Direct observation of hydrogen spillover in Ni-loaded Pr-doped ceria

In situ studies on reduction processes in praseodymium-doped ceria and nickel-loaded doped ceria nanoparticles have been investigated using environmental transmission electron microscopy. The presence of pit-like defects on the oxide nanoparticles resulted in amorphization during reduction. Hydrogen-spillover in nickel-loaded praseodymium-doped ceria (PDC) was directly observed. Localized reduction of ceria in a H2 atmosphere was observed and attributed to gas–nickel–ceria interactions at the three-phase boundary. The spatial extent of the localized reduction zones was experimentally determined. The spillover mechanism is discussed in terms of surface diffusion properties of atomic hydrogen and oxygen species.