Nanosizing Intermetallic Compounds Onto Carbon Nanotubes: Active and Selective Hydrogenation Catalysts

Shao, Lei; Zhang, Wei; Armbrüster, Marc; Teschner, Detre; Girgsdies, Frank; Zhang, Bingsen; Timpe, Olaf; Friedrich, Matthias; Schlögl, Robert; Su, Dang Sheng

doi:10.1002/anie.201008013

Cited by 139 publications

(94 citation statements)

References 36 publications

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“…7−9 Developing catalysts using intermetallic compounds could also benefit from their structural stability arising from highly favorable formation enthalpies. It has been shown that intermetallic compounds could maintain their surface structure under reaction conditions, 10 whereas the surface composition and structure of alloys usually change under different reaction environments. 11 Combined, these two features, unique electronic structure and high stability, potentially circumvent problems with traditional, supported multimetal/alloy catalysts, such as chemical heterogeneity of particles (which is detrimental to selectivity), broad distributions of active sites, surface segregation, and the formation of carbides or hydrides.…”

Section: * S Supporting Informationmentioning

confidence: 99%

Intermetallic NaAu₂ as a Heterogeneous Catalyst for Low-Temperature CO Oxidation

Xiao¹,

Wang

Maligal‐Ganesh³

et al. 2013

J. Am. Chem. Soc.

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The enhanced stability and modified electronic structure of intermetallic compounds provide discovery of superior catalysts for chemical conversions with high activity, selectivity, and stability. We find that the intermetallic NaAu 2 is an active catalyst for CO oxidation at low temperatures. From density functional theory calculations, a reaction mechanism is suggested to explain the observed low reaction barrier of CO oxidation by NaAu 2 , in which a CO molecule reacts directly with an adsorbed O 2 to form an OOCO* intermediate. The presence of surface Na increases the binding energy of O 2 and decreases the energy barrier of the transition states. KeywordsMaterials Science and Engineering, Ames Laboratory, chemical conversions, enhanced stability, heterogeneous catalyst, low temperatures, reaction barriers, reaction mechanism, superior catalysts, electronic structure, gold, oxygen, sodium, alloy, carbon monoxide ABSTRACT: The enhanced stability and modified electronic structure of intermetallic compounds provide discovery of superior catalysts for chemical conversions with high activity, selectivity, and stability. We find that the intermetallic NaAu 2 is an active catalyst for CO oxidation at low temperatures. From density functional theory calculations, a reaction mechanism is suggested to explain the observed low reaction barrier of CO oxidation by NaAu 2 , in which a CO molecule reacts directly with an adsorbed O 2 to form an OOCO* intermediate. The presence of surface Na increases the binding energy of O 2 and decreases the energy barrier of the transition states.

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Section: * S Supporting Informationmentioning

confidence: 99%

Intermetallic NaAu₂ as a Heterogeneous Catalyst for Low-Temperature CO Oxidation

Xiao¹,

Wang

Maligal‐Ganesh³

et al. 2013

J. Am. Chem. Soc.

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“…Active and selective Pd 2 Ga intermetallic compounds supported on CNT were used in alkynes hydrogenation. Ordered structures form high barriers for subsurface chemistry and prevent large ensembles on the Pd surface 19 . Also, surface inspection of intermetallic PdGa 1 1 1 ( ) reveals a smooth surface with an (1 × 1) unit cell where no segregation occurs.…”

Section: Introductionmentioning

confidence: 99%

The Electronic Structure and Bonding of Acetylene on PdGa(110)

et al. 2015

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We have studied the adsorption of acetylene on the PdGa(110) surface by Density Functional Theory (DFT) calculation. Our results predict the Hollow site is the most stable location for the adsorbate. In this site, both Pd and Ga atoms interact with acetylene. This molecule is bonded with the C-C bond almost parallel to the surface. A small tilt angle of 4.1° is computed. The C atoms present a rehybridization from sp sp 2 . This rehybridization is also present in Bridge site but it is not present in the Top configuration, where the C-C-H bond angle is about 160°. We computed the total Density of State (DOS) for the system and also the projection on Pd, Ga, C and H atoms. These plots show a shift to lower energies on C and H projected states, which is an indication of stabilization after adsorption. At the same time, a reduction in the density for Pd atom directly bonded to C atom. The Crystal Orbital Overlap Population (COOP) curves show an increase in the C-C overlap population (OP) after adsorption; while, the C 2 H 2 rehybridizes to a near sp 2 geometry. The acetylene withdraws charge from the surface indicating a donation-adsorption mechanism. The formation of Pd-C and Ga-C bonds and a decrease in OP for Pd-Pd and Pd-Ga bonds are detected. We also found, in the Hollow site, a reduction in the C-C bond stretching vibrational frequency. This is an indication of the significant distortion in the adsorbed molecule. We have also found that the C-C bond breaking is unfavorable and that the semihydrogenation is 2.27 eV more stable than C 2 H 2 +H 2 in the gas phase.

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“…Figure 35 is a typical example how the structure and composition of a bimetallic system are accessed by a combination of STEM with EDS, element mapping ( Figure 35a), and line scan (Figure 35b). 273 For the studied Pd−Ga catalyst used for alkyne-selective hydrogenation, STEM-EDX analysis and elemental maps reveal a homogeneous composition of Pd and Ga of an atomic ration of 2:1; that is, the bimetallic particle is Pd 2 Ga (Figure 35a). A TEM-EDX line scan shows that the composition of Pd 2 Ga particles remains unchanged after reaction (Figure 35b).…”

Section: Structure and Dynamics Of Bimetallic Particlesmentioning

confidence: 99%

Electron Microscopy of Solid Catalysts—Transforming from a Challenge to a Toolbox

2015

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Nanosizing Intermetallic Compounds Onto Carbon Nanotubes: Active and Selective Hydrogenation Catalysts

Cited by 139 publications

References 36 publications

Intermetallic NaAu₂ as a Heterogeneous Catalyst for Low-Temperature CO Oxidation

Intermetallic NaAu₂ as a Heterogeneous Catalyst for Low-Temperature CO Oxidation

The Electronic Structure and Bonding of Acetylene on PdGa(110)

Electron Microscopy of Solid Catalysts—Transforming from a Challenge to a Toolbox

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Nanosizing Intermetallic Compounds Onto Carbon Nanotubes: Active and Selective Hydrogenation Catalysts

Cited by 139 publications

References 36 publications

Intermetallic NaAu2 as a Heterogeneous Catalyst for Low-Temperature CO Oxidation

Intermetallic NaAu2 as a Heterogeneous Catalyst for Low-Temperature CO Oxidation

The Electronic Structure and Bonding of Acetylene on PdGa(110)

Electron Microscopy of Solid Catalysts—Transforming from a Challenge to a Toolbox

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Intermetallic NaAu₂ as a Heterogeneous Catalyst for Low-Temperature CO Oxidation

Intermetallic NaAu₂ as a Heterogeneous Catalyst for Low-Temperature CO Oxidation