Photoelectrodes for solar water splitting utilizing cheap and abundant materials are being developed at the Laboratory of Photonics and Interfaces at EPFL. In PECHouse2 we advanced earth-abundant metal oxide photoelectrodes based on iron oxide and cuprous oxide toward photoelectrochemical (PEC) water splitting applications, in addition to pursuing a number of new high-performance materials. We achieved unassisted sunlight-driven water splitting in several different device configurations, further advancing the technology toward commercial viability. Theoretical understanding of the underlying physical processes and their optimization for efficient solar water splitting is being studied at the Institute of Computational Physics, ZHAW. Numerical simulations based on our electrical model helped to understand energetic band alignment of iron oxide and cuprous oxide photoelectrodes and their photocurrent-voltage response. Electrical models with charge transfer from valence band or surface states, a controversial topic discussed in the recent literature, were compared by impedance spectroscopy response. Detailed optical characterization and modeling allowed us to spectrally resolve all optical loss channels for iron oxide.
