Nanoparticle Ostwald ripening

Examples of atomistic models addressing PEMFC materials s stability and aging, a) DFT modeling of surface oxide formation b) atomistic description of nanoparticle (Ostwald) ripening c) calculation of surface and bulk composition of alloyed catalyst d) change of potential as function of alloy composition. 

The growth of the nanoparticles could have occurred either by the growth of CdSe on the seeds (growth from supersaturated solution) or by the process of Ostwald ripening whereby larger seed grow at the expense of the smaller ones. 

In terms of the common features of colloids just listed, nanoparticles with a clean surface have tendency to amalgamate when placed on a TEM sample mesh that is evident in Figures 9.4.16 and 9.4.17. Furthermore, the particles often grow by collision (not by Ostwald ripening because metal ions are hard to dissolve in organic liquids) in the suspension state when the number density of particles in... 

Fig. 18.5 TEM images and Gaussian fits of the size distribution of the palladium nanoparticles initially (a, b), after being exposed to the solvent (1 3 water acetonitrile) and the base (sodium acetate SA) (c, d), after being exposed to the base and phenylboronre acid (PA) (e, f), and after being exposed to the base and iodobenzene (I) (g, h). It can be seen that the Ostwald ripening process is inhibited upon exposure to the phenylboronic acid while exposure to iodobenzene results in the growth of the nanoparticles. In addition, refluxing the nanoparticles in the solvent alone also results in the Ostwald ripening of the particles. Reprinted with permission from [40]. Copyright 2003, American Chemical Society...

E2432 Ostwald ripening is a process in which smaller particles present in the solution dissolve and this redisolved material precipitates again but on the surface of existing particles. The Ostwald ripening decreases the number of particles in the solution and increases size distribution and thus is an unwanted process during nanoparticle... 

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