Enhanced Hydrogen Evolution Catalysis from Chemically Exfoliated Metallic MoS₂ Nanosheets

Abstract

Promising catalytic activity from molybdenum disulfide (MoS2) in the hydrogen evolution reaction (HER) is attributed to active sites located along the edges of its two-dimensional layered crystal structure, but its performance is currently limited by the density and reactivity of active sites, poor electrical transport, and inefficient electrical contact to the catalyst. Here we report dramatically enhanced HER catalysis (an electrocatalytic current density of 10 mA/cm(2) at a low overpotential of -187 mV vs RHE and a Tafel slope of 43 mV/decade) from metallic nanosheets of 1T-MoS2 chemically exfoliated via lithium intercalation from semiconducting 2H-MoS2 nanostructures grown directly on graphite. Structural characterization and electrochemical studies confirmed that the nanosheets of the metallic MoS2 polymorph exhibit facile electrode kinetics and low-loss electrical transport and possess a proliferated density of catalytic active sites. These distinct and previously unexploited features of 1T-MoS2 make these metallic nanosheets a highly competitive earth-abundant HER catalyst.

Nickel Hydr(oxy)oxide Nanoparticles on Metallic MoS2 Nanosheets: A Synergistic Electrocatalyst for Hydrogen Evolution Reaction

“…The 2H‐MoS 2 was prepared by a hydrothermal method according to a reported literature,55 and it exhibits similar morphology as 1T‐MoS 2 but characteristic 2H phase (Figure S19, Supporting Information) 44, 55. 2H‐MoS 2 /Ni 2+ δ O δ (OH) 2− δ (1:1) hybrid was synthesized by just replacing 1T‐MoS 2 with 2H‐MoS 2 in the hybrid preparation.…”

“…Extensive efforts have been made to improve the HER activities of MoS 2 ‐based catalysts in acidic media by strategies such as nanostructure engineering,35, 36, 37, 38 defect engineering,39, 40, 41, 42, 43 phase engineering,44, 45, 46, 47, 48 and heteroatom doping49, 50, 51 to increase the number or enhance the intrinsic activity of active sites. However, little work has been reported to improve the HER activities of MoS 2 ‐based materials in alkaline media 31, 52.…”

Face the Edges: Catalytic Active Sites of Nanomaterials

“…This 1T‐MoS 2 can dramatically decrease the Tafel slope comparing with 2H‐MoS 2 in the same acidic environment ( Figure 2 f) 18. However, the best way to optimizing activity is not keeping on exploring 1T‐MoS 2 or some other unstable structures,44 but on other practical methods to maintain high stability while keeping accessible activity.…”

“…Another hot topic of heterogeneous catalysts is using NPs to serve as highly active catalysts 15. Academic researches of heterogeneous catalysis aim to realize undeveloped reactions16, 17 or optimize the activities of developing reactions 18, 19, 20. The boundary between homogeneous or heterogeneous is the size of catalyst.…”

Anchoring CoO Domains on CoSe2 Nanobelts as Bifunctional Electrocatalysts for Overall Water Splitting in Neutral Media

“…Metallic electrocatalysts have sparked great interest owing to their good conductivity and thus remarkable electroactivity 14. Although cobalt chalcogenides, typically metallic CoSe 2 ,15 show extraordinary achievement on catalyzing HER or OER, the low electrochemical performance of pure CoSe 2 remains to be further improved.…”