Photo-induced ultrafast active ion transport through graphene oxide membranes

Jinlei Yang,Lei Jiang,Danyan Ji,Xian Kong,Xiaoyu Hu,Di Quan,Diannan Lu,Lili Wang,Qi Wen,Wei Guo,Pan Jia,Jianzhong Wu

doi:10.1038/s41467-019-09178-x

Abstract

Layered graphene oxide membranes (GOM) with densely packed sub-nanometer-wide lamellar channels show exceptional ionic and molecular transport properties. Mass and charge transport in existing materials follows their concentration gradient, whereas attaining anti-gradient transport, also called active transport, remains a great challenge. Here, we demonstrate a coupled photon-electron-ion transport phenomenon through the GOM. Upon asymmetric light illumination, cations are able to move thermodynamically uphill over a broad range of concentrations, at rates much faster than that via simple diffusion. We propose, as a plausible mechanism, that light irradiation reduces the local electric potential on the GOM following a carrier diffusion mechanism. When the illumination is applied to an off-center position, an electric potential difference is built that can drive the transport of ionic species. We further develop photonic ion switches, photonic ion diodes, and photonic ion transistors as the fundamental elements for active ion sieving and artificial photosynthesis on synthetic nanofluidic circuits.

Highlights

Layered graphene oxide membranes (GOM) with densely packed sub-nanometer-wide lamellar channels show exceptional ionic and molecular transport properties
We propose a plausible mechanism to explain this phenomenon based on a carrier diffusion model and molecular dynamics (MD) simulations
We further develop photonic ion switches (PIS), photonic ion diodes (PID), and photonic ion transistors (PIT) as the fundamental elements for active ion sieving and artificial photosynthesis on synthetic nanofluidic circuits

Summary

Introduction

Layered graphene oxide membranes (GOM) with densely packed sub-nanometer-wide lamellar channels show exceptional ionic and molecular transport properties. Existing artificial molecular transport systems reside in lipid or liquid membranes, and use the energy of light to pump protons or metal ions through the membrane against their concentration gradients[17,18,19]. The supported liquid membranes become the bottleneck for practical applications, because they are fragile and hardly compatible with other components[20] These molecular transport systems hinge on much larger ion-binding shuttle molecules for transmembrane ion transport[21]. We further develop photonic ion switches (PIS), photonic ion diodes (PID), and photonic ion transistors (PIT) as the fundamental elements for active ion sieving and artificial photosynthesis on synthetic nanofluidic circuits

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Conclusion