Investigating Light-Driven Hole Injection and Hydrogen Evolution Catalysis at Dye-Sensitized NiO Photocathodes: A Combined Experimental–Theoretical Study

Dye-sensitized photoelectrochemical cells form an emerging technology for the large-scale storage of solar energy in the form of (solar) fuels because of the low cost and easy processing of their constitutive photoelectrode materials. Such hybrid photoelectrodes consist of molecular dyes grafted onto transparent semiconducting metal oxides in combination with catalytic centers. The optimization of the performances of such hybrid photoelectrodes requires a detailed understanding of the light-driven electron transfer processes occurring first at the interface between the semiconducting material and the dye and then between the dye and the catalytic center. Here we address the first of these issues and use quantum chemistry to determine the structural and electronic features of the interfaces between a push-pull dye and the p-NiO (100) surface. We show that these calculations are in good agreement with transient absorption spectroscopic measurements on a prototypical dye-sensitized photocathode system able to evolve hydrogen in the presence of a cobaloxime catalyst in solution.