Fig. 2

Characterizations of crystal and porous structures for g-CxNy-COFs. a Illustration of synthetic procedures of g-CxNy-COFs. b, c and d PXRD patterns for g-C40N3-COF, g-C31N3-COF, and g-C37N3-COF: comparison between the experimental (red circle) and Pawley refined (black) profiles, the simulated patterns for eclipsed AA stacking mode (blue), the Bragg positions (green) and the refinement differences (orange). Insets: the crystal structures of corresponding g-CxNy-COFs assuming the eclipsed stacking viewed along [001] directions. e, f and g Nitrogen adsorption and desorption isotherms of g-C40N3-COF, g-C31N3-COF, and g-C37N3-COF. Insets: the pore size distributions calculated from non-local density functional theory