Role of surface reconstruction on Cu/TiO2 nanotubes for CO2 conversion

Chao Liu, Scott L. Nauert, Marco A. Alsina, Dingdi Wang, Alexander Grant, Kai He, Eric Weitz*, Michael Nolan, Kimberly A Gray, Justin M Notestein

*Corresponding author for this work

Research output: Contribution to journalArticle

Abstract

Carbon dioxide hydrogenation to CO via the reverse water gas shift (RWGS) reaction is one route to integrate CO2 utilization into the chemical industry. TiO2 supported Cu catalysts are known to be active for RWGS, but Cu is shown here to behave differently on TiO2 nanotubes (TiNT) vs TiO2 nanoparticles (TiNP). Whereas nanoparticle supports give low rates that are hardly changed by added Cu, the nanotube supports yield much higher activity and three distinct behaviors as the Cu surface density increases. At low surface densities (0.3 Cu/nm2), active Cu-O-Ti sites are created that have low apparent activation energies. At high surface densities (6 Cu/nm2), Cu nanoparticles on TiNT are formed, and reaction barriers are lowered when both Cu and TiNT surfaces are accessible. At intermediate surface densities, metallic Cu domains are engulfed by a TiOx overlayer formed during H2 pretreatment, akin to those formed by classical strong metal support interactions (SMSI). These reduced layers are markedly more active for RWGS than the initial TiNT surfaces, but have similar activation barriers, which are higher than those for which both Cu and TiNP surfaces are exposed. These catalytic findings are supported by computational modeling, in situ IR, UV–vis, and X-ray absorption spectroscopies, and they provide insight into an important reaction for CO2 utilization.

Original languageEnglish (US)
Article number117754
JournalApplied Catalysis B: Environmental
Volume255
DOIs
StatePublished - Oct 15 2019

Fingerprint

Surface reconstruction
Nanotubes
Water gas shift
Nanoparticles
gas
X ray absorption spectroscopy
chemical industry
atomic absorption spectroscopy
Carbon Monoxide
Chemical industry
nanotube
Carbon Dioxide
activation energy
water
X-ray spectroscopy
Hydrogenation
Carbon dioxide
Activation energy
carbon dioxide
Metals

Keywords

  • CO conversion
  • Reverse water-gas shift
  • SMSI
  • Spectroscopy
  • Supported metals

ASJC Scopus subject areas

  • Catalysis
  • Environmental Science(all)
  • Process Chemistry and Technology

Cite this

Liu, Chao ; Nauert, Scott L. ; Alsina, Marco A. ; Wang, Dingdi ; Grant, Alexander ; He, Kai ; Weitz, Eric ; Nolan, Michael ; Gray, Kimberly A ; Notestein, Justin M. / Role of surface reconstruction on Cu/TiO2 nanotubes for CO2 conversion. In: Applied Catalysis B: Environmental. 2019 ; Vol. 255.
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abstract = "Carbon dioxide hydrogenation to CO via the reverse water gas shift (RWGS) reaction is one route to integrate CO2 utilization into the chemical industry. TiO2 supported Cu catalysts are known to be active for RWGS, but Cu is shown here to behave differently on TiO2 nanotubes (TiNT) vs TiO2 nanoparticles (TiNP). Whereas nanoparticle supports give low rates that are hardly changed by added Cu, the nanotube supports yield much higher activity and three distinct behaviors as the Cu surface density increases. At low surface densities (0.3 Cu/nm2), active Cu-O-Ti sites are created that have low apparent activation energies. At high surface densities (6 Cu/nm2), Cu nanoparticles on TiNT are formed, and reaction barriers are lowered when both Cu and TiNT surfaces are accessible. At intermediate surface densities, metallic Cu domains are engulfed by a TiOx overlayer formed during H2 pretreatment, akin to those formed by classical strong metal support interactions (SMSI). These reduced layers are markedly more active for RWGS than the initial TiNT surfaces, but have similar activation barriers, which are higher than those for which both Cu and TiNP surfaces are exposed. These catalytic findings are supported by computational modeling, in situ IR, UV–vis, and X-ray absorption spectroscopies, and they provide insight into an important reaction for CO2 utilization.",
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Role of surface reconstruction on Cu/TiO2 nanotubes for CO2 conversion. / Liu, Chao; Nauert, Scott L.; Alsina, Marco A.; Wang, Dingdi; Grant, Alexander; He, Kai; Weitz, Eric; Nolan, Michael; Gray, Kimberly A; Notestein, Justin M.

In: Applied Catalysis B: Environmental, Vol. 255, 117754, 15.10.2019.

Research output: Contribution to journalArticle

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T1 - Role of surface reconstruction on Cu/TiO2 nanotubes for CO2 conversion

AU - Liu, Chao

AU - Nauert, Scott L.

AU - Alsina, Marco A.

AU - Wang, Dingdi

AU - Grant, Alexander

AU - He, Kai

AU - Weitz, Eric

AU - Nolan, Michael

AU - Gray, Kimberly A

AU - Notestein, Justin M

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N2 - Carbon dioxide hydrogenation to CO via the reverse water gas shift (RWGS) reaction is one route to integrate CO2 utilization into the chemical industry. TiO2 supported Cu catalysts are known to be active for RWGS, but Cu is shown here to behave differently on TiO2 nanotubes (TiNT) vs TiO2 nanoparticles (TiNP). Whereas nanoparticle supports give low rates that are hardly changed by added Cu, the nanotube supports yield much higher activity and three distinct behaviors as the Cu surface density increases. At low surface densities (0.3 Cu/nm2), active Cu-O-Ti sites are created that have low apparent activation energies. At high surface densities (6 Cu/nm2), Cu nanoparticles on TiNT are formed, and reaction barriers are lowered when both Cu and TiNT surfaces are accessible. At intermediate surface densities, metallic Cu domains are engulfed by a TiOx overlayer formed during H2 pretreatment, akin to those formed by classical strong metal support interactions (SMSI). These reduced layers are markedly more active for RWGS than the initial TiNT surfaces, but have similar activation barriers, which are higher than those for which both Cu and TiNP surfaces are exposed. These catalytic findings are supported by computational modeling, in situ IR, UV–vis, and X-ray absorption spectroscopies, and they provide insight into an important reaction for CO2 utilization.

AB - Carbon dioxide hydrogenation to CO via the reverse water gas shift (RWGS) reaction is one route to integrate CO2 utilization into the chemical industry. TiO2 supported Cu catalysts are known to be active for RWGS, but Cu is shown here to behave differently on TiO2 nanotubes (TiNT) vs TiO2 nanoparticles (TiNP). Whereas nanoparticle supports give low rates that are hardly changed by added Cu, the nanotube supports yield much higher activity and three distinct behaviors as the Cu surface density increases. At low surface densities (0.3 Cu/nm2), active Cu-O-Ti sites are created that have low apparent activation energies. At high surface densities (6 Cu/nm2), Cu nanoparticles on TiNT are formed, and reaction barriers are lowered when both Cu and TiNT surfaces are accessible. At intermediate surface densities, metallic Cu domains are engulfed by a TiOx overlayer formed during H2 pretreatment, akin to those formed by classical strong metal support interactions (SMSI). These reduced layers are markedly more active for RWGS than the initial TiNT surfaces, but have similar activation barriers, which are higher than those for which both Cu and TiNP surfaces are exposed. These catalytic findings are supported by computational modeling, in situ IR, UV–vis, and X-ray absorption spectroscopies, and they provide insight into an important reaction for CO2 utilization.

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KW - Spectroscopy

KW - Supported metals

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