School Of Basic And Applied Sciences

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Author: search.filters.author.Ma, Y.-R.

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    Promising field electron emission performance of vertically aligned one dimensional (1D) brookite (?) TiO2 nanorods
    (Royal Society of Chemistry, 2016) Devan, R.S.; Ma, Y.-R.; More, M.A.; Khare, R.T.; Antad, V.V.; Patil, R.A.; Thakare, V.P.; Dhayal, R.S.; Schmidt-Mende, L.
    We evidence field-electron emission (FE) studies on the large-area array of one-dimensional (1D) brookite (?) TiO2 nanorods. The pure 1D ?-TiO2 nanorods of 10 nm width and 760 nm long were synthesized on Si substrate utilizing hot-filament metal vapor deposition technique. X-ray diffraction (XRD) and transmission electron microscopy (TEM) analysis evidenced the ?-TiO2 nanorods to be composed of orthorhombic crystals in brookite (?) phase. X-ray photoemission spectroscopy (XPS) revealed the formation of pure stoichiometric (i.e. 1 : 1.98) 1D TiO2 nanorods. The values of turn-on field, required to draw current density of 10 ?A cm-2, was observed 3.9 V ?m-1 for pristine 1D ?-TiO2 nanorods emitters, which were found significantly lower than doped/undoped 1D TiO2 nanostructures (i.e. nanotubes, nanowires, nanorods) based field emitters. The enhanced FE behavior of the TiO2/Si emitter can be attributed to modulation of electronic properties due to the high aspect ratio of vertically aligned TiO2 nanorods. Furthermore, the orthodox emission situation of pristine TiO2/Si emitters exhibit good emission stability and reveal their potentials as promising FE material. ? 2016 The Royal Society of Chemistry.
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    Nano-Heteroarchitectures of Two-Dimensional MoS2@ One-Dimensional Brookite TiO2 Nanorods: Prominent Electron Emitters for Displays
    (American Chemical Society, 2017) Devan, R.S.; Thakare, V.P.; Antad, V.V.; Chikate, P.R.; Khare, R.T.; More, M.A.; Dhayal, R.S.; Patil, S.I.; Ma, Y.-R.; Schmidt-Mende, L.
    We report comparative field electron emission (FE) studies on a large-area array of two-dimensional MoS2-coated one-dimensional (1D) brookite (?) TiO2 nanorods synthesized on Si substrate utilizing hot-filament metal vapor deposition technique and pulsed laser deposition method, independently. The 10 nm wide and 760 nm long 1D ?-TiO2 nanorods were coated with MoS2 layers of thickness 4 (?2), 20 (?3), and 40 (?3) nm. The turn-on field (Eon) of 2.5 V/?m required to a draw current density of 10 ?A/cm2 observed for MoS2-coated 1D ?-TiO2 nanorods emitters is significantly lower than that of doped/undoped 1D TiO2 nanostructures, pristine MoS2 sheets, MoS2@SnO2, and TiO2@MoS2 heterostructure-based field emitters. The orthodoxy test confirms the viability of the field emission measurements, specifically field enhancement factor (?FE) of the MoS2@TiO2/Si emitters. The enhanced FE behavior of the MoS2@TiO2/Si emitter can be attributed to the modulation of the electronic properties due to heterostructure and interface effects, in addition to the high aspect ratio of the vertically aligned TiO2 nanorods. Furthermore, these MoS2@TiO2/Si emitters exhibit better emission stability. The results obtained herein suggest that the heteroarchitecture of MoS2@?-TiO2 nanorods holds the potential for their applications in FE-based nanoelectronic devices such as displays and electron sources. Moreover, the strategy employed here to enhance the FE behavior via rational design of heteroarchitecture structure can be further extended to improve other functionalities of various nanomaterials. ? 2017 American Chemical Society.
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    Highly stable supercapacitive performance of one-dimensional (1D) brookite TiO2 nanoneedles
    (Royal Society of Chemistry, 2016) Devan, R.S.; Ma, Y.-R.; Patil, R.A.; Lukas, S.-M.
    We report the highly stable supercapacitive performance of one-dimensional (1D) nanoneedles of brookite (?) TiO2 synthesized on a conducting glass substrate. The 1D ?-TiO2 nanoneedles synthesized over a large area array utilizing hot-filament metal vapor deposition (HFMVD) were ?24-26 nm wide, ?650 nm long and tapered in a downward direction. X-ray photoemission spectroscopy (XPS) revealed their chemical properties and stoichiometric Ti and O composition. The 1D ?-TiO2 nanoneedles execute as parallel units for charge storage, yielding a specific capacitance of 34.1 mF g-1. Electrochemical impedance spectroscopy revealed that the large surface area and brookite crystalline nature of the 1D nanoneedles provided easy access to Na+ ions, and resulted in low diffusion resistance, playing a key role in their stable charging-discharging electrochemical mechanism. Moreover, the non-faradic mechanism of these nanoneedles delivered better durability and high stability up to 10000 cycles, and a columbic efficiency of 98%. Therefore, 1D ?-TiO2 nanoneedles hold potential as an electrode material for highly stable supercapacitive performance with long cycle lifetime. ? 2016 The Royal Society of Chemistry.