Zirconium oxide supported on Pd(100): Characterization by scanning tunneling microscopy and tunneling spectroscopy

Asakura, Kiyotaka; Iwasawa, Yasuhiro; Purnell, S. K.; Watson, Brian A.; Barteau, Mark A.; Gates, B. C.

doi:10.1007/bf00769154

Cited by 14 publications

(4 citation statements)

References 16 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…However, this effect is not consistent with our data; i.e., there is no concomitant deactivation, and Pd–Zr bonds are not observed. Furthermore, ZrO 2 decomposition has only been reported above 500 °C. , A second possibility is the NO-induced disruption and redispersion of the Pd particles over the support, leading to individual ions or small clusters on the ZrO 2 surface. The low Pd–Pd CN obtained at 120 °C and the detection of an additional interface/surface component [Pd–X] can be easily explained if Pd redispersion is considered.…”

Section: Discussionmentioning

confidence: 99%

“…The loss of Pd is disregarded due to the lack of changes in the overall XAFS signal (e.g., absorption edge jump). The hypothesis of encapsulation of Pd by ZrO 2 and subsequent Zr–Pd alloy formation is also disregarded, since no Pd–Zr bonds were observed via EXAFS and ZrO 2 is known to decompose only above 500 °C, which is significantly higher than our maximum reaction temperature. , Therefore, the disappearance of the Pd features from the XPS spectrum in Figure vii is assigned to the reduction of the cationic Pd species to metallic Pd. The fact that a lower Pd signal (no clear signal) is detected at the end of the reaction via XPS as compared to that measured before the reaction but after H 2 reduction is assigned to the decrease in the BE of the metallic Pd species present in this sample, which leads to an even stronger overlap between ZrO 2 and Pd photoelectron peaks.…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Evolution of the Structure and Chemical State of Pd Nanoparticles during the in Situ Catalytic Reduction of NO with H₂

et al. 2011

View full text Add to dashboard Cite

An in-depth understanding of the fundamental structure of catalysts during operation is indispensable for tailoring future efficient and selective catalysts. We report the evolution of the structure and oxidation state of ZrO(2)-supported Pd nanocatalysts (∼5 nm) during the in situ reduction of NO with H(2) using X-ray absorption fine-structure spectroscopy and X-ray photoelectron spectroscopy. Prior to the onset of the reaction (≤120 °C), a NO-induced redispersion of our initial metallic Pd nanoparticles over the ZrO(2) support was observed, and Pd(δ+) species were detected. This process parallels the high production of N(2)O observed at the onset of the reaction (>120 °C), while at higher temperatures (≥150 °C) the selectivity shifts mainly toward N(2) (∼80%). Concomitant with the onset of N(2) production, the Pd atoms aggregate again into large (6.5 nm) metallic Pd nanoparticles, which were found to constitute the active phase for the H(2)-reduction of NO. Throughout the entire reaction cycle, the formation and stabilization of PdO(x) was not detected. Our results highlight the importance of in situ reactivity studies to unravel the microscopic processes governing catalytic reactivity.

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Evolution of the Structure and Chemical State of Pd Nanoparticles during the in Situ Catalytic Reduction of NO with H₂

et al. 2011

View full text Add to dashboard Cite

show abstract

“…In fact, we found a PdO layer near the Zr02 particles in Zr02/Pd single crystal by STM experiments. 21 As a result, it is suggested that the S-Zr02 interacts with the surface Pd oxide layers. The known Pd oxide is PdO which has a tetragonal structure with Pd-0 and Pd-Pd distances of 0.202 and 0.342 nm,22 respectively.…”

Section: Discussionmentioning

confidence: 99%

Reversible structure transformation of zirconium dioxide on palladium black

Asakura¹,

Iwasawa²

1992

J. Phys. Chem.

View full text Add to dashboard Cite

The structure and behavior of Zr02 on Pd black were studied by means of extended X-ray absorption fine structure (EXAFS). The mmible structure change of ZrO2 with the reduction at 773 K and oxidation at 673 K was observed. The Zr-Zr distances on Zr02/Pd after oxidation at 673 K were determined to be 0.345 and 0.363 nm (named b-Zr02), while Zr02/Pd after reduction at 773 K showed the tetragonal ZrOz structure with a Z r Z r distance at 0.366 nm. The & structure is stable against the H2 reduction at 473 K. The &-Zr02 structure is suggested to be stabilized by the interface Pd oxide. IatrodtlctionThe structures of and catalysis by supported metal particles are affected by the interaction with inorganic oxide supports.'-3 Convcrsely, the surface structures of oxide supports should also vary under the influence of metal particles and undergo physical or chemical change! In many c~8es, however, the change in the surface structures of oxide supports are spectroscopically hidden by the large amounts of unchanged bulk component. Thus little information is available about the structural change of support surfacts. In this work we used Pd black (small Pd particle with a crystallite size of 16.3 nm) on which Zr02 was deposited. The Pd black has a large surface area of 25.5 m2/g and efficiently interacts with Zr02 resulting in a good dispersion of Zr02. In this system one can obtain fundamental information about the structure and behavior of deposited Zr02 layers on Pd surface during the oxidation, " , and thermal treatments. Catalysis by Zr02-supported noble metals has been extensively Unlike Nb20S and Ti02, ZrO2 is hardly reduced and not a socalled SMSI" support. Howwer, the modification of the catalysis of Zr02-supported metals has been attributed to the partially r e d u d Zro, species at the interface by ESR spectroscopy.6 The donation of electrons from Zr02 to Pt in Pt/Zr02 catalyst increased with an increase in the reduction temperature similar to the cases of Ti02 and Nb@S?*lo The surface structural chemistry of Zr02 at the metal-support interface is of interest in relation to the origin of metal-support interaction and catalysis of supported metal.To examine the structure of Zr02 overlayers on Pd black, we employed extended X-ray absorption fine structure (EXAFS)" spectroscopy, which provides direct information on the local structure around an X-ray absorbing atom. In the present study we found a reversible structural change of Zr02 on Pd during the oxidation-reduction cycle. Experimental SectionPd black was purchased from Nippon Engelhalt Co. (crystallite size = 16.3 nm). The surface area of untreated Pd black was 25.5 m2/g by the BET measurement. ZrCll was purchased from the Soekawa Co. The Pd black was impregnated with an ethanol solution of ZrC4. The loading was 7 wt 96, corresponding to the amount of one monolayer of Zr metal atoms. After dried at 373 K, the samples were oxidized at 773 K. Then they were treated under various conditions in U-shaped tubes equipped with air-tight EXAFS cells which were connected t...

show abstract

“…Photoactivation of adsorbed VOCl 3 was carried out by UV excitation of the chargetransfer absorption band of VOCl 3 at approximately 300-450 nm. After treatment in H 2 , the ZrO 2 formed non-wetting particles on the Pd, with a sharp Pd/ZrO 2 interface [113]. 4 was oxidized at 673 K. The sample was subsequently reduced by treatment in H 2 at 773 K. When the sample was treated in O 2 , the ZrO 2 appeared as a smooth, featureless overlayer of varying thickness wetting the Pd.…”

Section: Vanadium (V)mentioning

confidence: 99%

Supported Catalysts from Chemical Vapor Deposition and Related Techniques

Tada

Iwasawa

2008

Handbook of Heterogeneous Catalysis

View full text Add to dashboard Cite

The sections in this article are Chemical Vapor Deposition ( CVD ) Technique CVD Precursors and Equipment CVD Catalysts Gold ( Au ) Cobalt ( Co ) Chromium ( Cr ) Copper ( Cu ) Iron ( Fe ) Gallium ( Ga ) Molybdenum ( Mo ) A Mo Carbonyls B Mo Cl 5 C Allylmolybdenum D Mo O 3 Vapor Niobium ( Nb ) Nickel ( Ni ) Osmium ( Os ) Palladium ( Pd ) Films and Particles Pd /Zeolites Platinum ( Pt ) Rhenium ( Re ) Rhodium ( Rh ) Ruthenium ( Ru ) SiO 2 Tin ( Sn ) Titanium ( Ti ) Vanadium ( V ) Tungsten ( W ) Zirconium ( Zr ) Bimetals Mixed Metal Oxides and Sulfides CVD ‐Related Techniques Concluding Remarks

show abstract

Zirconium oxide supported on Pd(100): Characterization by scanning tunneling microscopy and tunneling spectroscopy

Cited by 14 publications

References 16 publications

Evolution of the Structure and Chemical State of Pd Nanoparticles during the in Situ Catalytic Reduction of NO with H₂

Evolution of the Structure and Chemical State of Pd Nanoparticles during the in Situ Catalytic Reduction of NO with H₂

Reversible structure transformation of zirconium dioxide on palladium black

Supported Catalysts from Chemical Vapor Deposition and Related Techniques

Contact Info

Product

Resources

About

Zirconium oxide supported on Pd(100): Characterization by scanning tunneling microscopy and tunneling spectroscopy

Cited by 14 publications

References 16 publications

Evolution of the Structure and Chemical State of Pd Nanoparticles during the in Situ Catalytic Reduction of NO with H2

Evolution of the Structure and Chemical State of Pd Nanoparticles during the in Situ Catalytic Reduction of NO with H2

Reversible structure transformation of zirconium dioxide on palladium black

Supported Catalysts from Chemical Vapor Deposition and Related Techniques

Contact Info

Product

Resources

About

Evolution of the Structure and Chemical State of Pd Nanoparticles during the in Situ Catalytic Reduction of NO with H₂

Evolution of the Structure and Chemical State of Pd Nanoparticles during the in Situ Catalytic Reduction of NO with H₂