Carrier density and interfacial kinetics of mesoporous TiO2 in aqueous electrolyte determined by impedance spectroscopy

Giménez, Sixto; Dunn, Halina K.; Rodenas, Pau; Fabregat‐Santiago, Francisco; Miralles, Sara G.; Barea, Eva M.; Trevisan, Roberto; Guerrero, Antonio; Bisquert, Juan

doi:10.1016/j.jelechem.2011.12.019

Cited by 57 publications

(68 citation statements)

References 34 publications

(40 reference statements)

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“…71,72 In the present work, EIS spectra of both pristine and Gd 3+ doped TiO 2 electrodes were recorded for low and high light intensities at different applied potential (−0.8 to 0.8 V vs RHE). The chemical capacitance values are estimated using appropriate equivalent circuit previously reported by Gimenz et al 65 and summarized in Fig. 8.…”

Section: (Degrees)mentioning

confidence: 99%

Enhanced Photoelectrocatalytic Water Splitting at Hierarchical Gd³⁺:TiO₂Nanostructures through Amplifying Light Reception and Surface States Passivation

Sudhagar

Devadoss

Nakata

et al. 2014

J. Electrochem. Soc.

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The influence of rare earth gadolinium (Gd 3+ ) ion doping on optical and photoelectrochemical properties of TiO 2 is studied. The hierarchical clump-type TiO 2 nanostructure was fabricated using poly-vinyl acetate as soft-template. The optical absorbance quantity of TiO 2 was strikingly promoted at bandgap energy region (380 nm) by Gd 3+ doping, as well as it extend a wide absorbance in visible wavelength region (400 -800 nm) elucidating the sub-bandgap formation. As a result, Gd 3+ :TiO 2 exhibits high photocurrent density than undoped TiO 2 in photoelectrocatalytic experiments. Another plausible reason for enhancing the photocurrent density at Gd 3+ :TiO 2 was analyzed through electrochemical impedance spectroscopy. The underlying mechanism of surface states controlled charge transfer at TiO 2 /electrolyte interfaces affected the photoelectrocatalytic hydrogen fuel generation, and compete with Gd 3+ ion doping through bottlenecking of photoelectrons trapping at surface states. The improved charge separation (e − /h + ) at Gd 3+ :TiO 2 result effective photoelectron collection and thus yield 180 % higher hydrogen gas (∼ 2.34 mL.h −1 .cm −2 ) generation compare to pristine TiO 2 (1.28 mL.h −1 .cm −2 ) under UV light irradiation. The improved optical and charge transfer characteristics of hierarchical TiO 2 by Gd 3+ ions can be implemented to wide range of other metal oxide based photocatalytic fuel generation. The photoelectrocatalytic (PEC) water oxidation phenomenon configured with light and semiconductor opens new pathways in cost-effective fuel generation (hydrogen and oxygen) using water as feed stock.1 Merits counting the zero-emission of harmful CO 2 into environment, 2 possibility of beneficial simultaneous process of pollutant treatment, 3,4 and/or biomass reformation toward hydrogen fuel generation foster PEC water oxidation as an emerging technology in green energy fuels. Nanostructured titanium dioxide (TiO 2 ) is one of the most studied candidates in PEC applications including fuel generation, 5-7 organic pollutant degradation, 8,9 photoelectrochemical biosensors, 10,11 photocatalytic self-cleaning coatings 12,13 and antimicrobial coatings.14 The clean fuel generation from photoelectrolysis of water using TiO 2 mesoporous electrodes received much attention, despite its bandgap (3.2 eV) lies in UV region, due to the appreciable chemical stability and environmentally begin nature. One of the approaches to promote PEC performance of TiO 2 in solar to fuel generation is extending the visible light activity of TiO 2 by bandgap modification through doping with metal ions (Fe,15 21 or inducing defects in crystallite lattice. 22,23 However the doping material perhaps shift the TiO 2 valence band more negative than the water oxidation potential 1.2 V vs RHE, which in turn might affect the PEC water oxidation rates. 24The lanthanide (Ln) rare earth ion (RE) doping at TiO 2 matrix is an alternative approach to enhance the light reception at TiO 2 . Furthermore, RE ions doping can alter the bandgap structure o...

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Section: (Degrees)mentioning

confidence: 99%

Enhanced Photoelectrocatalytic Water Splitting at Hierarchical Gd³⁺:TiO₂Nanostructures through Amplifying Light Reception and Surface States Passivation

Sudhagar

Devadoss

Nakata

et al. 2014

J. Electrochem. Soc.

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“…Concerning the photoelectrochemical activity of bare TiO 2 electrodes, however, there are only a few reports investigating the effect of the number of screen‐printed layers. For instance, Gimenez et al . observed for screen‐printed electrodes with three different thicknesses (2.5 μm, 5 μm and 10 μm) that the most active ones for the water oxidation reaction are the 2.5 μm and 10 μm electrodes.…”

Section: Introductionmentioning

confidence: 99%

Tailoring the Photoelectrochemical Activity of TiO₂ Electrodes by Multilayer Screen‐Printing

et al. 2019

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Screen-printing is a commonly used method for the preparation of photoelectrodes. Although previous studies have explored the effect of the number of printed layers on the efficiency of dye-sensitized solar cells, its interplay with the photoelectrocatalytic properties of the electrodes has rarely been examined. This study focuses on this issue by studying the photoelectrocatalytic oxidation of methanol over TiO 2 electrodes. Incident photon-to-current efficiencies reached 87 % at the optimal conditions of monochromatic (338 nm) irradiation of one-layer films at 0.2 V vs NHE. However, the irradiation wavelength and applied bias strongly influenced the relative behavior of the films. For instance, at 0.5 V and 327 nm irradiation, the one-layer electrode was 6 times more efficient than the four-layer one, while at 385 nm the four-layer electrode was 3.5 times more efficient. The results were explained on the basis of differing light absorption properties and charge carrier lifetimes. Modelling and quantification of the electron diffusion length (5.7 μm) helped to explain why the two-layer electrode (4.89 μm thick) showed the most consistent efficiencies across all conditions. Complementarily, transient absorption spectroscopy was used to correlate the thicknesses with charge carrier lifetimes. Electron transfer to FTO was apparent only for the thinner electrode. Our work shows that the optimization of photoelectrocatalytic processes should include the number of layers as a key variable.[a] C.The concentration of the transients follows a linear relation with the change in reflectance as long as the latter is lower than 10 %. [33] The measurements were performed in the wavelength range from 400 to 630 nm in 10 nm steps, 50 shots were averaged, and the data points were reduced to 200. 4 5 6 7 8

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“…Figure 6 shows the EIS response for samples A and B as a function of the applied potential. For both samples, we can observe the same behavior, one potential-dependent semicircle, which is related to the charge-transfer resistance, associated to the oxygen evolution reaction, combined with the chemical capacitance (C μ ) [37]. The EIS data were fitted using the appropriate equivalent circuit model, as showed in Fig.…”

Section: Resultsmentioning

confidence: 97%

Photoelectrochemical characterization of ITO/TiO2 electrodes obtained by cathodic electrodeposition from aqueous solution

Marchesi

Freitas

Spada

et al. 2015

J Solid State Electrochem

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In the present work, the photoelectrochemical characterization of ITO/TiO 2 electrodes electrosynthesized at two distinct TiO 2 film charges (0.35 and 1.00 C) was performed. Scanning electron microscopy presented a globular-like nanostructure and a typical morphology that are dependent on the growing charge, where the photoelectrode synthesized at 0.35 C presented a more homogeneous morphology. Such dependence was also observed at the photoelectrochemical response, once the photoactivity for the photoelectrode synthesized at 0.35 C was better than the photoelectrode synthesized at 1.00 C, which was explained by the surface recombination process and the electron lifetime. In order to explore the charge-transfer process and the displacement of the quasi-Fermi level upon illumination, electrochemical impedance spectroscopy (EIS) was performed at distinct applied potentials. EIS results corroborate the previous results, presenting a higher charge-transfer resistance and a lower chemical capacitance for the 1.00 C electrode film, the last one in accordance with the open-circuit voltage decay.

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Carrier density and interfacial kinetics of mesoporous TiO2 in aqueous electrolyte determined by impedance spectroscopy

Cited by 57 publications

References 34 publications

Enhanced Photoelectrocatalytic Water Splitting at Hierarchical Gd³⁺:TiO₂Nanostructures through Amplifying Light Reception and Surface States Passivation

Enhanced Photoelectrocatalytic Water Splitting at Hierarchical Gd³⁺:TiO₂Nanostructures through Amplifying Light Reception and Surface States Passivation

Tailoring the Photoelectrochemical Activity of TiO₂ Electrodes by Multilayer Screen‐Printing

Photoelectrochemical characterization of ITO/TiO2 electrodes obtained by cathodic electrodeposition from aqueous solution

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Carrier density and interfacial kinetics of mesoporous TiO2 in aqueous electrolyte determined by impedance spectroscopy

Cited by 57 publications

References 34 publications

Enhanced Photoelectrocatalytic Water Splitting at Hierarchical Gd3+:TiO2Nanostructures through Amplifying Light Reception and Surface States Passivation

Enhanced Photoelectrocatalytic Water Splitting at Hierarchical Gd3+:TiO2Nanostructures through Amplifying Light Reception and Surface States Passivation

Tailoring the Photoelectrochemical Activity of TiO2 Electrodes by Multilayer Screen‐Printing

Photoelectrochemical characterization of ITO/TiO2 electrodes obtained by cathodic electrodeposition from aqueous solution

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Enhanced Photoelectrocatalytic Water Splitting at Hierarchical Gd³⁺:TiO₂Nanostructures through Amplifying Light Reception and Surface States Passivation

Enhanced Photoelectrocatalytic Water Splitting at Hierarchical Gd³⁺:TiO₂Nanostructures through Amplifying Light Reception and Surface States Passivation

Tailoring the Photoelectrochemical Activity of TiO₂ Electrodes by Multilayer Screen‐Printing