Molecular origins of surface poisoning during CO oxidation over RuO2(1Â 1Â 0)

Metal oxides are of interest as environmental oxidation catalysts, but practical applications are often limited by poorly understood surface poisoning processes. RuO2 is active for CO oxidation under UHV conditions but is deactivated by some surface poisoning processes at ambient pressures. In this work, we report kinetic models of surface poisoning during CO oxidation over RuO2(1 1 0), based on data obtained from plane-wave, supercell DFT calculations. While a surface carbonate CO32- is stable at low O2 pressures and high CO2 exposures, it is not stable under catalytic conditions. A surface bicarbonate HCO3- is more stable and deactivates the RuO2 surface over a wide range of CO and oxygen pressures in the presence of trace amounts of water.