2D Heterostructured Nanofluidic Channels for Enhanced Desalination Performance of Graphene Oxide Membranes.

Wu, Yuying; Fu, Cen-Feng; Huang, Qiang; Zhang, Pengpeng; Cui, Peng; Ran, Jin; Yang, Jinlong; Xu, Tongwen · ACS Nano · 2021

basic_science · Level V

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Abstract

The two-dimensional (2D) lamellar membrane assembly technique shows substantial potential for sustainable desalination applications. However, the relatively wide and size-variable channels of 2D membranes in aqueous solution result in inferior salt rejections. Here we show the establishment of nanofluidic heterostructured channels in graphene oxide (GO) membranes by adding g-C<sub>3</sub>N<sub>4</sub> sheets into GO interlamination. Benefiting from the presence of stable and sub-nanometer wide (0.42 nm) GO/g-C<sub>3</sub>N<sub>4</sub> channels, the GO/g-C<sub>3</sub>N<sub>4</sub> membrane exhibits salt rejections of ∼90% with water permeances of above 30 L h<sup>-1</sup> m<sup>-2</sup> bar<sup>-1</sup>, while the pure GO membrane only has salt rejections of below 30% accompanied by water permeances of below 4 L h<sup>-1</sup> m<sup>-2</sup> bar<sup>-1</sup>. Combining experimental and theoretical investigations, size exclusion has proved to be the dominating mechanism for high rejections, and the ultralow friction water flow along g-C<sub>3</sub>N<sub>4</sub> sheets is responsible for permeation enhancements. Importantly, the GO/g-C<sub>3</sub>N<sub>4</sub> membrane shows promising long-term, antioxidation, and antipressure stability.