Publications
- For water splitting, a comprehensive understanding of the underlying reaction intermediates and pathways is crucial for optimizing catalyst design. Among the most well-known active photoanodes for the oxygen evolution half-reaction are TiO2-based materials. A hole polaron, which consists of a metal-oxide distortion around trapped holes, has been suggested as a local reactive oxygen configuration. While first-principles calculations identify new electronic states in the middle of the band gap and the influence of trapped hole dynamics on transport, an assignment of hole polaron configurations to a measured spectrum has been challenging due to broad optical transitions in the visible regime. Here, we compare the excited-state absorption (ESA) for two titanium oxide materials with a similar electronic structure but differing crystal structure.