Stabilization of Ruthenium(II) Polypyridyl Chromophores on Mesoporous TiO2 Electrodes: Surface Reductive Electropolymerization and Silane Chemistry

Stabilization is a critical issue in the long term operation of dye-sensitized photoelectrosynthesis cells (DSPECs) for water splittingor CO2 reduction. The cells require a stable binding of the robust molecular chromophores, catalysts, and chromophore/catalyst assemblies on metal oxide semiconductor electrodes under the corresponding (photoelectro)chemical conditions. Here, an efficient stabilization strategy is presented based on functionalization of FTO|nanoTiO2 (mesoporous, nanostructured TiO2 deposited on fluorine-doped tin oxide ( FTO) glass) electrodes with a vinylsilanefollowed by surface reductive electropolymerization of a vinyl-derivatized Ru(II) polypyridyl chromophore. The surface electropolymerization was dominated by a grafting-through mechanism, and rapidly completed within minutes. Chromophoresurface coverages were controlled up to three equivalent monolayers by the number of electropolymerization cycles. The silane immobilization and cross-linked polymer network produced highly (photo)...