High-porosity Pt-CeO nanosponges as oxidation catalyst.

Pt-CeO nanosponges (1 wt% Pt) with high surface area (113 m g), high pore volume (0.08 cm g) and small-sized Pt nanoparticles (1.8 ± 0.4 nm) are prepared by thermal decomposition of a cerium oxalate precursor and examined for catalytic oxidation of CO, volatile organic compounds (VOCs), and NH. The cerium oxalate precursor Ce(CO)·10HO is prepared by aqueous precipitation from Ce(NO)·6HO and KCO·HO and thermally converted to CeO nanosponges by heating in air. Optimal conditions for decomposition in terms of surface area and porosity are observed at 350 °C for 20 min. Finally, the CeO nanosponges are decorated with small-sized Pt nanoparticles, using a wet-chemical impregnation with Pt(ac) in methanol. Electron microscopy with tomography, electron spectroscopy and further methods (TG, XRD, FT-IR, sorption analysis) are used to characterize the catalyst composition and especially the structure and porosity of the Pt-CeO nanosponges as well as the uniform distribution of the Pt nanoparticles. The Pt-CeO nanosponges show good thermal stability (up to 400 °C) and, already as a new, non-optimized catalyst, promising activity for catalytic oxidation of CO, VOCs, NH as indicated by high activities in terms of low and stable light-out and light-off temperatures as well as a high selectivity to N (for NH oxidation) with >80% at 170-250 °C.