Apr 21, 2009
Viscosity adjustments benefit catalyst production
The impregnation method is most widely used for the preparation of supported metal catalysts because the process is simple, but controlling the size and size distribution of metal particles can be difficult. Analysis indicates that solvent viscosity influences particle size, and consequently may help to tune the morphology of nanoparticles formed in solution.
To explore the idea, researchers at the Changchun Institute of Applied Chemistry, China, used various alcohol solvents with different chain lengths, and consequently different viscosities, to synthesize a carbon supported palladium catalyst. The results showed that the size of palladium particles could be facilely controlled by simply tuning the impregnation method's solvent media. They also helped the team to better understand the role of viscosity in the aggregation of metal particles.
When n-butanol was used as the solvent, the researchers were able to obtain a Pd/C catalyst with an average size in the region of 3 nm and a narrow size distribution. The material was applied to a direct formic acid fuel cell, where it presented a large electrochemically active surface area and high catalytic activity for formic acid electro-oxidation. The preparation method is simple and could benefit the synthesis of mass-produced Pd/C catalysts and the other noble metal catalysts for fuel cell applications.
The group presented its work in Nanotechnology.
About the author
This work was performed at Changchun Institute of Applied Chemistry (CIAC), Chinese Academy of Sciences, and supported by the High Technology Research Program of Science and Technology Ministry of China, and the National Natural Science Foundation of China. Prof. Wei Xing is the head of the fuel cell group at CIAC. His research covers proton exchange membrane fuel cells and direct alcohol fuel cells, as well as bio-electrochemistry. Yunjie Huang is a PhD student studying physical chemistry in the fuel cell group at CIAC and is currently investigating catalysts for use in direct alcohol fuel cells.