Polymer Chromophore-Catalyst Assembly for Solar Fuel Generation

A polystyrene-based chromophore-catalyst assembly (poly-2) has been synthesized and assembled at a mesoporous metal oxide photoanode. The assembly contains water oxidation catalyst centers based on [Ru(trpy) (phenq)]²⁺ (Ru-Cat) and [Ru(bpy)₃]²⁺ derivatives (Ru-C) as chromophores (trpy= 2,2′6,2″-terpyridine, phenq = 2-(quinol-8′-yl)-1,10-phenanthroline and bpy = 2,2′-bipyridine). The photophysical and electrochemical properties of the polychromophore-oxidation catalyst assembly were investigated in solution and at the surface of mesoporous metal oxide films. The layer-by-layer (LbL) method was utilized to construct multilayer films with cationic poly-2 and anionic poly(acrylic acid) (PAA) for light-driven photochemical oxidations. Photocurrent measurements of (PAA/poly-2)₁₀ LbL films on mesoporous TiO₂ demonstrate light-driven oxidation of phenol and benzyl alcohol in aqueous solution. Interestingly, illumination of (PAA/poly-2)₅ LbL films on a fluorine doped SnO₂/TiO₂ core/shell photoanode in aqueous solution gives rise to an initial photocurrent (â=18.5 μA·cm^-2) that is in part ascribed to light driven water oxidation.