Two-dimensional lamellar nanosheet membranes with intrinsic size-sieving nanopores for ultrafast hydrogen separation.

Hydrogen separation and purification are essential for the large-scale application of green hydrogen energy. Two-dimensional (2D) material-based membrane technology provides an energy-efficient approach; however, the existing 2D lamellar membranes and nanoporous membranes struggle with low permeability and complex preparation procedures. Here, we constructed 2D lamellar nanosheet membranes with intrinsic size-sieving nanopores by assembling nanoporous polymeric carbon nitride (PCN) nanosheets into a lamellar membrane. These membranes exhibit high selectivity and permeance and ease of preparation. By applying MXene as the strong interaction patch for covering and repairing defects on PCN nanosheets, the resultant membranes demonstrated an ultrahigh H2 permeance of 870 to 8046 GPU, considerable selectivity, and superior long-term stability, outperforming most current state-of-the-art membranes. Economic analysis revealed that MXene/PCN membranes achieved ultralow energy consumption and minimal membrane area demands for practical applications. This study inspires the construction of 2D lamellar membranes with intrinsic nanopores and provides a simple and scalable approach to preparing high-performance 2D nanosheet membranes for hydrogen separation.