Fig. 3: Morphology characterization and physicochemical properties of the membranes.

a–e Surface SEM, Cross-sectional TEM, and AFM images of Tp-Bth (a, c) and TFB-Bth (b, d) COF membranes (insert: digital images of COF membranes with a diameter of 4.5 cm). f, g XPS spectra and Zeta potentials of Kevlar, Tp-Bth, and TFB-Bth COF membranes. h, i N2 adsorption-desorption isotherm and pore size distributions for the Tp-Bth and TFB-Bth nanofilms. j The rejection performance of uncharged organic solutes (the feed concentration is 1000 ppm).