On the “possible” synergism of the different phases of TiO 2 in photo-catalysis for hydrogen production

Handle URI:
http://hdl.handle.net/10754/625592
Title:
On the “possible” synergism of the different phases of TiO 2 in photo-catalysis for hydrogen production
Authors:
Wahab, A.K.; Ould-Chikh, Samy ( 0000-0002-3486-0944 ) ; Meyer, K.; Idriss, H.
Abstract:
The effect of TiO2 phase composition on the photocatalytic hydrogen production of water/ethanol (95/5 volume ratio) has been studied in order to understand the structural effect (and associated electronic properties) on the reaction within the so called “synergistic effect” concept. Within the investigated series of 1wt.% Pt/TiO2 with initial particle dimension of ca. 15nm the highest hydrogen production rate per unit area was observed for catalysts composed of 80% anatase, 18% rutile and 2% brookite. The associated particle sizes for this catalyst were 44, 82 and 33nm for the three phases, respectively. XRD patterns analyzed by the Rietveld method as well as X-ray absorption near-edge spectra (XANES) of the Ti K-edge mapped the phase transformation from anatase/brookite to rutile where it appears that the brookite phase is initially transformed to anatase phase. XRD patterns and Raman shift were found to be more sensitive to subtle changes in phase composition when compared to UV-vis absorbance or XANES of the Ti K-edge. The photocatalytic reaction for the complete series was conducted in identical condition and with excess photon flux in order to extract accurate reaction rates. In addition to the observed multi-phase effects on the reaction rate, other parameters extracted from the Rietveld refinement of the X-ray diffraction patterns were found to be useful. In particular, at the narrow window where the reaction rate was found to be maximum, the c-dimension of the anatase phase had values in the range 9.510–9.515Å. These c-dimension values are between those observed for nanoparticles with less than 20nm in size and those for larger particles with a size above 50nm. Results from this work indicate that the synergism between anatase and rutile on the photocatalytic reaction for hydrogen production, often attributed to increase the charge carrier life time, may be linked to the lattice expansion of the anatase phase which in turn would affect its electronic/catalytic properties.
KAUST Department:
SABIC - Corporate Research and Innovation Center (CRI) at KAUST; KAUST Catalysis Center (KCC); Physical Sciences and Engineering (PSE) Division
Citation:
Wahab AK, Ould-Chikh S, Meyer K, Idriss H (2017) On the “possible” synergism of the different phases of TiO 2 in photo-catalysis for hydrogen production. Journal of Catalysis 352: 657–671. Available: http://dx.doi.org/10.1016/j.jcat.2017.04.033.
Publisher:
Elsevier BV
Journal:
Journal of Catalysis
Issue Date:
19-May-2017
DOI:
10.1016/j.jcat.2017.04.033
Type:
Article
ISSN:
0021-9517
Sponsors:
The authors thank the contribution of Dr. Maarten Nachtegaal at Paul Scherrer Institute, Swiss Light Source, for conducting the X-ray absorption measurements. The TEM and HRTEM of Fig. 11 was conducted by Prof. Jordi Llorca, UPC (Spain).
Additional Links:
http://www.sciencedirect.com/science/article/pii/S0021951717301549
Appears in Collections:
Articles; Physical Sciences and Engineering (PSE) Division; KAUST Catalysis Center (KCC)

Full metadata record

DC FieldValue Language
dc.contributor.authorWahab, A.K.en
dc.contributor.authorOuld-Chikh, Samyen
dc.contributor.authorMeyer, K.en
dc.contributor.authorIdriss, H.en
dc.date.accessioned2017-10-03T12:49:28Z-
dc.date.available2017-10-03T12:49:28Z-
dc.date.issued2017-05-19en
dc.identifier.citationWahab AK, Ould-Chikh S, Meyer K, Idriss H (2017) On the “possible” synergism of the different phases of TiO 2 in photo-catalysis for hydrogen production. Journal of Catalysis 352: 657–671. Available: http://dx.doi.org/10.1016/j.jcat.2017.04.033.en
dc.identifier.issn0021-9517en
dc.identifier.doi10.1016/j.jcat.2017.04.033en
dc.identifier.urihttp://hdl.handle.net/10754/625592-
dc.description.abstractThe effect of TiO2 phase composition on the photocatalytic hydrogen production of water/ethanol (95/5 volume ratio) has been studied in order to understand the structural effect (and associated electronic properties) on the reaction within the so called “synergistic effect” concept. Within the investigated series of 1wt.% Pt/TiO2 with initial particle dimension of ca. 15nm the highest hydrogen production rate per unit area was observed for catalysts composed of 80% anatase, 18% rutile and 2% brookite. The associated particle sizes for this catalyst were 44, 82 and 33nm for the three phases, respectively. XRD patterns analyzed by the Rietveld method as well as X-ray absorption near-edge spectra (XANES) of the Ti K-edge mapped the phase transformation from anatase/brookite to rutile where it appears that the brookite phase is initially transformed to anatase phase. XRD patterns and Raman shift were found to be more sensitive to subtle changes in phase composition when compared to UV-vis absorbance or XANES of the Ti K-edge. The photocatalytic reaction for the complete series was conducted in identical condition and with excess photon flux in order to extract accurate reaction rates. In addition to the observed multi-phase effects on the reaction rate, other parameters extracted from the Rietveld refinement of the X-ray diffraction patterns were found to be useful. In particular, at the narrow window where the reaction rate was found to be maximum, the c-dimension of the anatase phase had values in the range 9.510–9.515Å. These c-dimension values are between those observed for nanoparticles with less than 20nm in size and those for larger particles with a size above 50nm. Results from this work indicate that the synergism between anatase and rutile on the photocatalytic reaction for hydrogen production, often attributed to increase the charge carrier life time, may be linked to the lattice expansion of the anatase phase which in turn would affect its electronic/catalytic properties.en
dc.description.sponsorshipThe authors thank the contribution of Dr. Maarten Nachtegaal at Paul Scherrer Institute, Swiss Light Source, for conducting the X-ray absorption measurements. The TEM and HRTEM of Fig. 11 was conducted by Prof. Jordi Llorca, UPC (Spain).en
dc.publisherElsevier BVen
dc.relation.urlhttp://www.sciencedirect.com/science/article/pii/S0021951717301549en
dc.subjectPhotocatalysisen
dc.subjectSynergismen
dc.subjectTiO2 anataseen
dc.subjectTiO2 rutileen
dc.subjectHydrogen productionen
dc.subjectReaction rateen
dc.titleOn the “possible” synergism of the different phases of TiO 2 in photo-catalysis for hydrogen productionen
dc.typeArticleen
dc.contributor.departmentSABIC - Corporate Research and Innovation Center (CRI) at KAUSTen
dc.contributor.departmentKAUST Catalysis Center (KCC)en
dc.contributor.departmentPhysical Sciences and Engineering (PSE) Divisionen
dc.identifier.journalJournal of Catalysisen
dc.contributor.institutionDepartment of Chemistry and Applied Biosciences, Institute for Chemical and Bioengineering, ETH Zürich, Wolfgang-Pauli-Str. 10, CH-8093 Zürich, Switzerlanden
kaust.authorWahab, A.K.en
kaust.authorOuld-Chikh, Samyen
kaust.authorIdriss, H.en
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