Two-dimensional (2D) graphitic carbon nitride (g-C3 N4 ) nanosheets show brilliant application potential in numerous fields. Herein, a membrane with artificial nanopores and self-supporting spacers was fabricated by assembly of 2D g-C3 N4 nanosheets in a stack with elaborate structures. In water purification the g-C3 N4 membrane shows a better separation performance than commercial membranes. The g-C3 N4 membrane has a water permeance of 29 L m-2 h-1 bar-1 and a rejection rate of 87 % for 3 nm molecules with a membrane thickness of 160 nm. The artificial nanopores in the g-C3 N4 nanosheets and the spacers between the partially exfoliated g-C3 N4 nanosheets provide nanochannels for water transport while bigger molecules are retained. The self-supported nanochannels in the g-C3 N4 membrane are very stable and rigid enough to resist environmental challenges, such as changes to pH and pressure conditions. Permeation experiments and molecular dynamics simulations indicate that a novel nanofluidics phenomenon takes place, whereby water transport through the g-C3 N4 nanosheet membrane occurs with ultralow friction. The findings provide new understanding of fluidics in nanochannels and illuminate a fabrication method by which rigid nanochannels may be obtained for applications in complex or harsh environments.
Keywords: g-C3N4 nanosheets; membranes; self-supporting structures; separation; ultralow friction.
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