Structural Stabilization of Metal Nanoparticles by Chemical Vapor Deposition-Applied Silica Coatings

The structure of aerosol Pd nanoparticle ensembles was stabilized against a loss of surface area during tempering by application of a thin silica coating by chemical vapor deposition in the gas-borne state. The coating was applied to the surfaces of particles prior to ensemble formation and after, yielding two different types of structures. The pure Pd and the stabilized structures were tempered at varied residence times and temperatures to analyze the sintering kinetics as a function of the type of structure. The sintering kinetics of clean Pd particles could be approximated using the general power law expression model. Stabilization of the nanoparticles was accomplished for both coating approaches. A stabilization of the super ordinate structure, however, was only possible by a coating of the ensemble as a whole.