Fabrication of nanoporous tungsten oxide by galvanostatic anodization

Mukherjee, Niloy; Paulose, Maggie; Varghese, Oomman K.; Mor, Gopal K.; Grimes, Craig A.

doi:10.1557/jmr.2003.0321

Cited by 121 publications

(91 citation statements)

References 21 publications

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“…The use of this electrolyte is a key factor for the growth of ordered WO 3 nanochannels as it provides an ideal equilibrium between field-assisted passivation of W metal and oxide dissolution [38,[43][44][45], thus establishing the adequate electrochemical conditions for the growth of defined nanostructures. While rapid oxide dissolution that limits the growth of the anodic structure is reported to take place in most common electrolytes [46][47][48], (nominally) pure hot o-H 3 PO 4 provides an environment with limited water content and with phosphate ions that protect anodic tungsten oxide layer from rapid dissolution [42].…”

Section: Resultsmentioning

confidence: 99%

On the Supercapacitive Behaviour of Anodic Porous WO3-Based Negative Electrodes

Upadhyay

Altomare

Eugénio

et al. 2017

Electrochimica Acta

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Keywords: electrochemical anodization WO 3 nanostructure phosphoric acid supercapacitor energy storage A B S T R A C T Herein we illustrate the functionality as pseudocapacitive material of tungsten trioxide (WO 3 ) nanochannel layers fabricated by electrochemical anodization of W metal in pure hot ortho-phosphoric acid (o-H 3 PO 4 ). These layers are characterized by a defined nanochannel morphology and show remarkable pseudocapacitive behaviour in the negative potential (À0.8-0.5 V) in neutral aqueous electrolyte (1 M Na 2 SO 4 ). The maximum volumetric capacitance of 397 F cm À3 is obtained at 2 A cm À3. The WO 3 nanochannel layers display full capacitance retention (up to 114%) after 3500 charge-discharge cycles performed at 10 A cm À3 . The relatively high capacitance and retention ability are attributed to the high surface area provided by the regular and defined nanochannel morphology. Kinetic analysis of the electrochemical results for the best performing WO 3 structures, i.e., grown by 2 h-long anodization, reveals the occurrence of pseudocapacitance and diffusional controlled processes. Electrochemical impedance spectroscopy measurements show for the same structures a relatively low electrical resistance, which is the plausible cause for the superior electrochemical behaviour compared to the other structures.

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Section: Resultsmentioning

confidence: 99%

On the Supercapacitive Behaviour of Anodic Porous WO3-Based Negative Electrodes

Upadhyay

Altomare

Eugénio

et al. 2017

Electrochimica Acta

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“…Some of the earliest research into the fabrication of nanoporous WO 3 utilized a galvanostatic or constant current anodization process [66]. This study utilized a constant potential anodization where the potential across the electrochemical cell was energized to the desired voltage and held constant for the desired duration.…”

Section: Anodizing Voltage and Durationmentioning

confidence: 99%

Characterization of Micron-Scale Nanotublar Super Dielectric Materials

Gandy¹

2015

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Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instruction, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden, to ABSTRACT (maximum 200 words)This research is part of an ongoing program of study focused on dielectric materials based on a novel hypothesis: that porous electrically insulating solids in which the pores are filled with liquids containing an ionic species (such as water with dissolved salt) will have very high dielectric values by virtue of the separation of ions in the liquid phase and concurrent formation of large dipoles. Earlier work focused on the creation of super dielectric materials by saturating porous electrically insulating powders, such as alumina, with salt solutions.The focus of the present work is the characterization and evaluation of capacitors based on a novel dielectric: titanium dioxide nanotube arrays created by anodization and filled with a concentrated aqueous salt solution. Capacitors made up of this so-called nanotubular super dielectric material were found to have extreme dielectric constants, greater than one billion. The same capacitors also registered unprecedented energy densities, consistently greater than 400 joules per cubic centimeter, which is more than ten times the best commercial supercapacitors. Sufficient data was collected to propose a correlation relating dielectric thickness, salt concentration, and electrode surface area to overall energy density. Submitted in partial fulfillment of the requirements for the degree of SUBJECT TERMS MECHANICAL ENGINEER AND MASTER OF SCIENCE IN MECHANICAL ENGINEERING

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“…14, No. 3,2011 열증착법 (thermal evaporation), 12,13) 졸-젤 코팅 (sol-gel coating), 14,15) 양극산화 (anodization) [16][17][18][19][20][21] (Fig. 1(b, f)), 빛을 조사하며 제조한 산화물 (Fig.…”

Section: 서 론mentioning

confidence: 99%

The Effects of Pre-Annealing on Electrochemical Preparation for Nanoporous Tungsten Oxide Films

Kim¹,

Kim²,

Choi³

2011

Journal of the Korean Electrochemical Society

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: We describe that the surface and thickness of nanoporous WO 3 fabricated by both light-induced and light-absent anodization are affected by pre-annealing process from 200 o C to 600 o C. As a result, the nanoporous WO 3 with a thickness of 1.83 µm can be achieved by anodization for 6 hours after pre-annealing at 400 o C without illumination of light. Moreover, the thickness of nanoporous WO 3 fabricated by pre-annealing is thicker than that of WO 3 prepared by non-annealing process. However, the light illumination during anodization leads to convert the crystalline structure obtained by pre-annealing, which interfere the growth of nanoporous WO 3 . In this paper, we discuss about the growth mechanism of these different nanoporous WO 3 films.

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Fabrication of nanoporous tungsten oxide by galvanostatic anodization

Cited by 121 publications

References 21 publications

On the Supercapacitive Behaviour of Anodic Porous WO3-Based Negative Electrodes

On the Supercapacitive Behaviour of Anodic Porous WO3-Based Negative Electrodes

Characterization of Micron-Scale Nanotublar Super Dielectric Materials

The Effects of Pre-Annealing on Electrochemical Preparation for Nanoporous Tungsten Oxide Films

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