Nanoscale Seebeck effect of thermally powered active Janus colloids

We theoretically study the Seebeck effect in the vicinity of a heated metal nanostructure, such as the gold cap of an active Janus colloid in an electrolyte. The thermocharge varies with the surface temperature, thus modulating the diffuse layer of an insulating surface, and inducing polarization charges on an electric conductor. The isopotential boundary condition on a metal surface, results in a reduction of the slip velcoity. Our results agree with recently observed specific-ion effects for Janus colloids in different electrolyte solutions. Comparing the thermal, hydrodynamic, and ion diffusion time scales, we expect a rich transient behavior at the onset of thermally powered swimming, ranging well beyond microseconds.