Title: Identifying site-dependent reactivity in oxidation reactions on single Pt particles

Abstract

Catalytic nanoparticles are heterogeneous in their nature and even within the simplest particle various surface sites exist and influence the catalytic reactivity. Thus, detailed chemical information at the nanoscale is essential for understanding how surface properties and reaction conditions direct the reactivity of different surface sites of catalytic nanoparticles. In this work, hydroxyl-functionalized Nheterocyclic carbene molecules (NHCs) were anchored to the surface of Pt particles and utilized as chemical markers to detect reactivity variations between different surface sites under liquid and gas phase oxidizing conditions. Differences in the chemical reactivity of surface-anchored NHCs were identified using synchrotron-radiation-based infrared nanospectroscopy with a spatial resolution of 20 nanometers. By conducting IR nanospectroscopy measurements, along with complementary spatially averaged IR and X-ray spectroscopy measurements, we identified that enhanced reactivity occurred on the particles' periphery under both gas and liquid phase oxidizing conditions. Under gas phase reaction conditions the NHCs' hydroxyl functional groups underwent preferential oxidization to the acid along the perimeter of the particle. Exposure of the sample to harsher, liquid phase oxidizing conditions induced modification of the NHCs, which was mostly identified at the particle's periphery. Analysis of X-ray absorption spectroscopy measurements revealed that exposure of the sample to oxidizing conditions inducedmore » aromatization of the NHCs, presumably due to oxidative dehydrogenation reaction, along with reorientation of the NHCs from perpendicular to parallel to the Pt surface. These results, based on single particle measurements, demonstrate the high reactivity of surface sites that are located at the nanoparticle's periphery and the influence of reaction conditions on site-dependent reactivity.« less

Authors:

Dery, Shahar ^[1]; Kim, Suhong  ^[2];

• Search DOE PAGES for author "Kim, Suhong"
• Search DOE PAGES for ORCID "0000-0002-2315-6636"

Haddad, David ^[1]; Cossaro, Albano  ^[3];

• Search DOE PAGES for author "Cossaro, Albano"
• Search DOE PAGES for ORCID "0000-0002-8429-1727"

Verdini, Alberto  ^[3];

• Search DOE PAGES for author "Verdini, Alberto"
• Search DOE PAGES for ORCID "0000-0001-8880-2080"

Floreano, Luca  ^[3];

• Search DOE PAGES for author "Floreano, Luca"
• Search DOE PAGES for ORCID "0000-0002-3654-3408"

Toste, F. Dean  ^[2];

• Search DOE PAGES for author "Toste, F. Dean"
• Search DOE PAGES for ORCID "0000-0001-8018-2198"

Gross, Elad  ^[1]

• Search DOE PAGES for author "Gross, Elad"
• Search DOE PAGES for ORCID "0000-0002-8330-7299"

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+ Show Author Affiliations

1. Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904, Israel, The Center for Nanoscience and Nanotechnology
2. Department of Chemistry, University of California, Berkeley, USA
3. CNR-IOM, Laboratorio Nazionale TASC, Trieste 34012, Italy

Publication Date:

Tue Jul 03 00:00:00 EDT 2018

Research Org.:

Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States). Advanced Light Source (ALS)

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES). Chemical Sciences, Geosciences & Biosciences Division; United States-Israel Binational Science Foundation (BSF); Ministry of Energy; Rudin Fellowship

OSTI Identifier:

1459728

Alternate Identifier(s):

OSTI ID: 1624962

Grant/Contract Number:  

AC02-05CH11231; 2016344

Resource Type:

Published Article

Journal Name:

Chemical Science

Additional Journal Information:

Journal Name: Chemical Science Journal Volume: 9 Journal Issue: 31; Journal ID: ISSN 2041-6520

Publisher:

Royal Society of Chemistry

Country of Publication:

United Kingdom

Language:

English

Subject:

77 NANOSCIENCE AND NANOTECHNOLOGY; 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; Chemistry