The electronic properties of Ni and Pt nanoparticles deposited on CeO2 have been examined using core and valence photoemission. The results of valence photoemission point to a new type of metal-support interaction which produces large electronic perturbations for small Ni and Pt particles in contact with ceria. The Ni/CeO2 and Pt/CeO2 systems exhibited a density of metal d states near the Fermi level that was much smaller than that expected for bulk metallic Ni or Pt. The large electronic perturbations seen for small Pt particles in contact with ceria significantly enhanced the ability of the admetal to adsorb and dissociate water and made it a highly active catalyst for the water-gas shift. On the other hand, the electronic perturbations induced by ceria on Ni made this metal a very poor catalyst for CO methanation, but transformed Ni into an excellent catalyst for the production of hydrogen through the water-gas shift and the reforming of alcohols or methane. Ni/CeO2 is able to activate methane at room temperature and at relatively low temperatures (450-550 K) performs the conversion of methane into methanol. The behaviour seen for the Ni/CeO2 and Pt/CeO2 systems illustrates the positive effects derived from electronic metal-support interactions and points to a promising approach for improving or optimizing the performance of metal/oxide catalysts.

Metal-support interactions and C1 chemistry on Ni-CeO2 surfaces

2019 Fall National Meeting

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