“ Hydroxamates as Robust , Conductive Anchors for Semiconductor Oxide Surfaces

Working in the Yale Solar Group (YSG PIs: Batista, Brudvig, Crabtree, Schmuttenmaer) in the Chemistry Dept., we have introduced a more robust anchor to attach molecular components to semiconductor oxide surfaces such as to TiO2 nanoparticles (n-TiO2). The goal of the YSG, generation of fuels from solar-driven water splitting, required that the dye and catalyst components be attached to the n-TiO2 electrode in a way that resists hydrolytic release yet allows passage of electrons. Inspired by the well known ability of hydroxamates to act as high affinity ligands for Fe in siderophores (Fe scavenger molecules secreted by microorganisms), we expected that they would also bind to Ti(IV) at the n-TiO2 surface. This proved well founded and a variety of experiments has established the robustness of linkage and its ability to transmit electrons. Most notably an MK2 dye sensitized solar cell with a conventional carboxylate anchor, easily degraded by humidity, was replaced with a hydroxamate anchor; the modified cell proved not only to be robust but even to work better in the presence of water. If time permits, some recent results on water oxidation catalysts may be presented.