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Title: Temperature-Dependent Evolution of the Oxidation States of Cobalt and Platinum in Co 1–x Pt x Clusters under H 2 and CO + H 2 Atmospheres

Abstract

Co1-xPtx clusters of 2.9-nm size with a range of atomically precise Pt/Co atomic ratios (x = 0, 0.25, 0.5, 0.75, 1) were synthesized using the mass-selected low-energy cluster beam deposition (LECBD) technique and soft-landed onto an amorphous alumina thin film prepared by atomic layer deposition (ALD). Utilizing ex situ X-ray photoemission spectroscopy (XPS), the oxidation state of the as-made clusters supported on Al2O3 was determined after both a 1-h-long exposure to air and aging for several weeks while exposed to air. Next, the aged duster samples were characterized by grazing-incidence X-ray absorption spectroscopy (GIXAS) and then pretreated with diluted hydrogen and further exposed to the mixture of diluted CO and H-2 up to 225 degrees C at atmospheric pressure, and the temperature-dependent evolutions of the particle size/shape and the oxidation states of the individual metal components within the dusters were monitored using in situ grazing-incidence small-angle X-ray scattering and X-ray absorption spectroscopy (GISAXS/GIXAS). The changes in the oxidation states of Co and Pt exhibited a nonlinear dependence on the Pt/Co atomic ratio of the dusters. For example, a low Pt/Co ratio (x <= 0.5) facilitates the formation of Co(OH)(2), whereas a high Pt/Co ratio (x = 0.75) stabilizes the Co3O4more » composition instead through the formation of a Co-Pt core-shell structure where the platinum shell inhibits the reduction of cobalt in the core of the Co1-xPtx alloy dusters. The obtained results indicate methods for optimizing the composition and structure of binary alloy clusters for catalysis.« less

Authors:
; ; ; ; ; ; ; ; ;
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
USDOE Office of Science - Office of Basic Energy Sciences - Materials Sciences and Engineering Division
OSTI Identifier:
1392497
DOE Contract Number:
AC02-06CH11357
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Physical Chemistry. C; Journal Volume: 120; Journal Issue: 38
Country of Publication:
United States
Language:
English

Citation Formats

Yang, Bing, Khadra, Ghassan, Tuaillon-Combes, Juliette, Tyo, Eric C., Pellin, Michael J., Reinhart, Benjamin, Seifert, Sönke, Chen, Xinqi, Dupuis, Veronique, and Vajda, Stefan. Temperature-Dependent Evolution of the Oxidation States of Cobalt and Platinum in Co 1–x Pt x Clusters under H 2 and CO + H 2 Atmospheres. United States: N. p., 2016. Web. doi:10.1021/acs.jpcc.6b06483.
Yang, Bing, Khadra, Ghassan, Tuaillon-Combes, Juliette, Tyo, Eric C., Pellin, Michael J., Reinhart, Benjamin, Seifert, Sönke, Chen, Xinqi, Dupuis, Veronique, & Vajda, Stefan. Temperature-Dependent Evolution of the Oxidation States of Cobalt and Platinum in Co 1–x Pt x Clusters under H 2 and CO + H 2 Atmospheres. United States. doi:10.1021/acs.jpcc.6b06483.
Yang, Bing, Khadra, Ghassan, Tuaillon-Combes, Juliette, Tyo, Eric C., Pellin, Michael J., Reinhart, Benjamin, Seifert, Sönke, Chen, Xinqi, Dupuis, Veronique, and Vajda, Stefan. Thu . "Temperature-Dependent Evolution of the Oxidation States of Cobalt and Platinum in Co 1–x Pt x Clusters under H 2 and CO + H 2 Atmospheres". United States. doi:10.1021/acs.jpcc.6b06483.
@article{osti_1392497,
title = {Temperature-Dependent Evolution of the Oxidation States of Cobalt and Platinum in Co 1–x Pt x Clusters under H 2 and CO + H 2 Atmospheres},
author = {Yang, Bing and Khadra, Ghassan and Tuaillon-Combes, Juliette and Tyo, Eric C. and Pellin, Michael J. and Reinhart, Benjamin and Seifert, Sönke and Chen, Xinqi and Dupuis, Veronique and Vajda, Stefan},
abstractNote = {Co1-xPtx clusters of 2.9-nm size with a range of atomically precise Pt/Co atomic ratios (x = 0, 0.25, 0.5, 0.75, 1) were synthesized using the mass-selected low-energy cluster beam deposition (LECBD) technique and soft-landed onto an amorphous alumina thin film prepared by atomic layer deposition (ALD). Utilizing ex situ X-ray photoemission spectroscopy (XPS), the oxidation state of the as-made clusters supported on Al2O3 was determined after both a 1-h-long exposure to air and aging for several weeks while exposed to air. Next, the aged duster samples were characterized by grazing-incidence X-ray absorption spectroscopy (GIXAS) and then pretreated with diluted hydrogen and further exposed to the mixture of diluted CO and H-2 up to 225 degrees C at atmospheric pressure, and the temperature-dependent evolutions of the particle size/shape and the oxidation states of the individual metal components within the dusters were monitored using in situ grazing-incidence small-angle X-ray scattering and X-ray absorption spectroscopy (GISAXS/GIXAS). The changes in the oxidation states of Co and Pt exhibited a nonlinear dependence on the Pt/Co atomic ratio of the dusters. For example, a low Pt/Co ratio (x <= 0.5) facilitates the formation of Co(OH)(2), whereas a high Pt/Co ratio (x = 0.75) stabilizes the Co3O4 composition instead through the formation of a Co-Pt core-shell structure where the platinum shell inhibits the reduction of cobalt in the core of the Co1-xPtx alloy dusters. The obtained results indicate methods for optimizing the composition and structure of binary alloy clusters for catalysis.},
doi = {10.1021/acs.jpcc.6b06483},
journal = {Journal of Physical Chemistry. C},
number = 38,
volume = 120,
place = {United States},
year = {Thu Sep 29 00:00:00 EDT 2016},
month = {Thu Sep 29 00:00:00 EDT 2016}
}
  • In this study, Co 1–xPt x clusters of 2.9-nm size with a range of atomically precise Pt/Co atomic ratios (x = 0, 0.25, 0.5, 0.75, 1) were synthesized using the mass-selected low-energy cluster beam deposition (LECBD) technique and soft-landed onto an amorphous alumina thin film prepared by atomic layer deposition (ALD). Utilizing ex situ X-ray photoemission spectroscopy (XPS), the oxidation state of the as-made clusters supported on Al 2O 3 was determined after both a 1-h-long exposure to air and aging for several weeks while exposed to air. Next, the aged cluster samples were characterized by grazing-incidence X-ray absorption spectroscopymore » (GIXAS) and then pretreated with diluted hydrogen and further exposed to the mixture of diluted CO and H 2 up to 225°C at atmospheric pressure, and the temperature-dependent evolutions of the particle size/shape and the oxidation states of the individual metal components within the clusters were monitored using in situ grazing-incidence small-angle X-ray scattering and X-ray absorption spectroscopy (GISAXS/GIXAS). The changes in the oxidation states of Co and Pt exhibited a nonlinear dependence on the Pt/Co atomic ratio of the clusters. For example, a low Pt/Co ratio (x ≤ 0.5) facilitates the formation of Co(OH) 2, whereas a high Pt/Co ratio (x = 0.75) stabilizes the Co 3O 4 composition instead through the formation of a Co–Pt core–shell structure where the platinum shell inhibits the reduction of cobalt in the core of the Co 1–xPt x alloy clusters. Finally, the obtained results indicate methods for optimizing the composition and structure of binary alloy clusters for catalysis.« less
  • The spiked-triangle cluster [Re{sub 2}Pt({mu}-H){sub 2}(CO){sub 9}[Re(CO){sub 5}]] B@ (1), which contains a HRe(CO){sub 5} molecule bound to the Pt vertex of a Re{sub 2}Pt triangle, reacts with methanolic NEt{sub 4}OH to give the red anion [Re{sub 2}Pt({mu}-H){sub 2}(CO){sub 9}[Re(CO){sub 5}]]{sup -} (2), whose structure has been determined by single-crystal X-ray analysis of its NEt{sub 4}{sup +} salt. NMR monitoring showed the intermediate formation of a carbomethoxy derivative 3, arising from the attack of OMe{sup -} on a carbonyl of the HRe(CO){sub 5} group. The deprotonation of 1 can be performed also by a base as weak as pyridine. Themore » anion 2 in solution is thermally unstable, and at room temperature it gives rise to complex mixtures. The main component has been identified, by X-ray analysis of its NEt{sub 4}{sup +} salt, as the anion [Re{sub 2}Pt({mu}-H){sub 2}(CO){sub 9}[HRe{sub 2}(CO){sub 9}]]RB{sup -} (4), containing a HRe{sub 2}(CO){sub 9}{sup +} complex bound to the Pt vertex of a Re{sub 2}Pt triangle, through a Re({mu}-H)Pt bond. The anions 2 and 4 are better obtained by treating [Re{sub 2}Pt({mu}-H){sub 2}(CO){sub 8}(COD)] (COD=1,5-cyclooctadiene) with [Re(CO){sub 5}]{sup -} or [HRe{sub 2}(CO){sub 9}]{sup -}, respectively, in the presence of CO. Experiments have been performed to clarify the origin of the [HRe{sub 2}(CO){sub 9}]{sup -} fragment bound to Pt in 4. The reaction between free [HRe(CO){sub 5}] and [Re(CO){sub 5}]{sup -} produces in high yields the anion [HRe{sub 2}(CO){sub 9}]{sup -}, but this one does not displace Re(CO){sub 5}{sup -} from 2. The reaction between [Re(CO){sub 5}]{sup -} and the complex 1 gives instantaneously the anion 2. No reaction occurs upon treatment of the anion 2 with [HRe(CO){sub 5}]. Variable-temperature NMR has revealed the occurrence in both the anions 3 and 4 of an intramolecular dynamic process equalizing the two hydrides bound to the Pt atom, with E{sub a}=70(1) and 74(7) kJ/mol, respectively.« less
  • The reaction of Ru[sub 4]Pt[sub 2](CO)[sub 18] with Ru[sub 4](CO)[sub 13]([mu]-H)[sub 2] at 97[degrees]C yielded the new decanuclear platinum-ruthenium carbonyl cluster complex Ru[sub 8]Pt[sub 2](CO)[sub 23]([mu][sub 3]-H)[sub 2] 1 (22%). In a similar manner the reaction of Ru[sub 4]Pt[sub 2](CO)[sub 18] with Ru[sub 3]Pt(CO)[sub 10](COD)([mu]-H)[sub 2], 2, in 25% yield. Both compounds were characterized by IR, [sup 1]H NMR, and single-crystal X-ray diffraction analyses, and both were bound to consist of similar edge-fused bioctahedral clusters with platinum atoms along the edge-sharing sites. There are strong metal-metal bonds between the apices of the adjacent octahedra. Both compounds are electron deficient, andmore » one of the apical-apical Ru-Ru bonds is unusually short, 2.580 (2) [Angstrom] in 1 and 2.593 (5) [Angstrom] in 2. The hydrides are triply bridging ligands, and these were located and refined crystallographically in 1. The reaction of 1 with 1,2-bis(diphenylphosphino)ethane, dppe, yielded the adduct Ru[sub 8]Pt[sub 2](CO)[sub 21]([mu][sub 3]-CO)[sub 2](dppe)([mu]-H)[sub 2], 3, in 12% yield, which was shown to consist of a face-shared bioctahedral cluster of seven ruthenium and two platinum atoms with a ruthenium spike containing the dppe ligand extending from one triruthenium face. Two novel dihapto-triply bridging carbonyl ligands were found to bridge to the ruthenium spike. 1 and 2 both react with CO at 25[degrees]C, but only the product obtained from the reaction of 2, Ru[sub 6]Pt[sub 3](CO)[sub 21]([mu]-CO)([mu][sub 3]-H)[sub 2], 4, (55% yields), could be fully characterized. It was shown to contain a cluster of nine metal atoms arranged into trinuclear layers of pure ruthenium and pure platinum. The two triply bridging hydride ligands were located and refined crystallographically. 23 refs., 4 figs., 13 tabs.« less
  • The reaction of Ru{sub 4}(CO){sub 13}({mu}-H){sub 2} (1) with Pt(COD){sub 2} at 25 C yielded four new platinum-ruthenium carbonyl cluster complexes Ru{sub 4}Pt(CO){sub 13}(COD)({mu}-H){sub 2} (2) (37%), Ru{sub 3}Pt(CO){sub 9}({mu}-CO)(COD)({mu}-H){sub 2} (3) (10%), Ru{sub 4}Pt{sub 2}-(CO){sub 11}(COD){sub 2}({mu}{sub 3}-H){sub 2} (4) (2.5%), and Ru{sub 5}Pt{sub 5}(CO){sub 18}(COD){sub 2}({mu}{sub 3}-H){sub 2} (5) (1%). All compounds were characterized by IR, {sup 1}H NMR, and single-crystal X-ray diffraction analyses. The cluster of compound 2 consists of a butterfly tetrahedron of four ruthenium atoms with one triangular face capped by a Pt(COD) grouping. Compound 3 consists of a cluster of three ruthenium atoms andmore » one platinum atom in a tetrahedral arrangement. Compound 4 consists of a tetrahedral cluster of four ruthenium atoms with two of the triangular faces capped by Pt(COD) groupings. The other two triangular faces have triply bridging hydride ligands. In the cluster of compound 5, the five ruthenium and four of the platinum atoms are arranged in the form of a face-shared bioctahedron. The shared face consists of three of the platinum atoms. The fifth platinum atom is a cap on one of the Ru{sub 2}Pt triangles. Two hydride ligands are believed to bridge metals of the triangular faces on the opposite ends of the bioctahedron.« less
  • The compound W{sub 2}(H){sub 2}(O{sup i}Pr){sub 4}({eta}{sup 2}-dmpe){sub 2} reacts in hydrocarbon solutions with CO, CO{sub 2}, and H{sub 2}O to give ({sup i}PrO){sub 4}WW({eta}{sup 2}-dmpe){sub 2}(CO), 1, ({eta}{sup 1}-O{sub 2}CH)({sup i}PrO){sub 4}WW({eta}{sup 2}-dmpe){sub 2}H, 2, and [H({eta}{sup 2}-dmpe){sub 2}WWO{sub 2}]{sub 2}({mu}-O), 3, respectively. Compound 1 reacts with H{sub 2}O in hydrocarbon solvents to give W{sub 2}(O){sub 4}({mu}-O)[W({eta}{sup 2}-dmpe){sub 2}(CO)]{sub 2}, 4. The compounds 1--4 contain unsupported W-W bonds between metal atoms in greatly different oxidation states. The new compounds have been characterized by NMR and infrared spectroscopy, and compounds 1 and 4, by single-crystal X-ray studies.