  We theoretically study the electrolyte Seebeck effect in the vicinity of a
heated metal nanostructure, such as the cap of an active Janus colloid in an
electrolyte, or gold- coated interfaces in optofluidic devices. The
thermocharge accumulated at the surface varies with the local temperature, thus
modulating the diffuse part of the electric double layer. On a conducting
surface with non-uniform temperature, the isopotential condition imposes a
significant polarization charge within the metal. Surprisingly, this does not
affect the slip velocity, which takes the same value on insulating and
conducting surfaces. Our results for specific-ion effects agree qualitatively
with recent observations 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, extending
to microseconds after switching on the heating.
