Molecular-scale interrogation of catalytic interactions between oxygen and cobalt phthalocyanine using ultrahigh vacuum tip-enhanced raman spectroscopy

Nguyen, Duc

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https://hdl.handle.net/2142/100442 Copy

Description

Title

Molecular-scale interrogation of catalytic interactions between oxygen and cobalt phthalocyanine using ultrahigh vacuum tip-enhanced raman spectroscopy

Author(s)

Nguyen, Duc

Contributor(s)

• Van Duyne, Richard P.
• Schatz, George C.
• Kang, Gyeongwon

Issue Date

2018-06-22

Keyword(s)

Vibrational structure/frequencies

Abstract

Ultrahigh vacuum tip-enhanced Raman spectroscopy (UHV-TERS) is a powerful method combining the rich chemical information of vibrational spectroscopy with the ultrahigh spatial resolution of scanning tunneling microscopy (STM). However, despite of its potential, there is a lack of studies demonstrating the capability of UHV-TERS in investigating chemical reactions and molecular adsorptions under controlled environment. Herein, we use UHV-TERS to investigate adsorption of oxygen (O2) with cobalt (II) phthalocyanine (CoPc) supported on Ag(111) single crystal surfaces under highly controlled environment, which is the initial step for the oxygen reduction reaction (ORR) using metal Pc catalysts. Two adsorption configurations are primarily observed, assigned as O2/CoPc/Ag(111) and O/CoPc/Ag(111) based on STM imaging, TERS, isotopologue substitution, and density functional theory (DFT) calculations. Distinct vibrational features are observed for different adsorption configurations such as the 18O-18O stretching frequency at 1151 cm−1 for O2/CoPc/Ag(111), and Co-16O and Co-18O vibrational frequencies at 661 cm−1 and 623 cm−1 , respectively, for O/CoPc/Ag(111). DFT calculations show vibrational mode coupling of O-O and Co-O vibrations to the Pc ring, resulting in different symmetries of oxygen-related normal modes for different isotopes. This study establishes UHV-TERS as a chemically sensitive tool for probing catalytic systems at the molecular-scale.

Publisher

International Symposium on Molecular Spectroscopy

Type of Resource

text

Language

eng

Permalink

http://hdl.handle.net/2142/100442

DOI

10.15278/isms.2018.FA06

Copyright and License Information

Copyright 2018 Duc Nguyen

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