Promotional Effects and Reconstruction of Pt/CeOx and Pt/SiO2 Model Catalysts Produced by Electron-Beam Lithography (EBL)

We have studied the activity and stability of EBL-fabricated Pt/CeOx and Pt/SiO2 supported model catalysts during catalytic reactions. Different mixtures of H2+O2 diluted in argon and CO+O2 diluted in argon have been used in the temperature range 300–475°C. Reaction-induced morphology changes are observed for both types of samples after heat treatments in mixtures of H2+O2 diluted in argon. The EBL-fabricated samples are stable for reproducible CO oxidation measurements for at least a period of 50 h at 400°C. Pre-reduction at 400°C is shown to be favorable for CO oxidation in rich mixtures for the EBL-fabricated Pt/CeOx catalyst, while the opposite is measured for the EBL-fabricated Pt/SiO2 catalyst. Two powder samples, Pt/CeOx and Pt/SiO2, have also been tested during similar pre-treatment studies. Increased activity for CO oxidation (rich conditions) is found for both types of samples after pre-reduction, compared with pre-oxidation.