To overcome these limitations, the Chinese group led by Wen Liping used nanofibers from natural silk and polyethyleneimine to decorate 2D nanosheets. Inspired by the biological structure in nature, the 2D nanosheets were self-assembled layer-by-layer to form a nacre-like stacked structure. The composited membrane then acted as an ion-gating heterojunction with opposite charges and asymmetrical nanochannels.
According to Wen, the composited membrane shows higher toughness than other reported materials and natural nacre structures. The membrane is also able to efficiently control interlayer spacing and achieve stable ordered nanostructures.
“The typical brick-and-mortar structure formed by nanofibers and nanosheets exhibits a long-time use in solutions. Meanwhile, the confined dehydration and charge-exclusion effects conduct Li+through composited channels rapidly,” Wen said in a media statement. “Experimental and theoretical results indicate Li+ shows an excellent permeation rate that is far higher than Na+, K+, Mg2+ and Ca2+ due to its small radius and low charge. Compared with mobilities in bulk, Li+ remains basically consistent with the bulk value.”
The expert said that the methodology of using tailor-made 2D membranes with chemical, geometrical, and electrostatic heterostructures allows further exploration of nanofluidic phenomena inside nanochannel membranes for water treatment or power generation.
