Analysis of the factors controlling performances of Au-modified TiO 2  nanotube array based photoanode in photo-electrocatalytic (PECa) cells

Ampelli, Claudio; Tavella, Francesco; Genovese, Chiara; Perathoner, Siglinda; Favaro, Marco

doi:10.1016/j.jechem.2016.11.004

Cited by 31 publications

(14 citation statements)

References 56 publications

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“…Here, we report on the study of the bulk and surface state recombination processes in single and mixed-phase TiO 2 nanotube photoanodes by employing IMPS and IMVS to gain information on non-radiative recombination (i.e., electron/hole recombination mediated by emission of phonons). Nanotubes are chosen as a suitable morphology for TiO 2 photoanodes due to their high surface to volume ratio, preferential electron transport towards the Ti back-contact, and a scalable synthetic process by electrochemical anodization [7,24,[41][42][43][44]. Further, we correlate the obtained results to electrical characteristics of our photoelectrodes retrieved from EIS and to the information on radiative recombination (i.e., electron/hole recombination mediated by emission of photons) gained by photoluminescence spectroscopy.…”

Section: Introductionmentioning

confidence: 90%

Radiative and Non-Radiative Recombination Pathways in Mixed-Phase TiO2 Nanotubes for PEC Water-Splitting

et al. 2019

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Anatase and rutile mixed-phase TiO2 with an ideal ratio has been proven to significantly enhance photoelectrochemical (PEC) activity in water-splitting applications due to suppressing the electron–hole recombination. However, the mechanism of this improvement has not been satisfactory described yet. The PEC water oxidation (oxygen evolution) at the interface of TiO2 photoanode and electrolyte solution is determined by the fraction of the photogenerated holes that reach the solution and it is defined as the hole transfer efficiency. The surface and bulk recombination processes in semiconductor photoanodes majorly influence the hole transfer efficiency. In this work, we study the hole transfer process involved in mixed-phase TiO2 nanotube arrays/solution junction using intensity-modulated photocurrent and photovoltage spectroscopy (IMPS and IMVS); then, we correlate the obtained hole transfer rate constants to (photo)electrochemical impedance spectroscopy (PEIS) measurements. The results suggest that the enhanced performance of the TiO2 mixed-phase is due to the improved hole transfer rate across the TiO2/liquid interface as well as to the decrease in the surface trap recombination of the holes.

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Section: Introductionmentioning

confidence: 90%

Radiative and Non-Radiative Recombination Pathways in Mixed-Phase TiO2 Nanotubes for PEC Water-Splitting

et al. 2019

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“…The generated hydrogen can be used as a primary energy source (e.g., in hydrogen fuel cells) or for the production of synthetic fuels via Fischer-Tropsch synthesis. 8,9,10,11,12,13,14 The successful implementation of solar hydrogen into the energy landscape would further spread the usage of solar energy technologies and could potentially secure a large fraction of the world's future energy needs.…”

Section: Introductionmentioning

confidence: 99%

Chemical, Structural, and Electronic Characterization of the (010) Surface of Single Crystalline Bismuth Vanadate

et al. 2018

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We have structurally, chemically and electronically characterized the most stable (010) surface of a Mo-doped BiVO 4 single crystal. Low energy electron diffraction (LEED) reveals that the surface is not significantly reconstructed from a bulk termination of the crystal. Synchrotron based X-ray spectroscopies indicate no surface enhancement of any of the crystal constituents and that the Mo dopant occupies tetrahedral sites by substituting for V at the surface. Using resonant photoemission to study the valence band structure as the V L 3 edge is scanned we observe an intra-band gap state associated with reduced vanadium formed by the Mo doping. This state is likely associated with small polaron formation at the surface. This feature is enhanced at a photon energy that is not resonant with any of the main features in the absorption spectrum of the pristine BiVO 4. This indicates that the additional electron from Mo doping likely induces further distortion of the VO 4 tetrahedral units and generates a new conduction band state either by splitting of the V dz 2 states or by hybridization of V d zx and V dz 2 states. We measure a work function of 5.15 eV for the BiVO 4 (010) surface. Measurement of the work function allows us to recast the electronic energy levels onto the normal hydrogen electrode scale for comparison to the standard reduction and oxidation potentials of water. This detailed study should provide a basis for future work aimed at a molecular level understanding of BiVO 4 /electrolyte interfaces used for photoelectrochemical water splitting.

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“…In addition, often noble metal nanoparticles (Au, Pt, etc.) have been used [25][26][27][28], while for both cost and sustainability motivations (use of non-critical raw materials) it would be preferable to use earth-abundant elements for the development of photoanodes. Among the interesting transition metals to improve semiconductor photocatalytic properties, one is copper oxide.…”

Section: Introductionmentioning

confidence: 99%

Role of CuO in the modification of the photocatalytic water splitting behavior of TiO2 nanotube thin films

Brito

Tavella

Genovese

et al. 2018

Applied Catalysis B: Environmental

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The role of CuO nanoparticles decorating TiO 2 nanotubes (TNT) thin film photoanodes in the behavior of photoelectrocatalytic (PEC) cells for water splitting reaction is investigated. CuO is present mainly as small nanoparticles of few nanometer decorating the internal walls of the TiO 2 nanotubes. Their presence improves i) the photocurrent behavior, ii) the H 2 generation rate by water splitting in a full PEC device (without application of a bias) and iii) the solar-to-hydrogen (STH) efficiency. The increase is about 20% with respect to parent TNT photoanodes using open spectrum light from a solar simulator and about 50% increase using AM 1.5G filtered light from a solar simulator. An STH efficiency over 2% in the full PEC cell is observed in the best conditions. IPCE (incident photon to current conversion efficiency) measurements clearly evidence that the presence of CuO nanoparticles induce an enhanced IPCE in the 300-340 nm region. The increase in the performances in water splitting is mainly associated to the transient generation of a p-n junction between the Cu x O nanoparticles and TNT upon illumination, which enhances photocurrent density by promoting charge separation.

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Analysis of the factors controlling performances of Au-modified TiO 2 nanotube array based photoanode in photo-electrocatalytic (PECa) cells

Cited by 31 publications

References 56 publications

Radiative and Non-Radiative Recombination Pathways in Mixed-Phase TiO2 Nanotubes for PEC Water-Splitting

Radiative and Non-Radiative Recombination Pathways in Mixed-Phase TiO2 Nanotubes for PEC Water-Splitting

Chemical, Structural, and Electronic Characterization of the (010) Surface of Single Crystalline Bismuth Vanadate

Role of CuO in the modification of the photocatalytic water splitting behavior of TiO2 nanotube thin films

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