Functionalized Clay Microparticles as Catalysts for Chemical Oscillators

Catalytic micro- and nanoparticles are widely employed to study the global behavior of large networks of coupled chemical oscillators. In this paper, we present a new class of catalysts for the BZ oscillating reaction, based on the functionalization of natural inorganic materials (1:1 and 2:1 clays) through the sorption of the iron-complex ferroin on their surface. The small size of the clay basic units (diameter < 2 μm) and their colloidal nature make these particles interesting for studying systems having dimensions at the border between the nano- and the mesoscale. In the first part of this paper, we present the synthesis and the characterization of the ferroin-functionalized clay. We then show an extensive study on the oscillatory dynamics of the BZ reaction catalyzed by the clay. Through a direct comparison with a classical ferroin-catalyzed BZ system, we describe the modifications of the oscillation mechanisms induced by the new catalyst. Finally, we illustrate an application of the microparticles as a solid support for the study of synchronization in a network of independent chemical oscillators, showing that the diffusion of intermediate species can be fine-tuned through the stirring rate of the solution where the catalytic spots are soaked. The global system can be thus switched from a noncoupled to a coupled state.