Previous publications demonstrate the stability of 2D COFs comprised of triazine, benzene, and boroxine rings. Prakhira S., et al. theoretically predicted the stability of this 2D COF architecture in its bulk configuration, and Gontarczyk K., et al. experimentally synthesized this structure (labeled BTA-COF4 in their publication). In these publications, the 2D COF was calculated/synthesized as a bulk structure comprised of many stacked layers. However, in our work, we focus on a freestanding 2D COF bilayer, which has not been theoretically predicted or experimentally synthesized in the past. This material is expected to present different electronic properties compared to its bulk counterpart, due to electron confinement in two dimensions. Figure shows the structural features and electronic properties of the pristine bilayer triazine-benzene-boroxine 2D COF. Geometry optimization using unrestricted hybrid Density Functional Theory with Grimme of the Supplementary Information. Figure shows a top view of the optimized structure, where the eclipsed 2D COF stacking can be observed. This figure also shows the spin-polarized band structure and atom-projected density of states (DOS) (middle and right-hand side of the figure), showing that the distribution of spin-up and spin-down electrons is symmetrical in this material, which is expected from its non-magnetic configuration. The material presents a bandgap of 3.40 eV, indicating insulating electronic behavior. Comparatively, its bulk counterpart was predicted to have a smaller bandgap of about 2.6 eV. Furthermore, the DOS reveals that carbon atoms are the main contributors to the electronic states around the Fermi level, i.e., near the conduction band minimum (CBM) and valence band maximum (VBM). The dynamical stability of the pristine bilayer 2D COF was confirmed through vibrational calculations at the Γ, M, and K reciprocal lattice points, which revealed no imaginary frequency modes, indicating a stable structure. The pristine optimized structure was taken as a starting point to generate the intercalated 2D COFs. Transition metals were positioned at the centroid of the bilayer COF rings in different concentrations. Intercalants and concentrations will be referred to as TM-01 through TM-05, where TM = [Co, Cr, Cu, Fe, Mn, Ni, Sc, Ti, and V]. There are two variations of TM-01 and TM-04, which we distinguish by adding "a" or "b" to the name. Therefore, we generated seven different atomic configurations each with nine TM intercalants, resulting in a total of 63 intercalated bilayer 2D COFs. Configuration TM-01a has one transition metal per unit cell, positioned at the centroid of boroxine rings. TM-01b also has one transition metal per unit cell, positioned at the centroid of triazine rings. TM-02 has two transition metals per unit cell, placed at the centroid of boroxine and triazine rings. TM-03 has three transition metals per unit cell, located at the centroid of all benzene rings. TM-04a has four transition metals per unit cell, intercalated at the centroid of all benzene and boroxine rings. TM-04b also has four transition metals per unit cell, intercalated at the centroid of all benzene and triazine rings. Finally, TM-05 has transition metals located at the centroid of all rings in the structure (triazine, benzene, and boroxine).