Efficient Hydrogen Production by a Photoredox Cascade Catalyst Comprising Dual Photosensitizers and a Transparent Electron Mediator

One-directional electron transport between a photocatalyst and redox mediator is crucial for achieving highly active Z-scheme water-splitting photocatalysis. Herein, a photoredox cascade catalyst that artificially mimics the electron transport chain in natural photosynthesis was synthesized from a Pt-TiO2 nanoparticle catalyst, two photosensitizers (RuCP6 and RuP6), and a visiblelight-transparent electron mediator (HCRu). During photocatalytic hydrogen evolution in the presence of a redox-reversible electron donor, [Co(bpy)3]2+ (bpy = 2,2 '-bipyridine), the HCRu-Zr-RuCP6-Zr-RuP6@Pt-TiO2 (PRCC-1) photocatalyst exhibited the highest reported initial (1 h) apparent quantum yield (iAQY = 2.23%) of dye-sensitized TiO2 photocatalysts to date. Furthermore, PRCC-1 successfully produced hydrogen when using hydroquinone monosulfonate (H2QS-) as the hydrogen source.

Automated summary

By synthesizing a photoredox cascade catalyst, which mimics the electron transport chain in natural photosynthesis, one-directional electron transport between a photocatalyst and redox mediator was achieved, leading to highly active Z-scheme water-splitting photocatalysis. The synthesized catalyst, PRCC-1, composed of Pt-TiO2 nanoparticle catalyst, two photosensitizers (RuCP6 and RuP6), and a visible-light-transparent electron mediator (HCRu), exhibited the highest reported initial apparent quantum yield (iAQY = 2.23%) among dye-sensitized TiO2 photocatalysts to date. Moreover, PRCC-1 successfully produced hydrogen using hydroquinone monosulfonate (H2QS-) as the hydrogen source.