  A simple theoretical approach is used to investigate active colloids at the
free interface and near repulsive substrates. We employ dynamical density
functional theory to determine the steady-state density profiles in an
effective equilibrium system [Farage et al., Phys. Rev. E, 91 (2015) 042310].
In addition to the known accumulation at surfaces, we predict wetting and
drying transitions at a flat repulsive wall and capillary condensation and
evaporation in a slit pore. These new phenomena are closely related to the
motility-induced phase separation (MIPS) in the bulk.
