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The role of hydrogen during Pt-Ga nanocatalyst formation

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Abstract
Hydrogen plays an essential role during the in situ assembly of tailored catalytic materials, and serves as key ingredient in multifarious chemical reactions promoted by these catalysts. Despite intensive debate for several decades, the existence and nature of hydrogen-involved mechanisms - such as hydrogen-spillover, surface migration - have not been unambiguously proven and elucidated up to date. Here, Pt-Ga alloy formation is used as a probe reaction to study the behavior and atomic transport of H and Ga, starting from Pt nanoparticles on hydrotalcite-derived Mg(Ga)(Al)O-x supports. In situ XANES spectroscopy, time-resolved TAP kinetic experiments, HAADF-STEM imaging and EDX mapping are combined to probe Pt, Ga and H in a series of H-2 reduction experiments up to 650 degrees C. Mg(Ga)(Al)O-x by itself dissociates hydrogen, but these dissociated hydrogen species do not induce significant reduction of Ga3+ cations in the support. Only in the presence of Pt, partial reduction of Ga3+ into Ga delta+ is observed, suggesting that different reaction mechanisms dominate for Pt- and Mg(Ga)(Al)O-x-dissociated hydrogen species. This partial reduction of Ga3+ is made possible by Pt-dissociated H species which spillover onto non-reducible Mg(Al)O-x or partially reducible Mg(Ga)(Al) Ox and undergo long-range transport over the support surface. Moderately mobile Ga delta+Ox migrates towards Pt clusters, where Ga delta+ is only fully reduced to Ga-0 on condition of immediate stabilization inside Pt-Ga alloyed nanoparticles.
Keywords
RAY-ABSORPTION-SPECTROSCOPY, LAYERED DOUBLE HYDROXIDES, IN-SITU XAS, PROPANE DEHYDROGENATION, ALKANE DEHYDROGENATION, AROMATIZATION CATALYSTS, ETHANE DEHYDROGENATION, THERMAL EVOLUTION, AL HYDROTALCITE, ANIONIC CLAYS

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Citation

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MLA
Filez, Matthias et al. “The Role of Hydrogen During Pt-Ga Nanocatalyst Formation.” PHYSICAL CHEMISTRY CHEMICAL PHYSICS 18.4 (2016): 3234–3243. Print.
APA
Filez, M., Redekop, E., Galvita, V., Poelman, H., Meledina, M., Turner, S., Van Tendeloo, G., et al. (2016). The role of hydrogen during Pt-Ga nanocatalyst formation. PHYSICAL CHEMISTRY CHEMICAL PHYSICS, 18(4), 3234–3243.
Chicago author-date
Filez, Matthias, Evgeniy Redekop, Vladimir Galvita, Hilde Poelman, M Meledina, S Turner, G Van Tendeloo, AT Bell, and Guy Marin. 2016. “The Role of Hydrogen During Pt-Ga Nanocatalyst Formation.” Physical Chemistry Chemical Physics 18 (4): 3234–3243.
Chicago author-date (all authors)
Filez, Matthias, Evgeniy Redekop, Vladimir Galvita, Hilde Poelman, M Meledina, S Turner, G Van Tendeloo, AT Bell, and Guy Marin. 2016. “The Role of Hydrogen During Pt-Ga Nanocatalyst Formation.” Physical Chemistry Chemical Physics 18 (4): 3234–3243.
Vancouver
1.
Filez M, Redekop E, Galvita V, Poelman H, Meledina M, Turner S, et al. The role of hydrogen during Pt-Ga nanocatalyst formation. PHYSICAL CHEMISTRY CHEMICAL PHYSICS. 2016;18(4):3234–43.
IEEE
[1]
M. Filez et al., “The role of hydrogen during Pt-Ga nanocatalyst formation,” PHYSICAL CHEMISTRY CHEMICAL PHYSICS, vol. 18, no. 4, pp. 3234–3243, 2016.
@article{8055189,
  abstract     = {Hydrogen plays an essential role during the in situ assembly of tailored catalytic materials, and serves as key ingredient in multifarious chemical reactions promoted by these catalysts. Despite intensive debate for several decades, the existence and nature of hydrogen-involved mechanisms - such as hydrogen-spillover, surface migration - have not been unambiguously proven and elucidated up to date. Here, Pt-Ga alloy formation is used as a probe reaction to study the behavior and atomic transport of H and Ga, starting from Pt nanoparticles on hydrotalcite-derived Mg(Ga)(Al)O-x supports. In situ XANES spectroscopy, time-resolved TAP kinetic experiments, HAADF-STEM imaging and EDX mapping are combined to probe Pt, Ga and H in a series of H-2 reduction experiments up to 650 degrees C. Mg(Ga)(Al)O-x by itself dissociates hydrogen, but these dissociated hydrogen species do not induce significant reduction of Ga3+ cations in the support. Only in the presence of Pt, partial reduction of Ga3+ into Ga delta+ is observed, suggesting that different reaction mechanisms dominate for Pt- and Mg(Ga)(Al)O-x-dissociated hydrogen species. This partial reduction of Ga3+ is made possible by Pt-dissociated H species which spillover onto non-reducible Mg(Al)O-x or partially reducible Mg(Ga)(Al) Ox and undergo long-range transport over the support surface. Moderately mobile Ga delta+Ox migrates towards Pt clusters, where Ga delta+ is only fully reduced to Ga-0 on condition of immediate stabilization inside Pt-Ga alloyed nanoparticles.},
  author       = {Filez, Matthias and Redekop, Evgeniy and Galvita, Vladimir and Poelman, Hilde and Meledina, M and Turner, S and Van Tendeloo, G and Bell, AT and Marin, Guy},
  issn         = {1463-9076},
  journal      = {PHYSICAL CHEMISTRY CHEMICAL PHYSICS},
  keywords     = {RAY-ABSORPTION-SPECTROSCOPY,LAYERED DOUBLE HYDROXIDES,IN-SITU XAS,PROPANE DEHYDROGENATION,ALKANE DEHYDROGENATION,AROMATIZATION CATALYSTS,ETHANE DEHYDROGENATION,THERMAL EVOLUTION,AL HYDROTALCITE,ANIONIC CLAYS},
  language     = {eng},
  number       = {4},
  pages        = {3234--3243},
  title        = {The role of hydrogen during Pt-Ga nanocatalyst formation},
  url          = {http://dx.doi.org/10.1039/c5cp07344h},
  volume       = {18},
  year         = {2016},
}

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