Nitrogen-doped nanoporous graphene induced by a multiple confinement strategy for membrane separation of rare earth

Rare earth separation is still a major challenge in membrane science. Nitrogen-doped nanoporous graphene (NDNG) is a promising material for membrane separation, but it has not yet been tested for rare earth separation, and it is limited by multi-complex synthesis. Herein, we developed a one-step, facile, and scalable approach to synthesize NDNG with tunable pore size and controlled nitrogen content using confinement combustion. Nanoporous hydrotalcite from Zn(NO3)(2) is formed between layers of graphene oxide (GO) absorbed with phenylalanine via confinement growth, thus preparing the sandwich hydrotalcite/phenylalanine/GO composites. Subsequently, area-confinement combustion of hydrotalcite nanopores is used to etch graphene nanopores, and the hydrotalcite interlayer as a closed flat nanoreactor induces two-dimensional space confinement doping of planar nitrogen into graphene. The membrane prepared by NDNG achieves separation of Sc3+ from the other rare earth ions with excellent selectivity (similar to 3.7) through selective electrostatic interactions of pyrrolic-N, and separation selectivity of similar to 1.7 for Tm3+/Sm3+.

Automated summary

A one-step, facile, and scalable approach was developed to synthesize nitrogen-doped nanoporous graphene with tunable pore size and controlled nitrogen content. The membrane prepared by this method achieved excellent selectivity for separating Sc3+ from other rare earth ions and a separation selectivity of Tm3+/Sm3+ of approximately 1.7.