Post-Synthesis Ion Beam Sputtering of Pt/CeO2–ZrO2 Catalysts: Correlating Surface Modifications with Light-Off Performance

High-efficiency diesel and lean-burn engines produce lower exhaust temperatures, which
can delay the activation of after-treatment catalysts such as Diesel Oxidation Catalysts
(DOCs). This study explores ion beam sputtering as a post-synthesis strategy to enhance
the low-temperature activity of commercial Pt/CeO2–ZrO2 catalysts. Low-energy ions
(0.5–1.5 keV) were applied with controlled variations in treatment number, beam current,
and exposure time to selectively generate oxygen vacancies and improve Pt dispersion.
Structural and chemical effects were characterized using X-ray diffraction (XRD), BET
surface area measurements, X-ray photoelectron spectroscopy (XPS) and extended X-ray
absorption fine structure (EXAFS). Catalytic performance was evaluated through CO and
C3H6 oxidation under conditions mimicking lean-burn engine exhaust. Increasing the
number of ion treatments progressively lowered light-off temperatures, correlating with
enhanced Pt–Ce3+ interactions and improved surface reducibility. Variations in beam
current and exposure time further modulated these surface effects, confirming the tunable
nature of the approach. The results demonstrate that ion beam sputtering selectively
modifies the catalyst surface without altering the bulk structure, directly linking atomicscale
modifications to improved low-temperature activity. This strategy offers a promising
route to overcome delayed light-off issues in modern high-efficiency engines, providing a
precise, controllable method to optimize emission control catalysts.