Plasmonic Photocatalysis of Urea Oxidation and Visible-Light Fuel Cells

The intense electric (E-) field associated with the localized surface plasmon resonance (LSPR) of noble-metal nanoantennas provides a rational strategy for enhancing photoinduced charge transfer in photocatalysts. Here, we demonstrate E-field-enhanced direct photocatalytic urea oxidation and a visible-light-driven direct urea fuel cell (LDUFC) with tris(bipyridine)ruthenium(II) ([Ru(bpy)(3)](2+))-enabled plasmonic nanopigments that contain a phospholipid membrane self-assembled around a Ag nanoparticle (NP) whose LSPR overlaps the [Ru(bpy)(3)](2+) metal-to-ligand charge transfer (MLCT). In the hierarchical plasmonic nanopigment design, the membrane serves as scaffold and spacer to localize [Ru(bpy)(3)](2+) in an electromagnetic "sweet spot" where substantial plasmonic enhancement of photoexcitation is achieved while strong metal-associated quenching of the reactive excited state is avoided. The demonstration of plasmon-enhanced photocatalytic urea oxidation and the implementation of the LDUFC represent important advancements toward improved light-driven waste-water treatment and efficient solar energy conversion.