A study of thin anodic WO3 films by electrochemical impedance spectroscopy

Biaggio, Sonia R.; Rocha‐Filho, Romeu C.; Vilche, J. R.; Varela, F.E.; Gassa, Liliana Mabel

doi:10.1016/s0013-4686(96)00375-1

Cited by 58 publications

(31 citation statements)

References 28 publications

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“…This behaviour, which is similar to the one previously reported 14,15 for thin WO3 films anodically grown on tungsten in several electrolytes, can be partially due to a higher contribution from the surface states on decreasing the film thickness. However, an influence of the thickness on the ND value as a consequence of a higher defect concentration in thin films cannot be excluded.…”

Section: Electrochemical Impedance Datasupporting

confidence: 90%

“…As pointed out previously 15 , this happens because the faradaic reaction decreases sharply for fields lower than the film formation field. Thus, from impedance spectra obtained at E < Ef , the values of C decrease with increasing E (see Fig.…”

Section: Electrochemical Impedance Datamentioning

confidence: 52%

“…However, impedance data are diagnostically useful, as they can provide a variety of information, in particular on the main reactions contributing to the faradaic current at the reacting interface and on the electrical characteristics of the anodic films on the metal electrode [14][15][16][17][18] .…”

Section: Electrochemical Impedance Datamentioning

confidence: 99%

“…3. Then, the whole thin film is in deep depleted conditions, with surface charges at both the oxide/solution and the metal/oxide interfaces [13][14][15] , and Cox is the capacitance available. On the other hand, at the lower operational potentials, C can be assumed as corresponding to the space charge capacitance (Csc) of the semiconductor Nb2O5 film in the depleted region, after taking into account the value of CH (20 µF cm -2 ).…”

Section: Electrochemical Impedance Datamentioning

confidence: 99%

“…6, 615-620, 1997.high-voltage anodised niobium), there is no report in the literature of a systematic study of the impedance behaviour of thin films (< 20 nm). Recently we have investigated the electrical and semiconducting properties of thin anodic films of tungsten 14,15 , zirconium 16 and tin-indium alloys 17,18 . Herein we are extending these systematic investigations to niobium; thus, the main purpose of this work was to characterise the electrochemical behaviour and electrical properties of thin anodic passive films potentiostatically formed on niobium in aqueous 0.5 mol/L H3PO4 solutions, using electrochemical impedance spectroscopy.…”

Section: Introductionmentioning

confidence: 99%

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Electrochemical characterization of thin passive films on Nb electrodes in H3PO4 solutions

Biaggio¹,

Bocchi²,

Rocha‐Filho³

et al. 1997

J. Braz. Chem. Soc.

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The electrical and semiconducting properties of thin anodic passive films potentiostatically formed (1 V ≤ E f ≤ 5 V vs. sce) on polycrystalline niobium electrodes in aqueous 0.5 mol/L H3PO4 solutions (pH 1.3) were studied, at room temperature, using electrochemical impedance spectroscopy. The data were analysed with a transfer function using a non-linear fitting routine, assuming that the resistance of the film is coupled in series with the faradaic impedance of the Nb(0) → Nb(V) reaction, and these in parallel with the capacitance of the passive film/electrolyte interface. The relative permittivity of the films was estimated as about 44. The number concentration of donors (ND) in the films was found to decrease with E f (i.e., with increasing film thickness). A flat band potential value of -0.72 V was also obtained from Mott-Schottky plots.Utilizando-se a espectroscopia de impedância eletroquímica, foram estudadas as propriedades elétricas e semicondutoras de filmes anódicos passivos formados potenciostaticamente (1 V ≤ E f ≤ 5 V vs. ecs) sobre eletrodos de nióbio policristalino em soluções aquosas de H3PO4 0,5 mol/L (pH 1,3), a temperatura ambiente. Os dados foram analisados com uma função de transferência usando uma rotina de ajuste não-linear, supondo que a resistência do filme está acoplada em série com a impedância faradaica da reação Nb(0) → Nb(V) e estas em paralelo com a capacitância da interface filme/eletrólito. A permissividade relativa dos filmes foi estimada como cerca de 44. Encontrou-se que a concentração em número de doadores (ND) nos filmes decresce com E f (isto é, à medida que a espessura do filme aumenta). A partir de gráficos de Mott-Schottky, também obteve-se um valor de -0,72 V para o potencial de banda plana.

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Section: Electrochemical Impedance Datasupporting

confidence: 90%

Section: Electrochemical Impedance Datamentioning

confidence: 52%

Section: Electrochemical Impedance Datamentioning

confidence: 99%

Section: Electrochemical Impedance Datamentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Electrochemical characterization of thin passive films on Nb electrodes in H3PO4 solutions

Biaggio¹,

Bocchi²,

Rocha‐Filho³

et al. 1997

J. Braz. Chem. Soc.

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Photoanodes Based on Nanostructured WO₃ for Water Splitting

et al. 2012

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Anodically grown WO3 photoelectrodes prepared in an N-methylformamide (NMF) electrolyte have been investigated with the aim of exploring the effects induced by anodization time and water concentration in the electrochemical bath on the properties of the resulting photoanodes. An n-type WO3 semiconductor is one of the most promising photoanodes for hydrogen production from water splitting and the electrochemical anodization of tungsten allows very good photoelectrodes, which are characterized by a low charge-transfer resistance and an increased spectral response in the visible region, to be obtained. These photoanodes were investigated by a combination of steady state and transient photoelectrochemical techniques and a correlation between photocurrent produced, morphology, and charge transport has been evaluated

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Dynamic manipulation of modes in an optical waveguide using dielectrophoresis

et al. 2012

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The emergence of optofluidics has brought a high degree of tuneability and reconfigurability to optical devices. These possibilities are provided by characteristics of fluids including mobility, wide range of index modulation, and abrupt interfaces that can be easily reshaped. In this work, we created a new class of optofluidic waveguides, in which suspended mesoparticles were employed to greatly enhance the flexibility of the system. We demonstrated tuneable quasi single mode waveguides using spatially controllable mesoparticles in optofluidics. The coupling of waveguiding modes into the assembly of mesoparticles produces strong interactions and resonant conditions, which promote the transitions of the waveguiding modes. The modal response of the system depends on the distribution of packed particles above the polymeric rib waveguide which can be readily controlled under the appropriate combination of dielectrophoresis and hydrodynamic forces.

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A study of thin anodic WO3 films by electrochemical impedance spectroscopy

Cited by 58 publications

References 28 publications

Electrochemical characterization of thin passive films on Nb electrodes in H3PO4 solutions

Electrochemical characterization of thin passive films on Nb electrodes in H3PO4 solutions

Photoanodes Based on Nanostructured WO₃ for Water Splitting

Dynamic manipulation of modes in an optical waveguide using dielectrophoresis

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A study of thin anodic WO3 films by electrochemical impedance spectroscopy

Cited by 58 publications

References 28 publications

Electrochemical characterization of thin passive films on Nb electrodes in H3PO4 solutions

Electrochemical characterization of thin passive films on Nb electrodes in H3PO4 solutions

Photoanodes Based on Nanostructured WO3 for Water Splitting

Dynamic manipulation of modes in an optical waveguide using dielectrophoresis

Contact Info

Product

Resources

About

Photoanodes Based on Nanostructured WO₃ for Water Splitting