Designing Champion Nanostructures of Tungsten Dichalcogenides for Electrocatalytic Hydrogen Evolution

Abstract

Fine‐tuning strain and vacancies in 2H‐phase transition‐metal dichalcogenides, although extremely challenging, is crucial for activating the inert basal plane for boosting the hydrogen evolution reaction (HER). Here, atomically curved 2H‐WS2 nanosheets with precisely tunable strain and sulfur vacancies (S‐vacancies) along with rich edge sites are synthesized via a one‐step approach by harnessing geometric constraints. The approach is based on the confined epitaxy growth of WS2 in ordered mesoporous graphene derived from nanocrystal superlattices. The spherical curvature imposed by the graphitic mesopores enables the generation of uniform strain and S‐vacancies in the as‐grown WS2 nanosheets, and simultaneous manipulation of these two key parameters can be realized by simply adjusting the pore size. In addition, the formation of unique mesoporous WS2@graphene van der Waals heterostructures ensures the ready access of active sites. Fine‐tuning the WS2 layer number, strain, and S‐vacancies enables arguably the best‐performing HER 2H‐WS2 electrocatalysts ever reported. Density functional theory calculations indicate that compared with strain, S‐vacancies play a more critical role in enhancing the HER activity.

A Polarization Boosted Strategy for the Modification of Transition Metal Dichalcogenides as Electrocatalysts for Water‐Splitting

“…[10] Various strategies including morphology regulation, [11] crystal phase engineering, [12][13][14][15][16] and doping with other elements [17] have been put forward to solve the problems and to fabricate the benign bifunctional electrocatalysts. As expected, many modified TMDs-based composites, especially WS 2 -based electrocatalysts have been prepared, such as, WS 2 @graphene, [18] Mo 0.5 W 0.5 S 2, [19] 1T'-D WS 2 , [20] WS 2 nanodots, [21] Co-doped WS 2 /W 18 O 49 nanotubes [22] and N,P co-doped exfoliated WS 2 . [23] Among them, tuning the polarization effect of the components to achieve better conductivity has drawn increasing attentions for the enhancement of water-splitting performance.…”

Electrocatalytic Hydrogen Evolution Reaction Related to Nanochannel Materials

“…[65] The 2D/2D vdW heterostructures with face-to-face contact could build a kind of highly coupled interface, which may largely improve the catalytic activity. [66] For example, Zhang and co-workers have fabricated a heterostructure with alternatively arranged ultrasmall monolayer MoS 2 nanosheets and ultrathin graphene (Figure 5b). [25] The density functional theory calculation illustrates an expanded interplanar distance of the heterostructure (1.104 nm) compared to that of pristine MoS 2 (0.615 nm).…”

Metallic Transition Metal Dichalcogenides of Group VIB: Preparation, Stabilization, and Energy Applications

“…Very recently, Han et al proposed a design of champion nanostructure for 2H phase WS 2 @graphene by using epitaxy growth method and tested the HER performance. [288] This structure subtly squeezes the values of strain, sulfur vacancies and graphene. Strain and S-vacancies could not only provide more active sites but also lower the energy gaps, whereas graphene is responsible for the conductivity and durability.…”