CO oxidation on a single Pd atom supported on magnesia

The oxidation of CO on Single Pd atoms anchored to MgO(100) surface oxygen vacancies is studied with: temperature-programmed-reaction mass spectrometry and infrared spectroscopy. In one-heating-cycle experiments, CO2, formed from O-2 and CO preadsorbed at 90 K, is detected at 260 and 500 K. Ab-initio simulations suggest two reaction routes, with Pd(CO)(2)O-2 and PdCO3CO found as precursors for the low and high temperature channels, respectively. Both reactions result in annealing of the vacancy and induce migration and coalescence of the remaining Pd-CO to form larger clusters.