TY - JOUR
T1 - Probing Molecular-Scale Catalytic Interactions between Oxygen and Cobalt Phthalocyanine Using Tip-Enhanced Raman Spectroscopy
AU - Nguyen, Duc
AU - Kang, Gyeongwon
AU - Chiang, Naihao
AU - Chen, Xu
AU - Seideman, Tamar
AU - Hersam, Mark C.
AU - Schatz, George C.
AU - Van Duyne, Richard P.
N1 - Funding Information:
D.N., N.C, G.C.S, and R.P.V.D. acknowledge support from the National Science Foundation Center for Chemical Innovation dedicated to Chemistry at the Space-Time Limit (CaSTL) Grant CHE-1414466. D.N., G.K., X.C., G.C.S, and R.P.V.D. acknowledge support from the Air Force Office of Scientific Research MURI (FA9550-14-1-0003). G.K. and G.C.S. acknowledge support from Northwestern University Information Technology (NUIT) team and the Center for Nanoscale Materials (CNM) at Argonne National Laboratory for the computational resources. N.C., T.S., M.C.H., and R.P.V.D. acknowledge support from the National Science Foundation Materials Research Science and Engineering Center (NSF Grant DMR-1121262).
Publisher Copyright:
© 2018 American Chemical Society.
PY - 2018/5/9
Y1 - 2018/5/9
N2 - Ultrahigh vacuum tip-enhanced Raman spectroscopy (UHV-TERS) is used to investigate adsorption of molecular oxygen (O2) 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 O2/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 18O-18O stretching frequency at 1151 cm-1 for O2/CoPc/Ag(111), and Co-16O and Co-18O vibrational frequencies at 661 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. This study establishes UHV-TERS as a chemically sensitive tool for probing catalytic systems at the molecular scale.
AB - Ultrahigh vacuum tip-enhanced Raman spectroscopy (UHV-TERS) is used to investigate adsorption of molecular oxygen (O2) 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 O2/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 18O-18O stretching frequency at 1151 cm-1 for O2/CoPc/Ag(111), and Co-16O and Co-18O vibrational frequencies at 661 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. This study establishes UHV-TERS as a chemically sensitive tool for probing catalytic systems at the molecular scale.
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U2 - 10.1021/jacs.8b01154
DO - 10.1021/jacs.8b01154
M3 - Article
C2 - 29683321
AN - SCOPUS:85046139969
VL - 140
SP - 5948
EP - 5954
JO - Journal of the American Chemical Society
JF - Journal of the American Chemical Society
SN - 0002-7863
IS - 18
ER -