Copper(I) Bis(diimine) Sensitized Titania Nanotube Array Photoelectrodes for Photoelectrochemical Water Oxidation

Dye-sensitized photoelectrochemical cells (DS-PECs), devices inspired by photosynthesis, are being developed to advance the goal of using the sun as the sole source of energy for converting abundant resources to fuel and valuable chemicals. Herein, we report using compact and vertically aligned titanium dioxide nanotubes as semiconducting materials functionalized with a molecular copper(I) bis(diimine)-based donor-chromophore-acceptor to yield a photoanode capable of carrying out oxidative processes. Surface characterization and photoelectrochemical studies point to the nanotubes being intrinsically sensitized with carbon impurities for visible light absorption. The ability of unfunctionalized and dye-sensitized photoanodes to drive oxidative processes is further confirmed photoelectrochemically and in the presence of a water oxidation catalyst where a Faradaic efficiency of 84% is found for oxygen production.