Regular arrays of palladium and palladium-gold clusters supported on ultrathin alumina films: stability under oxygen

Sitja, Georges; Marsault, M.; Fré, N. A.; De, Nerea; Leroy, R. C.; Se, Naomi; Moal, Séverine Le; Henry, Claude R.

doi:10.1504/ijnt.2012.045338

Cited by 6 publications

(4 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Because of the little size of the clusters, the size distribution seems wide in the STM pictures but GISAXS studies shows that actually the size distribution is very narrow. The particle organization is stable up to 600 K and under the low pressures of CO and O 2 , which are used in the CO oxidation experiments. , The density of clusters being 6.5 × 10 12 cm –2 , the average number of clusters is determined in dividing the number of deposited atoms issued from a calibrated Knudsen cell by the density of clusters. The clusters grow in the (111) epitaxy on the alumina ultrathin film.…”

Section: Growth and Characterization Of The Arrays Of Pd Clustersmentioning

confidence: 99%

Molecular Beam Study of the Oxidation of Carbon Monoxide on a Regular Array of Palladium Clusters on Alumina

Sitja

Henry

2016

J. Phys. Chem. C

Self Cite

View full text Add to dashboard Cite

For the first time, CO oxidation has been studied by molecular beam methods on a regular array of metal clusters with a very narrow size distribution. The use of a regular array of clusters offers the possibility to quantify the effect of the reverse spillover of CO, which increases the flux of CO adsorbing on the metal clusters. The reverse spillover of CO is studied on a hexagonal array of Pd clusters grown on an alumina ultrathin film on Ni3Al(111). Comparing the adsorption rate of CO with an analytical model describing exactly the CO adsorption on the supported cluster array, the adsorption probability and the difference between the adsorption energy and the diffusion energy of a CO molecule on the alumina substrate are determined. The turnover frequency (TOF) for the CO oxidation reaction is measured as a function of temperature. After correction from the reverse spillover effect, the TOF measured on the Pd clusters with an average size of 181 atoms is compared with TOF values previously obtained on Pd(111). The Pd clusters clearly show an increased catalytic activity at low temperature in comparison with Pd extended surfaces. This enhancement is explained by the low value of the adsorption energy of CO on the Pd clusters that moves the CO poisoning domain to lower temperatures.

show abstract

Section: Growth and Characterization Of The Arrays Of Pd Clustersmentioning

confidence: 99%

Molecular Beam Study of the Oxidation of Carbon Monoxide on a Regular Array of Palladium Clusters on Alumina

Sitja

Henry

2016

J. Phys. Chem. C

Self Cite

View full text Add to dashboard Cite

show abstract

“…AuPd clusters have been studied theoretically and experimentally as a model for heterogeneous catalysis and due to their catalytic properties. − A majority of these studies deal with experimental synthesis and characterization of AuPd nanoclusters. − In the group of Henry, − arrays of AuPd were synthesized on ultrathin films of alumina, ranging in size from a few atoms up to 400 atoms. These nanoclusters are tunable in size and composition and self-organize on the alumina substrates.…”

Section: Introductionmentioning

confidence: 99%

Combining Deep Learning Neural Networks with Genetic Algorithms to Map Nanocluster Configuration Spaces with Quantum Accuracy at Low Computational Cost

von der Heyde,

Malone,

Zaman

et al. 2023

J. Chem. Inf. Model.

View full text Add to dashboard Cite

The configuration spaces for bimetallic AuPd nanoclusters of various sizes are explored efficiently and analyzed accurately by combining genetic algorithms with neural networks trained on density functional theory. The methodology demonstrated herein provides an optimizable solution to the problem of searching vast configuration spaces with quantum accuracy in a way that is computationally practical. We implement a machine learning algorithm which learns the density functional theory potential with increasing performance while simultaneously generating and relaxing structures within the system's global configuration space unbiasedly. As a result, the algorithm naturally converges onto the system's energy minima while mapping the configuration space as a function of energy. The algorithm's simple design applies not only to nanocluster configurations, as demonstrated, but to bulk, substrate, and adsorption sites as well, and it is designed to scale. To demonstrate its computational efficiency, we work with AuPd nanoclusters of sizes 15, 20, and 25 atoms. Results focus primarily on evaluating the algorithm's performance; however, several physical insights into possible configurations for these nanoclusters naturally emerge as well, such as geometric Au surface segregation and stoichiometric Au minimization as a function of stability.

show abstract

“…From STM and GISAXS studies, , the organization of the PdAu cluster lattice is stable for clusters from a few to 400 atoms. The lattices are stable at temperature up to 600 K and under oxygen atmosphere (10 –6 mbar) and under CO atmosphere …”

Section: Introductionmentioning

confidence: 99%

“…From STM and GISAXS studies, 26,27 the organization of the PdAu cluster lattice is stable for clusters from a few to 400 atoms. The lattices are stable at temperature up to 600 K 26 and under oxygen atmosphere (10 −6 mbar) 28 and under CO atmosphere. 29 In this paper we study the adsorption of CO on PdAu clusters having the same size and variable chemical compositions.…”

Section: Introductionmentioning

confidence: 99%

Molecular Beam Study of the CO Adsorption on a Regular Array of PdAu Clusters on Alumina

Sitja

Henry

2018

J. Phys. Chem. C

Self Cite

View full text Add to dashboard Cite

The adsorption kinetics of CO on PdAu bimetallic clusters, containing 140 ± 12 atoms and a composition varying between 55% and 100% of Pd atoms, is investigated by a pulsed molecular beam method (MBRS). The clusters are grown on a nanostructured ultrathin film of alumina on Ni3Al(111), playing the role of a template which gives a hexagonal array of bimetallic clusters having a sharp size distribution and a uniform composition. The surface concentration calculated, assuming segregation of gold to the surface, varies between 0 and 90% of Au atoms. From the adsorption–desorption kinetics of CO, the lifetime of CO is measured at various temperatures. At low coverage, plotting the CO lifetime in an Arrhenius diagram, one obtains the adsorption energy of CO. When the surface concentration of Au increases, the adsorption energy of CO on the PdAu clusters decreases. This evolution of the adsorption energy is discussed, from previous studies, in terms of ligand and ensemble effects. We find that the ensemble effect plays a dominant role in the observed decrease of the adsorption energy of CO.

show abstract

Regular arrays of palladium and palladium-gold clusters supported on ultrathin alumina films: stability under oxygen

Cited by 6 publications

References 0 publications

Molecular Beam Study of the Oxidation of Carbon Monoxide on a Regular Array of Palladium Clusters on Alumina

Molecular Beam Study of the Oxidation of Carbon Monoxide on a Regular Array of Palladium Clusters on Alumina

Combining Deep Learning Neural Networks with Genetic Algorithms to Map Nanocluster Configuration Spaces with Quantum Accuracy at Low Computational Cost

Molecular Beam Study of the CO Adsorption on a Regular Array of PdAu Clusters on Alumina

Contact Info

Product

Resources

About