An intensity-modulated photocurrent spectroscopy study of the charge carrier dynamics of WO3/BiVO4 heterojunction systems

Rodríguez‐Gutiérrez, Ingrid; Djatoubai, Essossimna; Su, Jinzhan; Vega-Poot, Alberto; Rodríguez‐Gattorno, Geonel; Souza, Flávio L.; Oskam, Gerko

doi:10.1016/j.solmat.2019.110378

Cited by 35 publications

(37 citation statements)

References 89 publications

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“…In addition, the medium-frequency intercept on the H ′-axis increased, indicating an increase of CSE. In region (ii), the low-frequency semicircle in the first quadrant disappeared, indicating that surface recombination could not compete anymore with the charge-transfer process because of the increased potential drop across the semiconductor space charge layer. − …”

Section: Resultsmentioning

confidence: 99%

Optical, Electrochemical, and Photoelectrochemical Behavior of Copper Pyrovanadate: A Unified Theoretical and Experimental Study

et al. 2021

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Copper vanadates have been important to the development of new-generation photoelectrodes for solar water splitting and hydrogen generation. Of these, copper pyrovanadate (β-Cu2V2O7), the 2:1 ternary compound derived from CuO and V2O5, has been of particular interest to the solar fuel community. This n-type semiconductor has shown the highest photocurrent for water oxidation at 1.23 V versus reversible hydrogen electrode and exhibits good photostability in aqueous media of pH 9.2. However, further successful application of this material in photoelectrochemical (PEC) devices hinges on a comprehensive understanding of its optical, electrochemical, and optoelectronic attributes. This was done in this study by a combination of density-functional theory (for the structural, magnetic, and optical characterization) and experiments, with the latter using both small-signal (intensity-modulated photocurrent spectroscopy, IMPS) and large-signal, transient photocurrent (TP) analyses. Both IMPS and TP measurements yielded complementary and self-consistent insights into the rate constants for hole transfer and carrier recombination at the irradiated β-Cu2V2O7/electrolyte interface, specifically their dependence on the applied bias potential. The information from PEC data analyses was also self-consistent with that garnered from the optical (diffuse reflectance spectroscopy) data.

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Section: Resultsmentioning

confidence: 99%

Optical, Electrochemical, and Photoelectrochemical Behavior of Copper Pyrovanadate: A Unified Theoretical and Experimental Study

et al. 2021

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“…The crossing points on the negative and positive Re[δI photo / P in ] axes are equivalent to CSE × LHE for holes and electrons, respectively. 40 Here, CSE denotes charge separation efficiency, and LHE means light harvest efficiency. The CuO film is very thin in which the loss of light absorption is very less (∼10−30 nm, Figure S7); therefore, the LHE is almost the same due to the thickness of the C 6 H 4 NH 2 CuCl 2 I film remaining unchanged for light absorption with and without the CuO hole transport layer.…”

Section: Resultsmentioning

confidence: 99%

Photoelectrochemical Application and Charge Transport Dynamics of a Water-Stable Organic–Inorganic Halide (C₆H₄NH₂CuCl₂I) Film in Aqueous Solution

Pathak

Liu

et al. 2021

ACS Appl. Mater. Interfaces

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A water-stable thin film composed of C6H4NH2CuCl2I was fabricated using spin-coating precursor solutions that dissolved equimolar amounts of C6H4NH2I and CuCl2 in N,N-dimethylformamide. Photoelectrochemical characteristics show that the C6H4NH2CuCl2I film demonstrated a stable photocurrent (∼1 μA/cm2) in an aqueous solution under white light (11.5 mW/cm2) even after 3000 s, while exhibiting a photon-to-current efficiency of 0.093% under AM1.5 (100 mW/cm2) illumination. However, these values were significantly lower than those of the CH3NH3PbX3 (X = I, Cl) film in solid devices. The electron diffusion length L(e–) (373 nm) and hole diffusion length L(h+) (177 nm) in the C6H4NH2CuCl2I photoelectrode were significantly lower than those of CH3NH3PbX3, limiting the photoelectrochemical and photocatalysis performances. Moreover, L(h+) was shorter than L(e–) in the C6H4NH2CuCl2I photoelectrode, resulting in the hole-collecting efficiency [ηc(h+)] being lower than the electron-collecting efficiency [ηc(e–)]. A CuO interlayer was introduced as a hole transport layer for the C6H4NH2CuCl2I photoelectrode, which improved L(h+) and ηc(h+).

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“…IMPS was used to complement PEIS results, as it provides additional information on photon conversion efficiency and hole transfer kinetics. The classic theory has been elucidated by Ponomarev and Peter in their seminal work (Ponomarev and Peter, 1995), and textbook applications have been excellently explained in multiple publications (Fermín et al, 1999;Klotz et al, 2016;Zachäus et al, 2017;Antuch et al, 2018;Amano and Koga, 2020;Rodríguez-Gutiérrez et al, 2020) which were taken into consideration when interpreting the obtained spectra. Initially, measurements were carried out at 1.2 V and increasing light intensities (I 0 : 10-60 mW cm −2 at increments of 10 mW cm −2 ).…”

Section: Intensity Modulated Photocurrent Spectroscopy Studymentioning

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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An intensity-modulated photocurrent spectroscopy study of the charge carrier dynamics of WO3/BiVO4 heterojunction systems

Cited by 35 publications

References 89 publications

Optical, Electrochemical, and Photoelectrochemical Behavior of Copper Pyrovanadate: A Unified Theoretical and Experimental Study

Optical, Electrochemical, and Photoelectrochemical Behavior of Copper Pyrovanadate: A Unified Theoretical and Experimental Study

Photoelectrochemical Application and Charge Transport Dynamics of a Water-Stable Organic–Inorganic Halide (C₆H₄NH₂CuCl₂I) Film in Aqueous Solution

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

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An intensity-modulated photocurrent spectroscopy study of the charge carrier dynamics of WO3/BiVO4 heterojunction systems

Cited by 35 publications

References 89 publications

Optical, Electrochemical, and Photoelectrochemical Behavior of Copper Pyrovanadate: A Unified Theoretical and Experimental Study

Optical, Electrochemical, and Photoelectrochemical Behavior of Copper Pyrovanadate: A Unified Theoretical and Experimental Study

Photoelectrochemical Application and Charge Transport Dynamics of a Water-Stable Organic–Inorganic Halide (C6H4NH2CuCl2I) Film in Aqueous Solution

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

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Photoelectrochemical Application and Charge Transport Dynamics of a Water-Stable Organic–Inorganic Halide (C₆H₄NH₂CuCl₂I) Film in Aqueous Solution