The role of terahertz spectroscopy in relation to the goal of catalytic water photooxidation

It is well known that water photooxidation is the first step in solar photon to fuel conversion. For the last four years, a collaboration within the chemistry department at Yale University has combined synthetic expertise, computational methodology, and experimental characterization to identify optimal systems for catalytic water photooxidation. I will provide a brief overview of these efforts, and then focus on the role that terahertz (THz) spectroscopy has played. In particular, THz spectroscopy probes the timescale and efficiency of electron transfer from photoexcited "dye" molecules into a suitable substrate such as nanocrystalline TiO2. We compare our "dye" molecules which are stable in aqueous and oxidative environments with those that perform well in the role of photoelectrochemical cells (or dye-sensitized solar cells) but are not stable in aqueous environments. Using THz spectroscopy, it is also possible to disentangle the amount of photoabsorption, charge injection, and carrier transport within the nanoparticle matrix.