Structure and Catalytic Properties of Nano-Sized Alumina Supported Platinum and Palladium Particles Synthesized by Reaction in Microemulsion
Journal article, 2003

Mixtures of nanosized platinum and palladium particles have been prepared by reduction of salt-containing microemulsion droplets using hydrazine as the reducing agent. To avoid possible negative effects of the presence of sulfur compounds during the preparation the microemulsion was made using the sulfur-free nonionic polyoxyethylene 4 lauryl ether surfactant. Transmission electron microscopy showed that the as-prepared mixtures contained crystalline platinum particles of fairly homogeneous size (20 to 40 nm) with adsorbed amorphous palladium particles 2 to 5 nm in size. Catalyst samples were prepared by depositing the nanoparticles on a γ-Al2O3 support followed by heating in air at 600 °C. Alloyed particles of platinum and palladium with sizes ranging from 5 to 80 nm were obtained during the heating. The majority of the particles had the fcc structure and their compositional range was dependent upon the Pt:Pd molar ratio of the microemulsion. A catalyst prepared from a microemulsion with a 20:80 Pt:Pd molar ratio showed the highest catalytic activity for CO oxidation, while pure platinum and palladium catalysts showed higher sulfur resistance. These results differ from the performance of conventional wet-impregnated catalysts, where a 50:50 Pt:Pd molar ratio resulted in the highest catalytic activity as well as the highest sulfur resistance.


Electron microscopy

Catalyst preparation


Alloyed nanoparticles

CO oxidation


Nanoparticle synthesis



Masatomo Yashima

Lena Falk

Chalmers, Department of Experimental Physics, Microscopy and Microanalysis

Anders Palmqvist

Chalmers, Department of Materials and Surface Chemistry, Applied Surface Chemistry

Competence Centre for Catalysis (KCK)

Krister Holmberg

Competence Centre for Catalysis (KCK)

Chalmers, Department of Materials and Surface Chemistry, Applied Surface Chemistry

Journal of Colloid and Interface Science

0021-9797 (ISSN) 1095-7103 (eISSN)

Vol. 268 2 348-356

Subject Categories

Inorganic Chemistry

Physical Chemistry

Driving Forces

Sustainable development

Areas of Advance

Nanoscience and Nanotechnology

Materials Science


Basic sciences

More information