A Chinese research team used graphene oxide to test photo-induced active (anti-gradient) ion transport in 2D layered materials. “It provides a completely new way for remote, non-invasive, and active control of the transport behaviors in synthetic membrane materials.”

“Researchers from the Chinese Tsinghua University and CAS demonstrated a coupled photon-electron-ion transport phenomenon through graphene oxide membranes. Using the energy of light, cations are able to move thermodynamically uphill over a broad range of concentrations, at rates orders of magnitude faster than that via simple diffusion.
 
Based on this mechanism, the team further developed 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.
 
The team stated that this is the first discovery of photo-induced active (anti-gradient) ion transport in 2D layered materials with extraordinarily high pumping rates. It provides a completely new way for remote, non-invasive, and active control of the transport behaviors in synthetic membrane materials.
 
In addition, the light-induced active ion transport reported in this work does not rely on lipid or liquid membranes, which significantly improves its robustness and compatibility. In addition, it does not hinge on specific ion-binding shuttle molecules to achieve the trans-membrane ion transport. Thus, its transport range can be centimeter-long.”

The paper was published in Nature “Photo-induced ultrafast active ion transport through graphene oxide membranes

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.

Chinese researchers achieve photo-induced ultrafast active ion transport through graphene oxide membranes.”
 
Source: Alerts

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