Morphology evolution of the anodized tin oxide film during early formation stages at relatively high constant potential

Cao, Jinwei; Gao, Zhaoqing; Wang, Chen; Hussain, Muhammad Muzammal; Wang, Weiqiang; Gu, Qidi; Dong, Chong; Ma, Haitao; Wang, Yunpeng

doi:10.1016/j.surfcoat.2020.125592

Cited by 40 publications

(26 citation statements)

References 35 publications

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“…Sodium hypophosphite was added as it prevents accumulation of excess oxygen on the pore walls during anodization (Zhu et al, 2008;Cao et al, 2020), also it can affect the growth mechanism of the film by reducing some of the components (Yang et al, 2006;Gan et al, 2012;Chu et al, 2014). Moreover, the photocatalytic activity of WO 3 films obtained without hypophosphite was inferior as our preliminary experiments showed.…”

Section: Anodization Procedures and Treatment Of Wo 3 Filmsmentioning

confidence: 99%

Improved Photocatalytic Water Splitting Activity of Highly Porous WO3 Photoanodes by Electrochemical H+ Intercalation

Levinas¹,

Цынцару

Murauskas³

et al. 2021

Front. Chem. Eng.

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WO3 photoanodes are widely used in photoelectrochemical catalysis, but typically the as-synthesized material is annealed before application. It is therefore desirable to explore less energy-intensive treatments. In this study, WO3 films of up to 3.9 μm thickness were obtained by galvanostatic anodization of tungsten foil in a neutral-pH Na2SO4 and NaF electrolyte, also containing a NaH2PO2 additive (to suppress O2 accumulation on the pore walls). Additionally, the WO3 photoanodes were modified by applying a cathodic reduction (H+ intercalation) and anodic activation treatment in-situ. XPS spectra revealed that intercalation modifies WO3 films; the amount of W5+-O and O-vacancy bonds was increased. Furthermore, subsequent activation leads to a decrease of the W5+ signal, but the amount of O-vacancy bonds remains elevated. The as-prepared and reduced (intercalated & activated) films were tested as OER photoanodes in acidic 0.1 M Na2SO4 media, under illumination with a 365 nm wavelength LED. It was observed that thinner films generated larger photocurrents. The peculiarities detected by XPS for reduced films correlate well with their improved photocatalytic activity. Photo-electrochemical impedance and intensity modulated photocurrent spectroscopies were combined with steady-state measurements in order to elucidate the effects of H+ intercalation on photoelectrochemical performance. The reduction results in films with enhanced photoexcited charge carrier generation/separation, improved conductivity, and possibly even suppressed bulk recombination. Thus, the intercalation & activation adopted in this study can be reliably used to improve the overall activity of as-synthesized WO3 photoanodes, and particularly of those that are initially poorly photoactive.

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Section: Anodization Procedures and Treatment Of Wo 3 Filmsmentioning

confidence: 99%

Improved Photocatalytic Water Splitting Activity of Highly Porous WO3 Photoanodes by Electrochemical H+ Intercalation

Levinas¹,

Цынцару

Murauskas³

et al. 2021

Front. Chem. Eng.

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“…2 is a diagram of the 'oxygen bubble model' growth. According to the 'oxygen bubble model' [32][33][34][35][36][37][38] and ionic current and electronic current theories. [39][40][41][42][43][44][45] Two reactions happened at the anode.…”

Section: Temperature Control Anodization Of Timentioning

confidence: 99%

“…According to the 'oxygen bubble model' [32][33][34][35][36][37][38] and the ionic current and electronic current theories, [39][40][41][42][43][44][45] when the temperature is high, the magnitude of electronic current and ionic current is large, so the mold effect is obvious, regular nanotubes can be formed, as shown in Fig. 1a.…”

Section: Temperature Control Anodization Of Timentioning

confidence: 99%

“…That is because the eld-assisted dissolution reaction itself has nothing to do with the current. A new explanation for the decreasing current under low temperature is given based on the 'oxygen bubble model' [32][33][34][35][36][37][38] and the ionic current and electronic current theories. [39][40][41][42][43][44][45] We propose that the electronic current, rather than the eld-assisted dissolution, plays an important role in the growth of nanotubes.…”

Section: Introductionmentioning

confidence: 99%

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Debunking the essential effect of temperature and voltage on the current curve and the nanotube morphology

et al. 2022

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“…26,43,44 The ionic current causes the growth of the barrier oxide layer to flow upward around the oxygen bubble mold, creating the nanotube walls. [45][46][47][48][49][50] Garcia-Vergara et al 43 concluded that the viscous flow model and the field-assisted dissolution theories are completely opposite in the way of the pore or nanotube formation. 43 However, there is little direct evidence on whether nanotube embryos are formed by the field-assisted dissolution or by the 'oxygen bubble model'.…”

Section: Introductionmentioning

confidence: 99%

Evidence of oxygen bubbles forming nanotube embryos in porous anodic oxides

Gong

et al. 2021

Nanoscale Adv.

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Morphology evolution of the anodized tin oxide film during early formation stages at relatively high constant potential

Cited by 40 publications

References 35 publications

Improved Photocatalytic Water Splitting Activity of Highly Porous WO3 Photoanodes by Electrochemical H+ Intercalation

Improved Photocatalytic Water Splitting Activity of Highly Porous WO3 Photoanodes by Electrochemical H+ Intercalation

Debunking the essential effect of temperature and voltage on the current curve and the nanotube morphology

Evidence of oxygen bubbles forming nanotube embryos in porous anodic oxides

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