Tailoring Polymorphic Heterostructures of MoS₂–WS₂ (1T/1T, 2H/2H) for Efficient Hydrogen Evolution Reaction

Abstract

Earth-abundant and inexpensive transition metal dichalcogenides (TMDCs) with existing polymorphisms (metallic 1T phase and semiconducting 2H phase) have been proposed as alternatives to noble metals (e.g., Pt, Ir, and Ru) to achieve an efficient hydrogen evolution reaction (HER). Although the 1T phase of TMDCs (1T-TMDCs) is essential as an HER catalyst, practical application in the HER has not been realized owing to the lack of any large-scale production of the 1T-TMDC and 1T/1T-TMDC heterostructure fabrication method. Here, polymorphic TMDC–TMDC heterostructures at a 4 in. wafer scale is reported for 1T-MoS2/1T-WS2 vertical heterostructures (1T/1T-MWH) or 2H-MoS2/2H-WS2 vertical heterostructures (2H/2H-MWH) under cold plasma conditions and process temperature. Simultaneous ion-bombardment onto substrates induces a few nanosized grain boundaries with discontinuous films, resulting in exposed edges that act as catalytically active sites. The electrocatalytic performances of the prepared polymorph (1T or 2H phases of MoS2 and WS2) and polymorphic heterostructures of 1T/1T-MWH and 2H/2H-MWH are compared. 1T/1T-MWH shows the highest electrocatalytic performance owing to its metallic 1T phase and heterostructures containing alloy structures at the heterointerface. Moreover, the nanosized grains of 1T/1T-MWH preserve their original phase after 1000 HER cycles, proving their robustness and durability.

Computational screening of layered metal chalcogenide materials for HER electrocatalysts, and its synergy with experiments

“…Noh et al [54] found MoS 2 C-edge on a WSe 2 support has ∆G H * = −0.008 eV at 1/4 ML. Seok et al [94] found 1T-MoS 2 /1T-WS 2 vertical heterostructures to perform well in HER. However, this particular heterostructure was not studied in [54].…”

Plasma Processing and Treatment of 2D Transition Metal Dichalcogenides: Tuning Properties and Defect Engineering

“…The presence of plasma can reduce impurities such as adventitious carbon, increase substrate affinity for interaction with gaseous precursors by surface activation, and result in a better uniformity and adhesion to substrate . In an atmospheric-pressure PECVD technique (Figure a as well as Figure a,b), MoS 2 and WS 2 multilayers as well as their heterostructures can directly be grown onto various substrates such as polyethylene terephthalate (PET) and Si at temperatures below 200 °C. − At an operational temperature of 150 °C, it is possible to directly synthesize 1T-MoS 2 and 1T-WS 2 thin films as well as their heterostructures that cannot be attained via conventional CVD methods. − …”

Development of polyoxometalate-based Ag-H2biim inorganic–organic hybrid compounds functionalized for the acid electrocatalytic hydrogen evolution reaction

“…In the past few years, advanced research has been conducted for the exploitation of Earth-abundant and efficient electrocatalysts toward the HER; for instance, transition metal sulfides and carbides, e.g., MoS 2 , WS 2 and Mo 2 C have shown excellent performance due to their similar electronic structures to that of Pt. [5][6][7][8][9][10][11][12] Polyoxometalates (POMs) are a class of metal oxide cluster compounds constituted of pre-transition metals (V, Mo, W, Nb, etc. ), which have been widely used in the fields of catalysis, energy and medicine.…”

“…, MoS 2 , WS 2 and Mo 2 C have shown excellent performance due to their similar electronic structures to that of Pt. 5–12…”