  A heterogeneous and dilute suspension of catalytically active colloids is
studied as a non-equilibrium analogue of ionic systems, which has the
remarkable feature of action-reaction symmetry breaking. Symmetrically coated
colloids are found to join up to form self-assembled molecules that could be
inert or have spontaneous activity in the form of net translational velocity
and spin depending on their symmetry properties and their constituents. The
type of activity can be adjusted by changing the surface chemistry and ambient
variables that control the surface reactions and the phoretic drift.

Soft Condensed Matter