Synergistic Interlayer and Defect Engineering in VS₂ Nanosheets toward Efficient Electrocatalytic Hydrogen Evolution Reaction

Abstract

A simple one-pot solvothermal method is reported to synthesize VS nanosheets featuring rich defects and an expanded (001) interlayer spacing as large as 1.00 nm, which is a ≈74% expansion as relative to that (0.575 nm) of the pristine counterpart. The interlayer-expanded VS nanosheets show extraordinary kinetic metrics for electrocatalytic hydrogen evolution reaction (HER), exhibiting a low overpotential of 43 mV at a geometric current density of 10 mA cm , a small Tafel slope of 36 mV dec , and long-term stability of 60 h without any current fading. The performance is much better than that of the pristine VS with a normal interlayer spacing, and even comparable to that of the commercial Pt/C electrocatalyst. The outstanding electrocatalytic activity is attributed to the expanded interlayer distance and the generated rich defects. Increased numbers of exposed active sites and modified electronic structures are achieved, resulting in an optimal free energy of hydrogen adsorption (∆G ) from density functional theory calculations. This work opens up a new door for developing transition-metal dichalcogenide nanosheets as high active HER electrocatalysts by interlayer and defect engineering.

Defect‐Rich Heterogeneous MoS2/NiS2 Nanosheets Electrocatalysts for Efficient Overall Water Splitting

“…[8,33] For S 2p spectra in obtained samples (Figure 3d), it can be deconvoluted into three peaks corresponding to the S 2p 3/2 , S 2p 1/2 for Mo-S bond and S 2p 1/2 for Ni-S bond, at as well as a peak from the oxidized species formed on the surface of metal sulfides. [35,36] Based on SEM, TEM, Raman, and XPS analysis, as-synthesized MoS 2 /NiS 2 nanosheets are proved to possess porous nanostructure and defected interface for rich active sites and are expected to achieve excellent electrocatalytic performances. [34,35] It suggests the presence of terminal unsaturated S atoms on Mo-S and Ni-S sites, which may be beneficial for HER performances.…”

2D Metallic Transitional Metal Dichalcogenides for Electrochemical Hydrogen Evolution

“…Colloidal synthesis is an efficient route for the large‐scale production of TMDC nanosheets with low cost. Recently, this method has also been applied to synthesize MTMDC nanosheets (e.g., VS 2 , VSe 2 , etc.) and the related heterostructures (e.g., VS 2 /reduced graphene oxide [rGO] hybrids, etc.).…”

“…A summary of the colloidal synthesis methods of 2D MTMDCs is presented in Table . In a typical example, VS 2 nanosheeets were hydrothermally synthesized by using vanadate (NH 4 VO 3 , Na 3 VO 4 ) and thioacetamide (C 2 H 5 NS) as precursors. Particularly, Wang's group directly synthesized vertical VS 2 nanoplate arrays (≈30 nm in thickness, ≈800 nm in lateral dimension) on a carbon paper by the hydrothermal reaction between Na 3 VO 4 ·10H 2 O and C 2 H 5 NS in the aqueous solution …”

“…g) Polarization curves and h) corresponding Tafel plots of the solvothermal‐synthesized 1T‐VS 2 , the annealed solvothermal‐synthesized 1T‐VS 2 , and the hydrothermal 1T‐VS 2 . Reproduced with permission . Copyright 2018, Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim.…”

“…To further enhance the HER performance, Lu and co‐workers synthesized interlayer‐expanded 1T‐VS 2 nanosheets with diameters of ≈2 μm through a one‐pot solvothermal route . The interlayer spacing (≈1.00 nm) of the solvothermal‐synthesized 1T‐VS 2 exhibited a ≈74% expansion as compared with that of pristine bulk 1T‐VS 2 (0.575 nm) (Figure e).…”