Photodriven hydrogen evolution by molecular catalysts using AlO-protected perylene-3,4-dicarboximide on NiO electrodes.

The design of efficient hydrogen-evolving photocathodes for dye-sensitized photoelectrochemical cells (DSPECs) requires the incorporation of molecular light absorbing chromophores that are capable of delivering reducing equivalents to molecular proton reduction catalysts at rates exceeding those of charge recombination events. Here, we report the functionalization and kinetic analysis of a nanostructured NiO electrode with a modified perylene-3,4-dicarboximide chromophore () that is stabilized against degradation by atomic layer deposition (ALD) of thick insulating AlO layers. Following photoinduced charge injection into NiO in high yield, films with AlO layers demonstrate longer charge separated lifetimes as characterized femtosecond transient absorption spectroscopy and photoelectrochemical techniques. The photoelectrochemical behavior of the electrodes in the presence of Co(ii) and Ni(ii) molecular proton reduction catalysts is examined, revealing reduction of both catalysts. Under prolonged irradiation, evolved H is directly observed by gas chromatography supporting the applicability of embedded in AlO as a photocathode architecture in DSPECs.