On photo-enhanced transport in ionically conducting solids
Ionic conducting materials form the basis of solid oxide fuel cells, solid oxide electrolyser cells, and batteries, which form a key component of the EU Energy 2050 long-term strategy. There is a need to develop faster ionic conductors, however progress has been slow. Recently, several studies have demonstrated photo-enhanced iodine-ion diffusion as well as suggested interactions between photons and oxygen-ion defects in oxide materials may be possible. The proposed research plan, OPTICS, aims to address the question: Can changes in ion transport be enhanced in technologically relevant ionically conducting oxides (O-ion, H-ion, and Li-ion) by light illumination? 

There are challenges in studying these effects using conventional methods. Namely, absorption only occurring at the surface in thick samples, artefacts in conductivity measurements stemming from photocurrents and electrode effects, and difficulties understanding the mechanisms due to the indirect nature of photon-ion interactions. In OPTICS, these challenges will be overcome employing isotopic tracer diffusion measurements on epitaxial thin films carried out in tandem with atomistic and continuum simulations to identify the underlying mechanisms. Combining the Host’s (Prof. Roger De Souza) expertise in tracer diffusion and atomistic modelling with the Applicants experience with optical measurements on epitaxial films, photo-enhanced ionic diffusion will be studied experimentally and computationally in the bulk, at surfaces, and at interfaces of nanostructured materials. Light-enhanced ionic transport has the potential, though OPTICS, to lead to substantial improvements in technologically relevant ionic conductors leading to a new class of photo-ionic fuel cells, electrolysers, and batteries.