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We studied using organic liquids (cyclohexane, n-butanol, and ethylene glycol) to modulate the transport properties at room temperature of an epitaxial VO2 film on a VO2/Al2O3 heterostructure. The resistance of the VO2 film increased when coated with cyclohexane or n-butanol, with maximum changes of 31% and 3.8%, respectively. In contrast, it decreased when coated with ethylene glycol, with a maximum change of −7.7%. In all cases, the resistance recovered to its original value after removing the organic liquid. This organic-liquid-induced reversible resistance switching suggests that VO2 films can be used as organic molecular sensors.

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“…5(a). 37,38 In contrast, when ethylene glycol coats the film, the V 4+ ions lose electrons and oxidize into V 5+ ions.…”

Section: Resultsmentioning

confidence: 99%

“…38,[44][45][46] Figs. 5(c)-5(e) show the Lorentzian-Gaussian fits of V 2p peaks for the VO 2 film without polar liquids, with cyclohexane, and with ethylene glycol, respectively.…”

Section: Resultsmentioning

confidence: 99%

Resistance switching of epitaxial VO2/Al2O3 heterostructure at room temperature induced by organic liquids

et al. 2015

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“…The energy region between 514 eV and 527 eV belongs to the V 2p state. The spin-orbit coupling splits the V 2p states into j = 3/2 and j = 1/2 by about 7 eV [11], which centered at 517 eV and 524 eV, respectively. A careful fitness of the V 2p 3/2 peak showed that it contained two contributions, which centered at 516.1 eV and 517.5 eV, respectively.…”

Section: Structural and Physical Propertiesmentioning

confidence: 99%

Synthesis and characterizations of highly crystallized α′-NaV2O5 needles prepared by a hydrothermal process

Ming

Chen

et al. 2009

Journal of Alloys and Compounds

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“…Figure 2a and 2b illustrate the difference between the V 2p region for an as-grown V 2 O 5 film and one discharged to 2.8V vs Li/Li + . We fit the V 4+ component using a constrained doublet, based on the intrinsic multiplet splitting exhibited by the V 4+ ion as previously shown by first principles calculations 16 and experiment 17 (Supplementary Section 1). The j = 1/2 peak exhibits exceptional broadening due to a very fast Coster-Kronig relaxation process 14 , and so we use only the j=3/2 peak for analysis.…”

Section: Quantifying the State Of Charge In V 2 O 5 With Xpsmentioning

confidence: 99%

The reaction current distribution in battery electrode materials revealed by XPS-based state-of-charge mapping

Pearse

Gillette

Lee

et al. 2016

Phys. Chem. Chem. Phys.

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Morphologically complex electrochemical systems such as composite or nanostructured lithium ion battery electrodes exhibit spatially inhomogeneous internal current distributions, particularly when driven at high total currents, due to resistances in the electrodes and electrolyte, distributions of diffusion path lengths, and nonlinear current-voltage characteristics. Measuring and controlling these distributions is interesting from both an engineering standpoint, as nonhomogenous currents lead to lower utilization of electrode material, as well as from a fundamental standpoint, as comparisons between theory and experiment are relatively scarce. Here we describe a new approach using a deliberately simple model battery electrode to examine the current distribution in a electrode material limited by poor electronic conductivity. We utilize quantitative spatially resolved X-ray photoelectron spectroscopy to measure the spatial distribution of the state-of-charge of a V2O5 model electrode as a proxy measure for the current distribution on electrodes discharged at varying current densities. We show that the current at the electrode-electrolyte interface falls off with distance from the current collector, and that the current distribution is a strong function of total current. We compare the observed distributions with a simple analytical model which reproduces the dependence of the distribution on total current, but fails to predict the correct length scale. A more complete numerical simulation suggests that dynamic changes in the electronic conductivity of the V2O5 concurrent with lithium insertion may contribute to the differences between theory and experiment. Our observations should help inform design criteria for future electrode architectures.

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X-ray photoelectron spectroscopy study of mixed-valence effects and charge fluctuation inNaxV2O5

Cited by 14 publications

References 20 publications

Resistance switching of epitaxial VO2/Al2O3 heterostructure at room temperature induced by organic liquids

Resistance switching of epitaxial VO2/Al2O3 heterostructure at room temperature induced by organic liquids

Synthesis and characterizations of highly crystallized α′-NaV2O5 needles prepared by a hydrothermal process

The reaction current distribution in battery electrode materials revealed by XPS-based state-of-charge mapping

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