  The adsorption effects of small molecules (H$_{2}$O, CO, NH$_{3}$, NO$_{2}$)
and large molecules (Tetracyanoquinodimethane (TCNQ) and
Tetrafluoro-tetracyanoquinodimethane (F4TCNQ)) on electronic and magnetic
properties of two triangular graphene antidot lattices (GALs), $[10,3,6]_{RTA}$
and $[10, 5]_{ETA}$, are investigated by means of first-principles
calculations. We find that CO, NO$_{2}$, TCNQ, and F4TCNQ molecules are
chemisorbed by both antidots, whereas NH$_{3}$ is physisorbed (chemisorbed) by
$[10, 5]_{ETA}$ ($[10,3,6]_{RTA}$) structure. H$_{2}$O, CO, NH$_{3}$ molecules
reveal no significant effect on electronic and magnetic properties of these
antidot structures. The adsorbed NO$_{2}$ molecules affect the energy gap of
GALs by changing their electronic structure from semiconducting to half-metal
nature. This suggests that both GALs can act as efficient NO$_{2}$ sensors. The
adsorption of TCNQ and F4TCNQ molecules on GALs induces flat bands in the
vicinity of the Fermi energy and also turn the electronic structure of antidot
lattices to half-metallicity. Among the small and large molecules, NO$_{2}$
molecules induce the most total magnetic moment, paving the way to make
magnetic GAL-based devices.
