Tunable Plasmon Resonances in Two‐Dimensional Molybdenum Oxide Nanoflakes

Abstract

appreciable free carrier concentration. [5][6][7] The same strategy can potentially be implemented in selected 2D semiconductors. Another concern is the damping losses that should be kept low for applications such as optical communications, in which a long propagation of waves is necessary. [ 7 ] Reducing such damping losses requires that the product of the effective electron mass and the free charge mobility must be large in the 2D material. As a result, fi nding favorable materials that satisfy the aforementioned conditions are necessary for advancing the fi eld of 2D plasmonics.The creation of stable 2D semiconducting oxides of tungsten and molybdenum is possible, as we demonstrated previously. [ 8,9 ] In a recent topical feature article, Gregorieva and Geim have separated out these oxides as a unique group of 2D materials and predicted their signifi cant role in the future of planar structures. [ 10 ] The impact of these two metal oxides can be extended into the plasmonic realm, and, in fact, plasmon resonances in the one-dimensional (1D) morphologies of these two oxides have recently been demonstrated. Manthiram and Alivisatos reported plasmon resonances in 1D sub-stoichiometric semiconducting tungsten oxide, [ 6 ] while Huang et al. have shown the generation of plasmon resonances in 1D tubular reduced molybdenum oxide suspensions. [ 5 ] Advantageously both tungsten and molybdenum oxides can be ultra-doped and have also large dielectric constants, which both are important factors for obtaining plasmon resonances in the near IR and visible regions. [ 2 ] In 1D sub-stoichiometric tungsten and molybdenum oxides, the plasmon resonances are a function of two modest depolarization factors along the cross section of the 1D structure ( Figure 1 a -Supporting Information, Section S1 for the equations). However, the existence of one large depolarization factor reduces the wavelength of the plasmon resonances in 2D structures of similar stoichiometry.Accordingly, here, we explore tunable plasmonics in substoichiometric 2D molybdenum oxide nanofl akes in the visible range. The unique properties of 2D molybdenum oxide such as the possibility of high level ionic intercalation (hence ultradoping), large permittivity and the effect of the depolarization factor in 2D fl akes are used for demonstrating tunable plasmon resonance in this range. We investigate the effect of intercalating ions and changing the lateral dimensions of the fl akes on the plasmon resonance peaks of a reduced quasi-metallic form of molybdenum oxide.Molybdenum trioxide (MoO 3 ) is a stable n -type semiconductor under a wide range of conditions with a bandgap of ca. 3.2 eV, which is capable of adsorbing energy from a small portion of the visible light spectrum. [ 5,11 ] The most frequently 2D materials exhibit certain physical and chemical properties that are fundamentally different from their bulk counterparts. [ 1,2 ] The electronic and optical properties seen in the selected 2D materials may lead to signifi cantly altered plasmon dispersion relationsh...

Turbulence-assisted shear exfoliation of graphene using household detergent and a kitchen blender

“…Finally, we note that while we focus on the production of graphene using this method, it can easily be extended to exfoliate inorganic layered compounds such as BN, MoS 2 or MoO 3 . 32,[43][44][45] It is important to note that the value of this work is not the demonstration that kitchen blenders can be used to produce graphene, although this may be a useful result. Rather, this work shows that industrial rotating blade stirred tank reactors are a promising new technology for large scale graphene production.…”

Large-Scale Production of Size-Controlled MoS2 Nanosheets by Shear Exfoliation

“…8,23 Such dispersions can be used to process the nanosheets into functional structures such as films, networks and composites. 20,[24][25][26] Such structures have proven useful in a range of application areas including plasmonics, 27 photodetectors, 24,28,29 electrodes in dye-sensitised solar cells, 30 supercapacitors 31 and batteries 26,32 or electro-catalysts 33 for hydrogen evolution.…”

Application of 2D-MoO3 nano-flakes in organic light emitting diodes: effect of semiconductor to metal transition with irradiation

“…MoO 3 nano-akes have been used for hydrogen gas (H 2 ) sensing, photoluminescence and eld emission. [24][25][26] Recently, Alsaif et al 27 demonstrated tunable plasmon resonances from 2D MoO 3 nano-akes. These reports have shown the potential of MoO 3 nano-akes; however, their application in devices is required to further prove their potential.…”

“…The most successful methods are the modied hot plate method, 25 the plasma assisted paste sublimation process, 35 the organic solvent assisted grinding and sonication method, 26,27 etc. Here, we adapted the organic solvent-assisted grinding and sonication method of liquid exfoliation to bulk MoO 3 to obtain 2D nano-akes.…”

“…Here, we adapted the organic solvent-assisted grinding and sonication method of liquid exfoliation to bulk MoO 3 to obtain 2D nano-akes. Alsaif et al 27 observed that the controlled solar illumination of a 2D MoO 3 nano-ake suspension alters its properties drastically, according to characterizations by Raman, X-ray diffraction, and X-ray photoelectron spectroscopy (XPS). They observed that the solar illumination of these nano-akes decreases the semiconducting properties and induces metallic properties as the duration of exposure is increased.…”