3D Photoelectrochemical imaging in porous light-addressable structures

Electrochemical imaging techniques are powerful tools for the investigation of topography, charge and catalytic activity of surfaces and can also be used for functional, label-free imaging of cellular processes with high resolution. In electrochemical applications such as energy harvesting and storage devices, these techniques can be used to investigate local currents on complex electrode surfaces, thereby aiding the development of new and efficient electrode materials. In biology, electrochemical imaging has been used to carry out detailed investigations into the transport of molecules into or out of living cells, changes in cell morphology in response to stimulation and charges and action potential of cells. However, current electrochemical imaging technologies have been limited to probing thin films or the outer surfaces of materials or living cells.

Recently, there has been a strong move towards 3D structures in both electrocatalysis and biology. Complex porous electrode structures have been developed for energy production and storage devices such as photocatalytic water splitting, redox flow batteries, fuel cells, batteries, supercapacitors and electrolysers. Detailed information about the local kinetics of electrochemical processes within pores of different shapes, sizes and interconnectivity and local effects of liquid and gas exchange during continuous operation could inform the development of novel electrode materials, but is not accessible to current electrochemical techniques. Cell biology has been swiftly moving from 2D cell culture to more complicated systems such as 3D tissue culture where complex physiological processes are investigated in an environment that resembles that of natural tissue, such as in organ-on-a chip devices, leaving the electrochemical imaging techniques behind to play catch-up. Only the outer surface of 3D structures and cells has been accessible to electrochemical scanning probe techniques, while photoelectrochemical techniques have been entirely limited to 2D imaging of flat substrates.

In this project we aim to develop a photoelectrochemical imaging system that can be used for the mapping of electrochemical processes in three dimensions within porous electrode structures. The new technology is expected to aid the development of novel electrode materials for energy harvesting and storage devices and be suitable for in-situ 3D functional imaging in 3D tissue culture to contribute to the growing research area of organ-on-a chip devices, which aims to speed up the development of new treatment strategies and the discovery of new drugs for a vast range of diseases, while at the same time reducing the need for animal experiments.