Large-scale synthesis of crystalline g-C3N4 nanosheets and high-temperature H2 sieving from assembled films

摘要

Poly(triazine imide) (PTI), a crystalline g-C 3 N 4 , hosting two-dimensional nanoporous structure with an electron density gap of 0.34 nm, is highly promising for high-temperature hydrogen sieving because of its high chemical and thermal robustness. Currently, layered PTI is synthesized in potentially unsafe vacuum ampules in milligram quantities. Here, we demonstrate a scalable and safe ambient pressure synthesis route leading to several grams of layered PTI platelets in a single batch with 70% yield with respect to the precursor. Solvent exfoliation under anhydrous conditions led to single-layer PTI nanosheets evidenced by the observation of triangular g-C 3 N 4 nanopores. Gas permeation studies confirm that PTI nanopores can sieve He and H 2 from larger molecules. Last, high-temperature H 2 sieving from PTI nanosheet–based membranes, prepared by the scalable filter coating technique, is demonstrated with H 2 permeance reaching 1500 gas permeation units, with H 2 /CO 2 , H 2 /N 2 , and H 2 /CH 4 selectivities reaching 10, 50, and 60, respectively, at 250°C.