jz5009483_si_001.pdf (2.83 MB)
Trapping of Mobile Pt Species by PdO Nanoparticles under Oxidizing Conditions
journal contribution
posted on 2015-12-17, 02:43 authored by Cristihan Carrillo, Tyne R. Johns, Haifeng Xiong, Andrew DeLaRiva, Sivakumar
R. Challa, Ronald S. Goeke, Kateryna Artyushkova, Wei Li, Chang H. Kim, Abhaya K. DatyePt is an active catalyst for diesel
exhaust catalysis but is known
to sinter and form large particles under oxidizing conditions. Pd
is added to improve the performance of the Pt catalysts. To investigate
the role of Pd, we introduced metallic Pt nanoparticles via physical
vapor deposition to a sample containing PdO nanoparticles. When the
catalyst was aged in air, the Pt particles disappeared, and the Pt
was captured by the PdO, forming bimetallic Pt–Pd nanoparticles.
The formation of metallic Pt–Pd alloys under oxidizing conditions
is indeed remarkable but is consistent with bulk thermodynamics. The
results show that mobile Pt species are effectively trapped by PdO,
representing a novel mechanism by which Ostwald ripening is slowed
down. The results have implications for the development of sinter-resistant
catalysts and help explain the improved performance and durability
of Pt–Pd in automotive exhaust catalytic converters.