A Chemical Mechanism for the Bistable‐to‐Oscillatory Transition in Colloidal Aggregates of Silver Phosphate

Abstract

We previously reported collective behavior in colloidal aggregates of silver phosphate in H2O2 and under UV light. Diffusiophoretic interactions between aggregates lead to non‐linear behavior such as oscillations and synchronization, in which oscillation frequencies increase with H2O2 concentration. The aggregates transition between schooling and dispersed behaviors with incipient spatiotemporal correlations. We identified a kinetic model that maps the chemical species that are thought to underlie non‐linear phenomena in the colloidal aggregates, i.e. adsorbed oxygen species *OOH and ∗O. We investigate the emergent dynamics for the simplest case, the coupling of two otherwise bistable clusters. Two coupling schemes are proposed and we find that – depending on whether the coupling is excitatory or inhibitory – the clusters may oscillate with zero or π phase shift.