Abstract:The catalytic behaviour of Ag 2 O and Ag doped CeO 2 thin films, deposited by atomic layer deposition (ALD), was investigated for diesel soot oxidation. The silver oxide was deposited from pulses of the organometallic precursor (hfac)Ag(PMe 3 ) and ozone at 200 • C with growth rate of 0.28 Å/cycle. Thickness, crystallinity, elemental composition, and morphology of the Ag 2 O and Ag doped CeO 2 films deposited on Si (100) were characterized by ellipsometry, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and field emission scanning electron microscopy (FESEM), respectively. The catalytic effect on diesel soot combustion of pure Ag 2 O, CeO 2, and Ag doped CeO 2 films grown on stainless steel foil supports was measured with oxidation tests. Nominally CeO 2 :Ag 10:1 doped CeO 2 films were most effective and oxidized 100% of soot at 390 • C, while the Ag 2 O films were 100% effective at 410 • C. The doped films also showed much higher stability; their performance remained stable after five tests with only a 10% initial reduction in efficiency whereas the performance of the Ag 2 O films reduced by 50% after the first test. It was concluded that the presence of Ag + sites on the catalyst is responsible for the high soot oxidation activity.