Diffusiophoretic Drive for Catalytic Janus Particles

In this talk, we discuss our recent theoretical/numerical investigation into the properties of the self-diffusiophoretic mechanism, by which active colloidal Janus particles can achieve self-propulsion. Our multi-component approach is introduced and we derive a system of coupled momentum transport, diffusion, advection, and reaction equations that need to be solved simultaneously to determine the particle's motion. We discuss the limitations of our model and the way it differs from previous descriptions of the active multi-component system. Using this formalism, we explore the influence of the solvent- and solute-surface interaction for a Janus particle that is partially catalytic. We show that small variations in the solute-surface interaction can lead to substantial changes in the velocity of the colloid, and highlight other features of this model as well. From our observations we conclude the following. On the one hand, the model is extremely sensitive to the solute-surface interactions, making it difficult to make a reliable comparison to experimental measurements. On the other hand, taking into account differences between the solute-catalytic and solute-inert surface interaction, may lead to unexpected behavior of the particles, which might be exploited in real-world applications. Finally, we comment on extensions of our results to more complicated geometries and our ongoing work to utilize this model in lattice-Boltzmann simulations.