Trapping of Mobile Pt Species by PdO Nanoparticles under Oxidizing Conditions.
Pt 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.
†Department of Chemical and Biological Engineering and Center for Microengineered Materials, University of New Mexico, Albuquerque, New Mexico 87131, United States.
Cristihan
C
Carrillo
†Department of Chemical and Biological Engineering and Center for Microengineered Materials, University of New Mexico, Albuquerque, New Mexico 87131, United States.
Tyne R
TR
Johns
†Department of Chemical and Biological Engineering and Center for Microengineered Materials, University of New Mexico, Albuquerque, New Mexico 87131, United States.
Haifeng
H
Xiong
†Department of Chemical and Biological Engineering and Center for Microengineered Materials, University of New Mexico, Albuquerque, New Mexico 87131, United States.
Andrew
A
DeLaRiva
†Department of Chemical and Biological Engineering and Center for Microengineered Materials, University of New Mexico, Albuquerque, New Mexico 87131, United States.
Sivakumar R
SR
Challa
‡Sandia National Laboratories, Albuquerque, New Mexico 87185, United States.
Ronald S
RS
Goeke
†Department of Chemical and Biological Engineering and Center for Microengineered Materials, University of New Mexico, Albuquerque, New Mexico 87131, United States.
Kateryna
K
Artyushkova
§Chemical Sciences and Materials Systems Lab, General Motors Global Research and Development, Warren, Michigan 48090, United States.
Wei
W
Li
§Chemical Sciences and Materials Systems Lab, General Motors Global Research and Development, Warren, Michigan 48090, United States.
Chang H
CH
Kim
†Department of Chemical and Biological Engineering and Center for Microengineered Materials, University of New Mexico, Albuquerque, New Mexico 87131, United States.
Abhaya K
AK
Datye
Ostwald ripening; TEM; bimetallic nanoparticles; diesel oxidation catalyst; sintering