Acid Spacers Endowing g‐C₃N₄ membranes with Superior Permeability and Stability

: g-C3 N4 membranes were modulated by intercalating molecules with SO3 H and benzene moieties between layers. The intercalation molecules break up the tightly stacking structure of g-C3 N4 laminates successfully and accordingly the modified g-C3 N4 membranes give rise to two orders magnitude higher water permeances without sacrificing the separation efficiency. The sulfonated poly(2,6-dimethyl-1,4-phenylene oxide) (SPPO)/g-C3 N4 with a thickness of 350 nm presents an exceptionally high water permeance of 8867 L h-1  m-2  bar-1 and 100 % rejection towards methyl blue, while the original g-C3 N4 membrane with a thickness of 226 nm only exhibits a permeance of 60 L h-1  m-2  bar-1 . Simultaneously, SO3 H sites firmly anchor nitrogen with base functionality distributing onto g-C3 N4 through acid-base interactions. This enables the nanochannels of g-C3 N4 based membranes to be stabilized in acid, basic, and also high-pressure environments for long periods.