Stacking sequence dependent photo-electrocatalytic performance of CVD grown MoS₂/graphene van der Waals solids

Abstract

New layered solids by the combinatorial stacking of different atomic layers are emanating as novel candidates for energy efficient devices. Here, sequentially stacked single layer graphene-molybdenum disulfide (MoS) van der Waals (vdW) solids are demonstrated for their efficacy in the catalysis of hydrogen evolution reaction (HER), and importance of their stacking order in tuning the photo-electrocatalytic (PEC) efficiency is unraveled. Single layer graphene and a few layered MoS stacked vdW solids based transparent flexible electrodes were prepared, and a particular stacking sequence where top-graphene: bottom-MoS/polydimethylsiloxane (PDMS) geometry (MSGR) exhibited the lowest onset and over potentials and a very high exchange current density (j ∼ 245 ± 1 μA cm) in acidic HER in comparison to the individual layers and other stacked configuration (MoS on top of graphene on PDMS, GRMS). The HER studies under dark and white light illuminations were conducted to explore the PEC responses of the devices. The augmented HER performance of MSGR is further confirmed from the charge transfer resistance measurements using electrochemical impedance spectroscopy. Role of graphene plasmonics and MoS to graphene electron transfer were studied, and this study unravels the importance of a new factor, stacking order of vdW layers, while designing novel devices from the layered solids.

Molybdenum disulfide–graphene van der Waals heterostructures as stable and sensitive electrochemical sensing platforms

“…The vdWs' heterostructures from the individual layers were formed by (PMMA-assisted wet transfer method (Fig. 1a), as discussed in the experimental section [33]. The transferred materials are abbreviated as G (graphene), MS (MoS 2 ), and GMS (graphene-MoS 2 ) throughout the article.…”

“…Hence, such interfacing is found to be resulting in new solids of interesting electronic, optical, and electrochemical properties [30][31][32]. It is shown that even pristine graphene surfaces become electrochemically active while forming vdWs structures with MoS 2 and hBN [33,34]. Furthermore, vdWs structures of graphene with MoS 2 monolayers (MS) were found to provide enhanced hydrogen evolution catalytic activity compared with bare MS along with the enhanced stability even in harsh acid conditions and the interfacial charge transfer from graphene to MS was also established [35].…”

Strongly enhanced visible light photoelectrocatalytic hydrogen evolution reaction in an n-doped MoS2 /TiO2(B) heterojunction by selective decoration of platinum nanoparticles at the MoS2 edge sites

“…S7(c), ESI †) under dark and light conditions. 64 In the dark, the R ct is calculated to be lower for MSTB (102 U) as compared to those of the pristine TB (527 U) and MS (132 U). Interestingly, aer the Pt NP decoration, the R ct dramatically reduces to 36 U, 33 U and 27 U for PMS, PTB, and PMSTB, respectively, in the dark.…”

Chemical Mass Production of MoS2/Graphene van der Waals Heterostructure as a High‐Performance Li‐ion Intercalation Host

“…In addition, trapped in a cage of limited electronic conductivity, it is needed to assemble MoS 2 with conductive partners (such as graphene (GR)) to overcome this limitation . Various MoS 2 /GR composites have been developed recently (such as MoS 2 /GR hybrid, MoS 2 /N‐doped GR, and 3D MoS 2 /GR), while these composites are not well controlled in structure with the limited interface contact area between the dozens‐layered MoS 2 sheets and stacked GR sheets, failing to achieve the promising effects observed in single‐layered stacks …”

“…[9,10] Various MoS 2 /GR composites have been developed recently (such as MoS 2 /GR hybrid, [11] MoS 2 /N-doped GR, [12,13] and 3D MoS 2 /GR [14,15] ), while these composites are not well controlled in structure with the limited interface contact area between the dozens-layered MoS 2 sheets and stacked GR sheets, [16] failing to achieve the promising effects observed in single-layered stacks. [17,18] Very recently, 2D van der Waals (vdW) heterostructure assembled by stacking MoS 2 and GR layers in hetero-layered architectures (MoS 2 /GR heterostructure) is proposed as a promising electrode material for LIBs and other metal ion batteries. [19][20][21][22][23] In comparison with the reported MoS 2 /GR composites, the large accessible surface of GR can ensure high MoS 2 loading in MoS 2 /GR heterostructure while keeping MoS 2 effectively exposed, which is critical for electrochemical applications.…”