  Chemically active Janus particles generate tangential concentration gradients
along their surface for self-propulsion. Although this is well studied in
unbounded domains, the analysis in biologically relevant environments such as
confinements is scarce. In this work, we study the motion of a Janus sphere in
weak confinement. The particle is placed at an arbitrary location, with an
arbitrary orientation between the two walls. Using the method of reflections,
we study the effect of confining planar boundaries on the phoretic and
hydrodynamic interactions, and their consequence on the Janus particle
dynamics. The dynamical trajectories are analyzed using phase diagrams for
different surface coverage of activity and solute-particle interactions. In
addition to near wall states such as `sliding' and `hovering', we demonstrate
that accounting for two planar boundaries reveals two new states:
channel-spanning oscillations and damped oscillations around the centerline,
which were characterized as `scattering' or `reflection' by earlier analyses on
single-wall interactions. Using phase diagrams, we highlight the differences in
inert-facing and active-facing Janus particles. We also compare the dynamics of
Janus particles with squirmers for contrasting the chemical interactions with
hydrodynamic effects. Insights from the current work suggest that biological
and artificial swimmers sense their surroundings through long-ranged
interactions, that can be modified by altering the surface properties.
