In-situ study of the catalytic oxidation of CO on a Pt(1Â 1Â 0) surface using ambient pressure X-ray photoelectron spectroscopy

CO and O2 co-adsorption and the catalytic oxidation of CO on a Pt(1 1 0) surface under various pressures of CO and O2 (up to 250 mTorr) are studied using ambient pressure X-ray photoelectron spectroscopy (APXPS) and mass spectrometry. There is no surface oxide formation on Pt under our reaction conditions. CO oxidation in this pressure (<500 mTorr), O2 to CO ratio (<10), and temperature (150 °C) regime is consistent with the Langmuir-Hinshelwood reaction mechanism. Our findings provide in-situ surface chemical composition data of the catalytic oxidation of CO on Pt(1 1 0) at total pressures below 1 Torr.