Alloys Ostwald ripening

Agglomeration of Pt crystallites due to Brownian motion can really be observed and it can also be shown that, indeed, the interaction between the Pt particles and the supporting soot in the presence of the electrolyte, phosphoric acid, is weak enough to allow for relatively free movement of the Pt particles. This fast process obviously is also the reason for the nonobservability of slower surface diffusion-induced Ostwald ripening. Fortunately alloy catalysts composed of platinum and nonnoble metals seem to show a reduced tendency to agglomeration as their deterioration and activity loss is much slower than that of the pure platinum catalyst. 

Kuehmann, C.J. Voorhees, P.W. Ostwald ripening in ternary alloys. Metall. Mater. Trans. A. 1996, 27A, 937-943. 

The most plausible life-limiting factor is electrolyte depletion in the MCFC. Since the anode serves as electrolyte reservoir, its stable pore structure is very important for the electrolyte management. The Ni-Cr alloy electrodes, however, showed creep behavior, which deforms the pore structure due to 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. 

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