Cu-Enhanced Surface Defects and Lattice Mobility of Pr-CeO2 Mixed Oxides

Abstract

The surface properties of CeO2, Pr-CeO2, and 5% and 15% Cu-doped Pr-CeO2 were investigated using methanol as a probe molecule through adsorption and desorption studies carried out using in situ DRIFTS. It was revealed that the surfaces of the 5% and 15% Cu materials were dominated by reduced cations/vacancies and that the 15% Cu material contained the highest concentration of these active species. The high oxygen storage capacity (OSC) of the 15% Cu material, as determined using TGA, reflects the available vacant sites for oxygen adsorption. Formates were formed on all materials, with those formed on the Cu-doped materials present at temperatures as low as 25 °C, hence showing their superior reactivity toward methoxy oxidation. During formate dehydrogenation, H2, CO, CO2, and H2O evolved as the surface cations were simultaneously reduced. It was also observed that, for the Cu-containing materials, H2 was not formed and the high surface mobility determined through isotopic exchange simultaneously generated...