Hydrogen on hybrid MoS₂/graphene nanostructures

Abstract

Transition metal dichalcogenides are rising candidates for the replacement of Pt catalysts in water splitting. In this theoretical study we focus on the hydrogen evolution reaction part of this process and on how hydrogen (H) interacts with MoS2 nanostructures, free‐standing or positioned on a graphene substrate. Density functional theory calculations confirm the stability of such nanostructures and our results for H on several configurations, from 2D infinite monolayers to quasi‐1D MoS2 ribbons and quasi‐0D MoS2 flakes, are presented. We calculate the adsorption energy of H atoms on various sites of the MoS2 nanostructures, notably at Mo and S active edges. Comparing free‐standing and MoS2/graphene hybrid systems we find that the effect of the support on the adsorption of H on MoS2 nanostructures is quite significant when the substrate induces strain. (© 2016 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)

Adsorption on Metallic Edges of Transition Metal Dichalcogenides

“…For comparison with adsorption on the edges, we briefly summarize some of our results for the basal plane of monolayers, which are in overall agreement with literature, when available. [ 26,40,42,43 ]…”

“…For comparison with adsorption on the edges, we briefly summarize some of our results for the basal plane of monolayers, which are in overall agreement with literature, when available. [26,40,42,43] For atomic oxygen at full coverage, i.e., one O atom per X atom on one side of the MX 2 monolayer, we find that the adsorption energies for MoS 2 , WS 2 , MoSe 2 , WSe 2 are À0.27, À0.08, 0.81, 0.89 eV, respectively, showing that sulfides, unlike selenides, may be fully oxidized with O atoms adsorbed on top of S atoms.…”

“…[ 21,22 ] In the search for inexpensive catalysts in technologically important chemical reactions, and other TMD nanostructures have emerged as prime candidates, e.g., in desulfurization process, or to replace platinum in fuel cells, oxygen reduction, water splitting and hydrogen evolution reaction (HER). [ 23–26 ] TMD metallic edge states are active in HER, adsorbing hydrogen neither too weakly nor too strongly. Efforts to activate basal planes in electrocatalysis and photocatalysis include defects, doping and hybridization with other nanomaterials.…”

Spin-resolved transport properties in molybdenum disulfide superlattice

“…Pan et al used the ultra-short gate lengths for ML-MoS 2 transistors to fabricate high-performance the short-gate MoS 2 transistors with high efficiency by conventional Si-based field-effect transistor with 0.7 nm monolayer CVD MoS 2 [26]. Since ML-MoS 2 has a strong SOC, one can combine graphene (with a weak SOC) and MoS 2 (with strong SOC) in a van der Waals heterostructure to obtain a controllable electric gate of the spin current and spin lifetime to obtain a high SOC material [27][28][29][30]. Niu investigates the valley-resolved thermoelectric transport through a magnetic silicene superlattice and demonstrates a strong valley polarization [31].…”

Stability of metallic edges and Fermi-level pinning in transition-metal dichalcogenide nanoribbons

“…Kim et al [20] found that armchair nanoribbons can be stabilized by H adsorption and possess a semiconducting character with strong exciton effects. Finally, Mos 2 nanoribbons could have a key role in the hydrogen evolution reaction [21,22], and graphene support enhances these features [23,24]. Yu et al [25] verified the tunability of edge states using electric field and hydrogen absorption.…”