activity of MoS 2 .…”