Electric-field-induced ionic sieving at planar graphene oxide heterojunctions for miniaturized water desalination

Qi Wen, Pan Jia, Liuxuan Cao, Jipeng Li, Di Quan, Lili Wang, Yanbing Zhang, Diannan Lu, Lei Jiang, Wei Guo

Research output: Contribution to journalArticleResearchpeer-review

60 Citations (Scopus)

Abstract

Layered graphene oxide membranes (GOMs) offer a unique platform for precise sieving of small ions and molecules due to controlled sub-nanometer-wide interlayer distance and versatile surface chemistry. Pristine and chemically modified GOMs effectively block organic dyes and nanoparticles, but fail to exclude smaller ions with hydrated diameters less than 9 Å. Toward sieving of small inorganic salt ions, a number of strategies are proposed by reducing the interlayer spacing down to merely several angstroms. However, one critical challenge for such compressed GOMs is the extremely low water flux (<0.1 Lm−2 h−1 bar−1) that prevents these innovative nanomaterials from being used in real-world applications. Here, a planar heterogeneous graphene oxide membrane (PHGOM) with both nearly perfect salt rejection and high water flux is reported. Horizontal ion transport through oppositely charged GO multilayer lateral heterojunction exhibits bi-unipolar transport behavior, blocking the conduction of both cations and anions. Assisted by a forward electric field, salt concentration is depleted in the near-neutral transition area of the PHGOM. In this situation, deionized water can be extracted from the depletion zone. Following this mechanism, a high rejection rate of 97.0% for NaCl and water flux of 1529 Lm−2 h−1 bar−1 at the outlet via an inverted T-shaped water extraction mode are achieved.

Original languageEnglish
Article number1903954
Number of pages8
JournalAdvanced Materials
Volume32
Issue number16
DOIs
Publication statusPublished - 23 Apr 2020
Externally publishedYes

Keywords

  • 2D layered materials
  • heterostructures
  • ion transport
  • nanofluidics
  • water desalination

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