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 photo-induced active ion transport phenomenon can be also found in almost the whole family of 2D semiconductors. There is tremendous room to further exploit their photo-responsiveness in liquid processable colloidal 2D materials.