H₂-Evolving Dye-Sensitized Photocathode Based on a Ruthenium–Diacetylide/Cobaloxime Supramolecular Assembly

The development of NiO-based molecular photocathodes is attracting more interest in the field of dye-sensitized photoelectrochemical cells for efficient conversion of sunlight into fuel. For this purpose, different strategies are developed to assemble the molecular components together to build functional devices. Here, an original dye/catalyst supramolecular assembly was designed and obtained via axial coordination of a cobalt-based H2-evolving catalyst, i.e., a cobaloxime complex, to a pyridyl-functionalized ruthenium–diacetylide photosensitizer. The new supramolecular assembly was successfully employed for the construction of efficient NiO-based photocathodes for solar hydrogen production. We report a joint experimental and theoretical study of the new photocatalytic system, including electrochemical and X-ray photoelectron spectroscopy analyses. Photoelectrochemical generation of H2 under pertinent aqueous conditions eventually led to a faradaic efficiency of 27%.