Argonne National Lab. (ANL), Argonne, IL (United States). Materials Science Division
University Lyon & CNRS, Lyon (France). Institut Lumiere Matiere
Argonne National Lab. (ANL), Argonne, IL (United States). X-ray Science Division
Northwestern Univ., Evanston, IL (United States). Department of Mechanical Engineering
Argonne National Lab. (ANL), Argonne, IL (United States). Materials Science Division and Nanoscience and Technology Division; Yale Univ., New Haven, CT (United States). Department of Chemical and Environmental Engineering; Univ. of Chicago, IL (United States). Institute for Molecular Engineering
In this study, 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 cluster 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 H2 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 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 clusters. Finally, the obtained results indicate methods for optimizing the composition and structure of binary alloy clusters for catalysis.
Yang, Bing, et al. "Temperature-Dependent Evolution of the Oxidation States of Cobalt and Platinum in Co<sub>1–<i>x</i></sub>Pt<sub><i>x</i></sub> Clusters under H<sub>2</sub> and CO + H<sub>2</sub> Atmospheres." Journal of Physical Chemistry. C, vol. 120, no. 38, Aug. 2016. https://doi.org/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 (2016). Temperature-Dependent Evolution of the Oxidation States of Cobalt and Platinum in Co<sub>1–<i>x</i></sub>Pt<sub><i>x</i></sub> Clusters under H<sub>2</sub> and CO + H<sub>2</sub> Atmospheres. Journal of Physical Chemistry. C, 120(38). https://doi.org/10.1021/acs.jpcc.6b06483
Yang, Bing, Khadra, Ghassan, Tuaillon-Combes, Juliette, et al., "Temperature-Dependent Evolution of the Oxidation States of Cobalt and Platinum in Co<sub>1–<i>x</i></sub>Pt<sub><i>x</i></sub> Clusters under H<sub>2</sub> and CO + H<sub>2</sub> Atmospheres," Journal of Physical Chemistry. C 120, no. 38 (2016), https://doi.org/10.1021/acs.jpcc.6b06483
@article{osti_1352595,
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},
title = {Temperature-Dependent Evolution of the Oxidation States of Cobalt and Platinum in Co<sub>1–<i>x</i></sub>Pt<sub><i>x</i></sub> Clusters under H<sub>2</sub> and CO + H<sub>2</sub> Atmospheres},
annote = {In this study, 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 cluster 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 H2 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 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 clusters. Finally, the obtained results indicate methods for optimizing the composition and structure of binary alloy clusters for catalysis.},
doi = {10.1021/acs.jpcc.6b06483},
url = {https://www.osti.gov/biblio/1352595},
journal = {Journal of Physical Chemistry. C},
issn = {ISSN 1932-7447},
number = {38},
volume = {120},
place = {United States},
publisher = {American Chemical Society},
year = {2016},
month = {08}}
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, Vol. 649, Issue 1https://doi.org/10.1016/j.nima.2010.12.172