Hybrid nanostructures combining graphene–MoS<sub>2</sub> quantum dots for gas sensing

Niu, Yue; Jiao, Weicheng; Wang, Rongguo; Ding, Guomin; Huang, Yarong

doi:10.1039/c6ta03267b

Cited by 81 publications

(42 citation statements)

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“…This indicates the exfoliation along the c-axis of the MoSe 2 flakes, which occurs without any phase changes. [113,154,155] The data also exclude the presence of Se powder and which is in agreement with literature reports on MoS 2 and MoSe 2 . [156][157][158][159][160] The additional peaks at binding energies of 232.5±0.2 eV and 235.7±0.2 eV are assigned to the Mo(VI) state and are related to MoO 3 residue.…”

Section: Production Processing and Characterization Of Swcnts Graphsupporting

confidence: 91%

Engineered MoSe₂‐Based Heterostructures for Efficient Electrochemical Hydrogen Evolution Reaction

Najafi

Bellani

Oropesa‐Nuñez

et al. 2018

Advanced Energy Materials

177

143

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Two-dimensional transition metal-dichalcogenides are emerging as efficient and costeffective electrocatalysts for hydrogen evolution reaction (HER). However, only the edge sites of their trigonal prismatic phase show HER-electrocatalytic properties, while the basal plane, which is absent of defective/unsaturated sites, is inactive. Here, we tackle the key challenge that is increasing the number of electrocatalytic sites by designing and engineering heterostructures composed of single-/few-layer MoSe 2 flakes and carbon nanomaterials (graphene or single-wall carbon nanotubes (SWNTs)) produced by solution processing. The electrochemical coupling between the materials that comprise the heterostructure effectively enhances the HER-electrocatalytic activity of the native MoSe 2 flakes. The optimization of the mass loading of MoSe 2 flakes and their electrode assembly via monolithic heterostructure stacking provided a cathodic current density of 10mAcm -2 at overpotential of 100mV, a Tafel slope of 63mVdec -1 and an exchange current density (j 0 ) of 0.203µAcm -2 . In addition, electrode thermal annealing in a hydrogen environment and chemical bathing in nbutyllithium are exploited to texturize the basal planes of the MoSe 2 flakes (through Sevacancies creation) and to achieve in situ semiconducting-to-metallic phase conversion, respectively, thus they activate new HER-electrocatalytic sites. The as-engineered electrodes show a 4.8-fold enhancement of j 0 and a decrease in the Tafel slope to 54mVdec -1 .

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Section: Production Processing and Characterization Of Swcnts Graphsupporting

confidence: 91%

Engineered MoSe₂‐Based Heterostructures for Efficient Electrochemical Hydrogen Evolution Reaction

Najafi

Bellani

Oropesa‐Nuñez

et al. 2018

Advanced Energy Materials

177

143

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“…This indicates that the NbS 2 akes are arranged parallel to the c-axis perpendicular to the substrate and retain their native crystal structure. 48,101 Raman spectroscopy analysis ( Fig. 1l) further conrms the crystallinity of the exfoliated samples, well displaying the nondegenerate Raman active modes of the native crystals predicted by group theory for 2H-NbS 2 (space group: D 4 6h ) 102,103 and 3R-NbS 2 (space group: C 5 3v ).…”

Section: Synthesis and Exfoliation Of Nbs 2 Crystalsmentioning

confidence: 58%

Niobium disulphide (NbS₂)-based (heterogeneous) electrocatalysts for an efficient hydrogen evolution reaction

et al. 2019

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The design of efficient and cost-effective catalysts for the hydrogen evolution reaction (HER) is the key for molecular hydrogen (H 2 ) production from electrochemical water splitting. Transition metal dichalcogenides (MX 2 ), most notably group-6 MX 2 (e.g., MoS 2 and WS 2 ), are appealing catalysts for the HER alternative to the best, but highly expensive, Pt-group elements. However, their HER activity is typically restricted to their edge sites rather than their basal plane. Furthermore, their semiconducting properties hinder an efficient electron transfer to the catalytic sites, which impedes a high rate of H 2 production. Herein, we exploit liquid-phase exfoliation-produced metallic (1H, 2H and 3R) NbS 2 nanoflakes, belonging to the class of metallic layered group-5 MX 2 , to overcome the abovementioned limitations. Both chemical treatment with hygroscopic Li salt and electrochemical in operando self-nanostructuring are exploited to improve the NbS 2 nanoflake HER activity. The combination of NbS 2 with other MX 2 , in our case MoSe 2 , also provides heterogeneous catalysts accelerating the HER kinetics of the individual counterparts. The designed NbS 2 -based catalysts exhibit an overpotential at a cathodic current of 10 mA cm À2 (h 10 ) as low as 0.10 and 0.22 V vs. RHE in 0.5 M H 2 SO 4 and 1 M KOH, respectively. In 0.5 M H 2 SO 4 , the HER activity of the NbS 2 -based catalysts is also superior to those of the Pt/C benchmark at current densities higher than 80 mA cm À2 . Our work provides general guidelines for a scalable and cost-effective exploitation of NbS 2 , as well as the entire MX 2 portfolio, for attaining a viable H 2 production through electrochemical routes.

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“…26 Interactions between graphene and electronegative moieties as well as electron donating and electron withdrawing molecular entities have been studied extensively. 29 All these recent developments aptly demonstrate that both bulk graphene as well as its size-quantized variants could be utilized to design efficient gas-sensors. 29 All these recent developments aptly demonstrate that both bulk graphene as well as its size-quantized variants could be utilized to design efficient gas-sensors.…”

Section: Introductionmentioning

confidence: 99%

Optical response and gas sequestration properties of metal cluster supported graphene nanoflakes

Chakraborty

Chattaraj

2016

Phys. Chem. Chem. Phys.

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The possibility of obtaining metal cluster (M3O(+), M = Li, Na, K) supported pristine, B-doped and BN-doped graphene nanoflakes (GR, BGR and BNGR, respectively) has been investigated by carrying out density functional theory (DFT) based calculations. Thermochemical analysis reveals the good stability of M3O(+)@GR/BGR/BNGR moieties. The dynamic stability of M3O(+)@GR/BGR/BNGR moieties is confirmed through an atom-centered density matrix propagation simulation at 298 K up to 500 fs. Orbital and electrostatic interactions play pivotal roles in stabilizing the metal-cluster supported graphene nanoflakes. The metal clusters lower the Fermi levels of the host nanoflakes and enable them to exhibit reasonably good optical response properties such as polarizability and static first hyperpolarizability. In particular, Na3O(+)/K3O(+)@BGR complexes exhibit very large first hyperpolarizability values at the static field limit. All the M3O(+)@BGR/BNGR moieties demonstrate broadband optical absorption encompassing the ultraviolet, visible as well as infrared domains. The metal-cluster supported graphene nanoflakes, in general, can sequestrate polar molecules, viz. CO, NO and CH3OH, in a thermodynamically more favorable way than GR, BGR and BNGR. In the adsorbed state, the CO, NO and CH3OH molecules, in general, attain an 'active' state as compared to their free counterparts.

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Hybrid nanostructures combining graphene–MoS₂ quantum dots for gas sensing

Abstract: In this work, we report a facile technique for the synthesis of graphene/MoS2 quantum dots hybrid nanostructures for gas sensing.

Cited by 81 publications

References 50 publications

Engineered MoSe₂‐Based Heterostructures for Efficient Electrochemical Hydrogen Evolution Reaction

Engineered MoSe₂‐Based Heterostructures for Efficient Electrochemical Hydrogen Evolution Reaction

Niobium disulphide (NbS₂)-based (heterogeneous) electrocatalysts for an efficient hydrogen evolution reaction

Optical response and gas sequestration properties of metal cluster supported graphene nanoflakes

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Hybrid nanostructures combining graphene–MoS2 quantum dots for gas sensing

Abstract: In this work, we report a facile technique for the synthesis of graphene/MoS2 quantum dots hybrid nanostructures for gas sensing.

Cited by 81 publications

References 50 publications

Engineered MoSe2‐Based Heterostructures for Efficient Electrochemical Hydrogen Evolution Reaction

Engineered MoSe2‐Based Heterostructures for Efficient Electrochemical Hydrogen Evolution Reaction

Niobium disulphide (NbS2)-based (heterogeneous) electrocatalysts for an efficient hydrogen evolution reaction

Optical response and gas sequestration properties of metal cluster supported graphene nanoflakes

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Product

Resources

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Hybrid nanostructures combining graphene–MoS₂ quantum dots for gas sensing

Engineered MoSe₂‐Based Heterostructures for Efficient Electrochemical Hydrogen Evolution Reaction

Engineered MoSe₂‐Based Heterostructures for Efficient Electrochemical Hydrogen Evolution Reaction

Niobium disulphide (NbS₂)-based (heterogeneous) electrocatalysts for an efficient hydrogen evolution reaction