Growth and Capacitive Performance of Metals Engineered Tungsten Oxide Structures and Application in Colorant Sensors
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MRS Advances © 2018 Materials Research Society DOI: 10.1557/adv.2018.279
Growth and Capacitive Performance of Metals Engineered Tungsten Oxide Structures and Application in Colorant Sensors Pankaj Kumar1, Prashant K Sarswat1, and Michael L. Free1 1
Department of Metallurgical Engineering, University of Utah, Salt lake City, Utah 84112, USA
ABSTRACT
Tungsten oxide based micro and nanostructures as well as their 2-D integrated counterparts with appropriate surface modifications such as sensitization, coating of other semiconductors or growth of functional groups have been examined to enhance supercapacitance and sensing capabilities. With the goal of investigation of these changes, the electrochemical capacitance behavior of newly prepared nano and micro-structured tungsten oxide coated substrates were examined. The utilization of WO3 based sensors to differentiate edible colorant and toxic pigments, was also explored. The systematic electrochemical analysis and comparative study of selected colorants was done in order to establish a roadmap to detect model organic compounds for better preventive action.
INTRODUCTION Supercapacitors (SCs) have emerged as a promising energy source for the various energy related devices due to high energy density. The specific capacitance and charge/discharge behavior of the electrode governs the energy and electric performance of a supercapacitor. Although capacitance is a materials intrinsic property, one way of enhancement can be achieved by enhancing the surface area of the material. For example, tungsten oxide (WOx) in bulk form does not exhibit supercapacitance behavior but increased surface area in nanostructured WO x indicates a very high potential for supercapacitance applications. With the advent of nanotechnology, the nanostructure semiconductor metal oxides have attracted significant attention in supercapacitor applications [1]. In the same line of investigation, study indicates that ruthenium (Ru) oxide could attain a capacitance as high as 1500 Fg-1 [2]. However, due to the cost and environment issues, the Ru oxide utility in supercapacitors is not pursued widely. Consequently, alternative affordable transition metal oxides were investigated. The oxides of manganese (Mn), iron (Fe), tin (Sn), tungsten (W), nickel (Ni), and titanium (Ti) were considered for the capacitor applications. Due to excellent electrical conductivity, high intrinsic density, high cycling rate and multifunctional properties, WO x received considerable attention among all the metal oxides recently. In literature, depending on the processing, the specific capacitance of WOx varied from 30 Fg-1 to 797 Fg-1 [3]. It can be deduced from the literature data that the structure and morphology of WO x has a significant effect on the supercapacitance of WOx. In one study, WOx in the form of fused particles shows specific capacitance
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