(189bz) Fluid Behavior and Interfacial Structure of Heterogeneous GO Interlayer Pores

Fluid Behavior and Interfacial Structure of

Heterogeneous GO Interlayer Pores

Tongfei Yu, Shuyan Liu, Xiaoning Yang*

State Key Laboratory of Materials-Oriented Chemical Engineering,

Nanjing Tech University, Nanjing 210009, China

ABSTRACT: Water permeation through Graphene oxide (GO)-based laminate membrane has attracted increasing attention due to its great potential in nanofluidics and separation applications. However, the impact of complicated heterogeneous features of GOs on the water transport still remains largely unresolved and commonly neglected. In particular, recent various new-typed GO-based composite membranes further highlighted the importance of the hetero-structures. A comprehensive and in-depth understanding of the roles various structural features on water flow across the GO interlayer is significant and imperative for optimal design and application of GO-based membrane.

In this work, comprehensive MD simulations were performed to study the water transport and confined structure through a series of heterogeneous 2-D GO-based channels. Meanwhile, we theoretically developed a flow equation for heterogeneous 2-D channels assembled with asymmetrical GO sheets. This equation could reveal the leading role of the high-friction side of heterogeneous channels in controlling flow enhancement. By combining the MD simulation and theoretical analysis, it is found that the presence of one oxidized sheet could significantly prohibit the fast flow even though another sheet is frictionless pristine graphene, which is consistent with the theoretical prediction results. The distinct vertical drag effect stemmed from the interfacial affinity of GO surface has been revealed as the underlying mechanism, which is characterized by the asymmetric velocity profile and unique interfacial hydrogen bond behavior, as well as surface affinity. Our results provide new insight into the flow behavior between heterogeneous GO interlayer galleries and computationally reveal the unusual mechanism of the completely different water transport, as compared with that in traditional homogeneous pores. These unique understandings are not only valuable for guiding and improving the rational design of GO-based membranes, but also provide new physical pictures for heterogeneous capillary channel in extensive 2-D nanofluidics.

ACKNOWLEDGMENTS

This work was supported by the National Natural Science Foundation of China under Grants 21676136

*: Corresponding author, Yangxia@njtech.edu.cn