Covalent Design for Dye-Sensitized H2-Evolving Photocathodes Based on a Cobalt Diimine-Dioxime Catalyst.

Dye-sensitized photoelectrochemical cells (DS-PECs) for water splitting hold promise for the large-scale storage of solar energy in the form of (solar) fuels, owing to the low cost and ease to process of their constitutive photoelectrode materials. The efficiency of such systems ultimately depends on our capacity to promote unidirectional light-driven electron transfer from the electrode substrate to a catalytic moiety. We report here on the first noble-metal free and covalent dye-catalyst assembly able to achieve photoelectrochemical visible light-driven H2 evolution in mildly acidic aqueous conditions when grafted onto p-type NiO electrode substrate.