The Role of Surface Texture on the Photocatalytic H2 Production on TiO2

Pellegrino, Francesco; Sordello, Fabrizio; Minella, Marco; Minero, Claudio; Maurino, Valter

doi:10.3390/catal9010032

Cited by 31 publications

(22 citation statements)

References 167 publications

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“…The observed negligible photocatalytic activity of 0/TiO 2 in reaction (b 1 ) (without in-situ photodeposition of platinum), was similar to other reports [22,23] and was attributed to the high overpotential of titania for hydrogen [24]. In contrast, the activity for this reaction increased >100 times from 1Pt, which could be explained by the low (negligible) hydrogen overpotential of metallic platinum in addition to the storage of photoexcited electrons in the platinum deposits.…”

Section: Photocatalytic Activity Of Samplessupporting

confidence: 86%

Correlation of the Photocatalytic Activities of Cu, Ce and/or Pt-Modified Titania Particles with their Bulk and Surface Structures Studied by Reversed Double-Beam Photoacoustic Spectroscopy

et al. 2019

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Modified titania photocatalyst powder samples were prepared using the sol-gel method for copper (Cu) and cerium (Ce) doping and impregnation for platinum (Pt) loading. Their bulk crystalline structures were investigated using X-ray diffractometry (XRD) with the Rietveld analysis. The surface/bulk structure, surface properties, and morphologies were observed using reversed double-beam photoacoustic spectroscopy (RDB-PAS), nitrogen adsorption, and scanning electron microscopy, respectively. The results from the XRD revealed that all samples were mainly anatase (ca. 80% or higher) with small amounts of rutile and non-crystalline components. The specific surface areas of all samples were in the range of 115-155 m 2 g −1 . Ce and Cu species were mainly distributed, while Pt was potentially loaded as a partially oxidized form on the titania surface. The results from the RDB-PAS indicated the changing of the energy-resolved distribution of electron traps (ERDT) from the original titania surface upon doping of the metals (Cu, Ce, and Pt), which altered their catalytic activities. The metals photocatalytic activities with UV irradiation were measured in two representative reactions; (a) CO 2 evolution from acetic acid under the aerobic condition and (b) H 2 evolution from deaerated aqueous methanol. In reaction (a), the Cu and/or Ce modification gave almost the same or slightly lower activity compared to the non-modified titania samples, while platinum loading yielded ca. 5-6 times higher activity. For reaction (b), the photocatalytic tests were divided into two sets; without (b 1 ) and with (b 2 ) Pt deposition during the reaction. Similar enhancements of activity from the Pt loading sample (and by Cu modification) were observed in reaction (b 1 ) without in-situ platinum deposition, while the unmodified and Ce-doped samples were almost inactive. For the activities of reaction (b 2 ) with in-situ platinum deposition, the unmodified samples showed the highest activity while the Cu-modified samples showed significantly lower activity. deposition under UV-light irradiation [1][2][3][4]. The basic principle for these photocatalytic reactions is that a photoexcited electron in a conduction band and a positive hole in a valence band, created by UV photoabsorption of titania photocatalysts, will reduce and oxidize, respectively, the surface-adsorbed substrates. The band-structure model (BSM) has been used, not limited to titania photocatalysis, for the explanation of reaction mechanisms, as well as the difference in photocatalytic activities. However, the photocatalytic reaction rates probably depend on the type and surface properties of the photocatalysts. The limitations of using the BSM to describe the relationship between photocatalyst properties and photocatalytic activities are that the BSM does not include information on the surface structure/property of photocatalyst particles and it does not include the description on the surface structure, where electrons and positive holes are transferred to the surface-adsorbed subs...

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Section: Photocatalytic Activity Of Samplessupporting

confidence: 86%

Correlation of the Photocatalytic Activities of Cu, Ce and/or Pt-Modified Titania Particles with their Bulk and Surface Structures Studied by Reversed Double-Beam Photoacoustic Spectroscopy

et al. 2019

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“…As a result, the use of sacrificial agents is common to most of the artificial photocatalytic systems for H 2 production. They act as electron donors to provide electrons for proton reduction and as hole scavengers preventing the electron–hole recombination and so increasing efficiency of the process . HETPHPs use only one compound as sacrificial agent, whereas HOMPHPs and HYBPHPs can use either a compound as electron donor or a different one as proton donor, or the same compound for both functions, such as ascorbic acid or trimethylamine.…”

Section: Influence Of System Units On Photocatalytic Performancementioning

confidence: 99%

Comprehensive review and future perspectives on the photocatalytic hydrogen production

Corredor

Rivero

Rangel

et al. 2019

J of Chemical Tech & Biotech

161

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Hydrogen represents a renewable energy alternative that may positively contribute to get over the global energy crisis while at the same time reducing its environmental burden. Overcoming the challenge of reaching this potential could be helped by careful choice of hydrogen (H2) sources. Photocatalytic generation of H2, although a minor alternative, appears to be a very good option at the time that liquid wastes are being degraded; therefore, this approach has given rise to an increasing number of interesting studies. Here, we aim to provide an integrated overview of the different photocatalytic, heterogeneous, homogeneous and hybrid systems. First, we categorize the units and mechanisms that take part in the photocatalytic process, and secondly we analyze their role and draw comparative conclusions. Thus, we analyze the role of (i) the electron source to carry out proton reduction, (ii) the proton source, which can be free protons in the medium or a proton donor compound, (iii) the catalyst nature and concentration, and (iv) the photosensitizer nature and concentration. We also provide an analysis of the influence of the solvent, especially in homogenous systems as well as the influence of pH. We provide a comparison of the photocatalytic performance, highlighting the advantages and disadvantages, of different systems. Thus, this review is, on the one hand, an update on the state of the art of photocatalytic generation of H2 from a full perspective that integrates homogeneous, heterogeneous and hybrid systems, and, on the other, a source of useful information for future research. © 2019 Society of Chemical Industry

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“…While various hole scavengers have been widely investigated for TiO2 nanoparticle suspensions (see for example the overviews given in refs. [18,26,27]), a systematic comparison in the case of anodic TiO2 nanotubes is entirely missing.…”

mentioning

confidence: 99%

Effect of different hole scavengers on the photoelectrochemical properties and photocatalytic hydrogen evolution performance of pristine and Pt-decorated TiO2 nanotubes

Denisov

Yoo

Schmuki

2019

Electrochimica Acta

100

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TiO2 nanotubes have been investigated in photoelectrochemistry and photocatalysis for more than a decade. However, up to now, a systematic investigation of different hole scavengers is still lacking. Here we investigate the effect of the most relevant sacrificial hole scavengers on the photoelectrochemical properties and photocatalytic H2 evolution performance of pristine and Pt-decorated anodic TiO2 nanotubes. We examine methanol, isopropanol, ethylene glycol, EDTA-Na2, as well as Na2SO3, and find that the incident photocurrent conversion efficiency (IPCE) of the TiO2 nanotubes in 0.1 M Na2SO4 electrolytes increases by 1.8-3.1 times, depending on the used hole scavenger. The efficiency increases in the sequence Na2SO3 < isopropanol < MeOH < ethylene glycol < EDTA-Na2. In presence of any hole scavenger, for nanotubes in the length-range of 2-10 µm, the photocurrent spectra and the ICPE magnitude are independent of the tube length. The photocurrent onset potential (optical flatband potential) is significantly affected by the different type of scavengers, in line with their red-ox potential. Under open circuit conditions (photocatalytic conditions), organic hole scavengers lead to a 10.0-28.8 times higher H2 production by TiO2 nanotubes than the scavenger-free case, with a sequence MeOH > i-PrOH > EDTA-Na2 > EG, while a detrimental effect of Na2SO3 is observed. These results are compared to results obtained for TiO2 particles, and discussed in terms of various concepts in the literature.

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The Role of Surface Texture on the Photocatalytic H2 Production on TiO2

Cited by 31 publications

References 167 publications

Correlation of the Photocatalytic Activities of Cu, Ce and/or Pt-Modified Titania Particles with their Bulk and Surface Structures Studied by Reversed Double-Beam Photoacoustic Spectroscopy

Correlation of the Photocatalytic Activities of Cu, Ce and/or Pt-Modified Titania Particles with their Bulk and Surface Structures Studied by Reversed Double-Beam Photoacoustic Spectroscopy

Comprehensive review and future perspectives on the photocatalytic hydrogen production

Effect of different hole scavengers on the photoelectrochemical properties and photocatalytic hydrogen evolution performance of pristine and Pt-decorated TiO2 nanotubes

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