Probing Molecular-Scale Catalytic Interactions between Oxygen and Cobalt Phthalocyanine Using Tip-Enhanced Raman Spectroscopy.

Author(s) Nguyen, D.; Kang, G.; Chiang, N.; Chen, X.; Seideman, T.; Hersam, M.C.; Schatz, G.C.; Van Duyne, R.P.
Journal J Am Chem Soc
Date Published 2018 Apr 23
Abstract

Ultrahigh vacuum tip-enhanced Raman spectroscopy (UHV-TERS) is used to investigate adsorption of molecular oxygen (O) on cobalt (II) phthalocyanine (CoPc) supported on Ag(111) single crystal surfaces, which is the initial step for the oxygen reduction reaction (ORR) using metal Pc catalysts. Two adsorption configurations are primarily observed, assigned as O/CoPc/Ag(111) and O/CoPc/Ag(111) based on scanning tunneling microscopy (STM) imaging, TERS, isotopologue substitution, and density functional theory (DFT) calculations. Distinct vibrational features are observed for different adsorption configurations such as the O-O stretching frequency at 1151 cm for O/CoPc/Ag(111), and Co-O and Co-O vibrational frequencies at 661 cm and 623 cm, 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. This study establishes UHV-TERS as a chemically sensitive tool for probing catalytic systems at the molecular-scale.

DOI 10.1021/jacs.8b01154
ISSN 1520-5126
Citation Nguyen D, Kang G, Chiang N, Chen X, Seideman T, Hersam MC, et al. Probing Molecular-Scale Catalytic Interactions between Oxygen and Cobalt Phthalocyanine Using Tip-Enhanced Raman Spectroscopy. J Am Chem Soc. 2018.

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