Search

This work presents an original approach to preparing pure and Ni-doped CeO2nanoparticles (NPs) that can be directly drop-casted on a substrate or calcined to form powders. The reduction of the NPs in H2is very different than the one usually anticipated for supported Ni–CeO2catalysts. In situ soft X-ray absorption and infrared spectroscopies revealed that the reduction of Ce4+into Ce3+in H2proceeds via simultaneous oxidation of Ni2+ions into Niδ+(2<δ<3). Comparison with reference samples indicates that Ce4+ions reduction is promoted over Ni-doped CeO2NPs, whereas that of Ni2+is hindered. Theoretical simulation of Ni L-edge spectra suggested that Ni dopant into ceria is in a square planar four-coordinate environment, in contrast to the familiar octahedral symmetry of bulk nickel oxides. Our results reveal that the surface chemistry of Ni-doped CeO2is quite distinct as compared to that of the individual bulk oxides, which potentially can lead to a different performance of this material, notably in catalytic applications.