title: High-spatial-resolution mapping of catalytic reactions on single particles.
abstract: The critical role in surface reactions and heterogeneous catalysis of metal atoms with low coordination numbers, such as found at atomic steps and surface defects, is firmly established. But despite the growing availability of tools that enable detailed in situ characterization, so far it has not been possible to document this role directly. Surface properties can be mapped with high spatial resolution, and catalytic conversion can be tracked with a clear chemical signature; however, the combination of the two, which would enable high-spatial-resolution detection of reactions on catalytic surfaces, has rarely been achieved. Single-molecule fluorescence spectroscopy has been used to image and characterize single turnover sites at catalytic surfaces, but is restricted to reactions that generate highly fluorescing product molecules. Herein the chemical conversion of N-heterocyclic carbene molecules attached to catalytic particles is mapped using synchrotron-radiation-based infrared nanospectroscopy with a spatial resolution of 25 nanometres, which enabled particle regions that differ in reactivity to be distinguished. These observations demonstrate that, compared to the flat regions on top of the particles, the peripheries of the particles-which contain metal atoms with low coordination numbers-are more active in catalysing oxidation and reduction of chemically active groups in surface-anchored N-heterocyclic carbene molecules.
authors.affiliation: Department of Chemistry, University of California, Berkeley, California 94720, USA.|Chemical Sciences Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720, USA.
authors.forename: Chung-Yeh
authors.initials: CY
authors.lastname: Wu
authors.affiliation: Department of Chemistry, University of California, Berkeley, California 94720, USA.|Chemical Sciences Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720, USA.
authors.forename: William J
authors.initials: WJ
authors.lastname: Wolf
authors.affiliation: Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904, Israel.|The Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Jerusalem 91904, Israel.
authors.forename: Yehonatan
authors.initials: Y
authors.lastname: Levartovsky
authors.affiliation: Advanced Light Source, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720, USA.
authors.forename: Hans A
authors.initials: HA
authors.lastname: Bechtel
authors.affiliation: Advanced Light Source, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720, USA.
authors.forename: Michael C
authors.initials: MC
authors.lastname: Martin
authors.affiliation: Department of Chemistry, University of California, Berkeley, California 94720, USA.|Chemical Sciences Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720, USA.
authors.forename: F Dean
authors.initials: FD
authors.lastname: Toste
authors.affiliation: Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904, Israel.|The Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Jerusalem 91904, Israel.
authors.forename: Elad
authors.initials: E
authors.lastname: Gross