In-situ fabrication of Ce-rich CeO2 nanocatalyst for efficient CO oxidation

Abstract

Ceria is widely utilized in the field of CO catalysis due to its outstanding oxygen storage/release capacity (OSC/ORC). In this study, Ce precursor is successfully injected into the plasma electrolytic oxidation (PEO) film in silicate electrolyte through the addition of EDTA-2Na during PEO process. The atomic percentage (at. %) of Ce in PEO film can reach up to 14.80, which is the highest among all the related works. Annealing treatment in air ambient leads to the crystallization and oxidation reaction of Ce species, which mainly exist in the PEO film in amorphous phase and Ce4.667(SiO4)3O. During the annealing process, CeO2 nanocrystals (∼100 nm) are generated under the confinement of amorphous SiO2 layer in PEO film. Subsequent etching treatment removes the amorphous SiO2 capping layer and triggers the catalytic activity of CeO2 nanocrystals. CO oxidation test reveals that these CeO2 nanocatalysts own remarkable catalytic activity in CO oxidation and show strong synergistic effect with noble metal (Au). This study establishes an efficient in-situ fabrication route for the preparation of highly active metal-supported ceria nanocatalysts with strong substrate adherence, showing overwhelming advantage compared with traditional catalyst preparation methods, which is promising for the direct integration of various oxide catalysts towards CO oxidation, TWCs, SCR, etc.