A Reactive Oxide Overlayer on Rhodium Nanoparticles during CO Oxidation and Its Size Dependence Studied by In Situ Ambient‐Pressure X‐ray Photoelectron Spectroscopy

The smaller, the better: In situ synchrotron ambient pressure X-ray photoelectron spectroscopy allows examination of the oxidation state of the surface of the rhodium nanoparticles (NPs) during CO oxidation in an O2 atmosphere. 2 nm NPs oxidize to a larger extent than 7 nm NPs during reaction at 150–200 °C, which correlates with a fivefold increase in turnover frequency for the smaller nanoparticles. Detailed facts of importance to specialist readers are published as "Supporting Information". Such documents are peer-reviewed, but not copy-edited or typeset. They are made available as submitted by the authors. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.