Mechanistic Insights on the Low-Temperature Oxidation of CO Catalyzed by Isolated Co Ions in N-Doped Carbon

Colby A. Whitcomb; Anna Sviripa; Michael I. Schapowal; Konstantin Mamedov; Raymond R. Unocic; Christopher Paolucci; Robert J. Davis

doi:10.1021/acscatal.2c04380

Mechanistic Insights on the Low-Temperature Oxidation of CO Catalyzed by Isolated Co Ions in N-Doped Carbon

Colby A. Whitcomb, Anna Sviripa, Michael I. Schapowal, Konstantin Mamedov, Raymond R. Unocic, Christopher Paolucci, Robert J. Davis

Materials MicroAnalysis

Research output: Contribution to journal › Article › peer-review

4 Scopus citations

Abstract

Isolated cobalt ions on nitrogen-doped carbon (Co-N-C) catalyze CO oxidation at temperatures as low as 196 K, but the active site and mechanism for this reaction remain elusive. In this work, steady-state CO oxidation around 273 K over Co-N-C revealed nearly first-order behavior in both CO and O2 as well as a negative apparent activation energy. Isotopic transient analysis of the reaction confirmed a rapid turnover frequency and low surface coverage of adsorbed intermediates leading to CO2 (<10% of the Co). Results from kinetics experiments combined with quantum chemical calculations and molecular dynamics simulations are consistent with a reaction path involving weak adsorption of CO onto Co ions followed by a low barrier for the CO-assisted activation of weakly adsorbed O2. This proposed mechanism for dioxygen activation does not involve a redox cycle with the transition-metal ion and may be important in other low-temperature catalytic reactions involving O2.

Original language	English
Pages (from-to)	15529-15540
Number of pages	12
Journal	ACS Catalysis
Volume	12
Issue number	24
DOIs	https://doi.org/10.1021/acscatal.2c04380
State	Published - Dec 16 2022

Funding

This research was sponsored by the U.S. National Science Foundation under grant #CBET-1802482. C.P. acknowledges the donors of the American Chemical Society Petroleum Research Fund for partial support of this research. This research used beamline 8-ID of the National Synchrotron Light Source II, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Brookhaven National Laboratory under Contract No. DE-SC0012704. Dr. Eli Stavitski provided technical assistance with operating beamline 8-ID. Scanning transmission electron microscopy research was conducted as part of a user project at the Center for Nanophase Materials Sciences (CNMS), which is a US Department of Energy, Office of Science User Facility at Oak Ridge National Laboratory. Helpful technical discussions with Sugandha Verma and Dr. Gordon Brezicki are also acknowledged.

Keywords

AIMD
CO oxidation
N-doped carbon
SSITKA
density functional theory
heterogeneous catalysis

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title = "Mechanistic Insights on the Low-Temperature Oxidation of CO Catalyzed by Isolated Co Ions in N-Doped Carbon",

abstract = "Isolated cobalt ions on nitrogen-doped carbon (Co-N-C) catalyze CO oxidation at temperatures as low as 196 K, but the active site and mechanism for this reaction remain elusive. In this work, steady-state CO oxidation around 273 K over Co-N-C revealed nearly first-order behavior in both CO and O2 as well as a negative apparent activation energy. Isotopic transient analysis of the reaction confirmed a rapid turnover frequency and low surface coverage of adsorbed intermediates leading to CO2 (<10% of the Co). Results from kinetics experiments combined with quantum chemical calculations and molecular dynamics simulations are consistent with a reaction path involving weak adsorption of CO onto Co ions followed by a low barrier for the CO-assisted activation of weakly adsorbed O2. This proposed mechanism for dioxygen activation does not involve a redox cycle with the transition-metal ion and may be important in other low-temperature catalytic reactions involving O2.",

keywords = "AIMD, CO oxidation, N-doped carbon, SSITKA, density functional theory, heterogeneous catalysis",

author = "Whitcomb, {Colby A.} and Anna Sviripa and Schapowal, {Michael I.} and Konstantin Mamedov and Unocic, {Raymond R.} and Christopher Paolucci and Davis, {Robert J.}",

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year = "2022",

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doi = "10.1021/acscatal.2c04380",

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T1 - Mechanistic Insights on the Low-Temperature Oxidation of CO Catalyzed by Isolated Co Ions in N-Doped Carbon

AU - Whitcomb, Colby A.

AU - Sviripa, Anna

AU - Schapowal, Michael I.

AU - Mamedov, Konstantin

AU - Unocic, Raymond R.

AU - Paolucci, Christopher

AU - Davis, Robert J.

PY - 2022/12/16

Y1 - 2022/12/16

N2 - Isolated cobalt ions on nitrogen-doped carbon (Co-N-C) catalyze CO oxidation at temperatures as low as 196 K, but the active site and mechanism for this reaction remain elusive. In this work, steady-state CO oxidation around 273 K over Co-N-C revealed nearly first-order behavior in both CO and O2 as well as a negative apparent activation energy. Isotopic transient analysis of the reaction confirmed a rapid turnover frequency and low surface coverage of adsorbed intermediates leading to CO2 (<10% of the Co). Results from kinetics experiments combined with quantum chemical calculations and molecular dynamics simulations are consistent with a reaction path involving weak adsorption of CO onto Co ions followed by a low barrier for the CO-assisted activation of weakly adsorbed O2. This proposed mechanism for dioxygen activation does not involve a redox cycle with the transition-metal ion and may be important in other low-temperature catalytic reactions involving O2.

AB - Isolated cobalt ions on nitrogen-doped carbon (Co-N-C) catalyze CO oxidation at temperatures as low as 196 K, but the active site and mechanism for this reaction remain elusive. In this work, steady-state CO oxidation around 273 K over Co-N-C revealed nearly first-order behavior in both CO and O2 as well as a negative apparent activation energy. Isotopic transient analysis of the reaction confirmed a rapid turnover frequency and low surface coverage of adsorbed intermediates leading to CO2 (<10% of the Co). Results from kinetics experiments combined with quantum chemical calculations and molecular dynamics simulations are consistent with a reaction path involving weak adsorption of CO onto Co ions followed by a low barrier for the CO-assisted activation of weakly adsorbed O2. This proposed mechanism for dioxygen activation does not involve a redox cycle with the transition-metal ion and may be important in other low-temperature catalytic reactions involving O2.

KW - AIMD

KW - CO oxidation

KW - N-doped carbon

KW - SSITKA

KW - density functional theory

KW - heterogeneous catalysis

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DO - 10.1021/acscatal.2c04380

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SN - 2155-5435

VL - 12

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JO - ACS Catalysis

JF - ACS Catalysis

IS - 24

ER -

Mechanistic Insights on the Low-Temperature Oxidation of CO Catalyzed by Isolated Co Ions in N-Doped Carbon

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