Prospects for Future Photoelectrolysis Devices: New Oxide Semiconductors and Electrode Structures

The full potential of solar energy cannot be realized unless there is method to store it and use it as fuel.   In this talk I will give both a brief historical look at the past efforts to solve this problem and provide some options and opinions about the way forward.  It is clear that materials that are stable and have the proper band gaps for an efficient photoelectrochemical water splitting device are currently unknown.  In addition these materials need to be catalytic for water oxidation or reduction reactions or have catalyst layers deposited on their surfaces.  I will discuss combinatorial methods for discovering new oxide semiconductors and solid-state catalysts that might be further optimized to be useful in a solar water splitting device.  Researchers need to focus on quickly evaluating the many new materials that will emerge from the combinatorial searches to identify a few that have the potential to be stable, efficient and inexpensive.  An example of a new semiconducting oxide containing earth abundant iron, chromium and aluminum that was discovered by an undergraduate researcher participating in the Solar Hydrogen Activity research Kit (SHArK) project will be given. Thie photoelectrochemical behaviour of this material was followed up in our laboratory and found, after optimization of the stoichiometry,  to have a high open circuit voltage for water reduction. An example of collaborations between my laboratory and other laboratories to quickly evaluate the potential of this material will be given as an example.