Subscriber access provided by UNIV AUTONOMA DE COAHUILA UADEC
C: Surfaces, Interfaces, Porous Materials, and Catalysis
Electronic Metal-Support Interactions between Pt Nanoparticles and Co(OH) Flakes for CO Oxidation 2
Xueyang Song, Li Huang, Wenxue He, Chengyong Liu, Fengchun Hu, Yong Jiang, Zhihu Sun, and Shiqiang Wei J. Phys. Chem. C, Just Accepted Manuscript • DOI: 10.1021/acs.jpcc.8b12518 • Publication Date (Web): 08 Apr 2019 Downloaded from http://pubs.acs.org on April 8, 2019
Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.
is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.
Page 1 of 23 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
The Journal of Physical Chemistry
Electronic Metal-Support Interactions between Pt Nanoparticles and Co(OH)2 Flakes for CO Oxidation Xueyang Song, Li Huang, Wenxue He, Chengyong Liu, Fengchun Hu, Yong Jiang, Zhihu Sun*, and Shiqiang Wei National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei 230029, P. R. China. Abstract: Electronic metal-support interaction (EMSI) has opened a new way to tailor the electronic and catalytic properties of supported catalysts. Herein, we demonstrate the EMSI between Pt nanoparticles and Co(OH)2 flakes grown on SiO2, and show its beneficial effect on enhancing the CO oxidation activity. The EMSI characteristics of the Pt-Co(OH)2/SiO2 catalyst are identified by in-situ X-ray absorption fine structure (XAFS), in-situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and transmission electron microscopy. Quantitative XAFS analysis reveals the presence of metallic-like Pt−Co bonds. The formation Pt−Co intermetallic bonds allows for Co electrons donation to Pt, leading to the negative charging of the Pt atoms as evidenced by reduced Pt 2p-to-5d electron transition intensity detected by XAFS and the emergence of a CO adsorption band at 2063 cm-1 in DRIFTS. The significance of the EMSI is manifested by comparing the CO oxidation activity over the Pt-Co(OH)2/SiO2 and Pt/SiO2 catalysts with similar Pt loadings. Pt-Co(OH)2/SiO2 is superior to Pt/SiO2 in both the apparent activation energy (19 vs. 64 kJ/mol) and the turnover frequency (0.03 vs. 0.003 s-1 at 37 C). The enhanced activity is attributed to the negative charging of Pt which downshifts the d-band center and reduces the CO adsorption strength.
* Corresponding author. E-mail:
[email protected].
ACS Paragon Plus Environment
The Journal of Physical Chemistry 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Introduction Metal-support interactions play a key role for the catalytic performance of supported metal catalysts.1-4 Very recently, a new type of metal-support interactions, the electronic metal-support interaction (EMSI),5 has attracted increasing attention ever since it was first coined by Campbell5 in 2012 to understand the excellent activity of Pt/CeO2 catalysts for dissociating the O-H bonds in water.6 In contrast to the classical strong metal-support interaction (SMSI),7-9 the encapsulation of the metal by an overlayer of the support does not occur in the EMSI phenomenon, so that the active sites are still exposed to adsorbates. The EMSI effect could be used to tailor the electronic and chemical properties of the metal nanoparticles, through chemical bonding and charge transfer across the metal-support interface. Due to the ability to enhance the activity, selectivity and stability of the supported catalysts, the studies on EMSI have been performed extensively and theoretical understanding of this phenomenon has been proposed.10 Maximizing the EMSI effect to optimize the catalytic performance remains an active subject of research in catalysis. The key feature of EMSI is the charge transfer between the metal and support, which provides a direct way to modulate the d electronic states of supported catalysts. Depending on the combination of metal and support, the direction and the magnitude of the charge transfer could be varied. For the Pt nanoparticles of 13.5 nm supported on CeO2, the charge is transferred from Pt to CeO2 via the strong Pt-O chemical bonds, leading to the formation of Pt+ (0.011) where the maximum is reached for Pt particles composed of 30−70 atoms.11 This electronic perturbation of Pt is the origin of the activity for the water-gas shift reaction.6 The EMSI effect is also used to enhance the catalytic activity in the low-temperature oxidation of formaldehyde for single-atom Ag+ (0
