Low-Temperature Dissociation of CO2 on a Ni/CeO2(111)/Ru(0001) Model Catalyst

The adsorption of CO, on CeO2-x(111) and Ni/CeO2-x(111)/Ru(0001) surfaces has been studied with reflection absorption infrared spectroscopy (RAIRS) and Xray photoelectron spectroscopy (XPS). On the maximal-oxidized CeO2(111) surface physisorbed linear CO2 and a CO2- species are identified at 97 K. The reduced CeO2-x(111) surface exhibits higher reactivity toward adsorbed CO2, which leads to higher coverages of CO2- and promotes CO2 dissociating into CO and an active oxygen species at higher temperature, reoxidizing the reduced CeO2-x(111) films. Deposition of Ni on the maximal-oxidized CeO2 thin films leads to slight reduction of ceria films. Adsorption of CO, on Ni/CeO2-x(111) films causes dissociation at 97 K and leads to Ni-CO adsorbates plus partial oxidation of Ni nanoparticles. This process is inhibited when Ni nanoparticles on CeO2 are fully oxidized. In contrast to the results reported for CO, adsorption on Ni single-crystals, where the dissociation temperature was found to be higher than 240 K, the much lower dissociation temperature (similar to 97 K) for CO2 on Ni nanoparticles supported on CeO2(111) suggests that the Ni/CeO2 catalyst exhibits high activity toward CO2 activation.