Fundamental studies of three C1 molecules (CO, CO2, and CH3OH/CD3OD) adsorption on surfaces of ceria single crystals and/or nanocrystals have been carried out by using ultra-high vacuum Fourier transform infrared spectroscopy (UHV-FTIRS) or near-edge X-ray absorption fine structure (NEXAFS) spectroscopy. The oxidation states of cerium cations were determined by the core-level and valence band X-ray photoelectron spectroscopy (XPS)
