The groundbreaking use of polyelectrolytes to increase the efficiency of supramolecular photocatalysts in solar H2 production schemes under aqueous aerobic conditions is reported. Supramolecular photocatalysts of the architecture [{(TL)2 Ru(BL)}2 RhX2 ](5+) (BL=bridging ligand, TL=terminal ligand, X=halide) demonstrate high efficiencies in deoxygenated organic solvents but do not function in air-saturated aqueous solution because of the quenching of the metal-to-ligand charge-transfer (MLCT) excited state under these conditions. The new photocatalytic system incorporates poly(4-styrenesulfonate) (PSS) into aqueous solutions containing [{(bpy)2 Ru(dpp)}2 RhCl2 ](5+) (bpy=2,2'-bipyridine, dpp=2,3-bis(2-pyridyl)pyrazine). PSS has a profound impact on the photocatalyst efficiency, increasing H2 production over three times that of deoxygenated aqueous solutions alone. H2 photocatalysis proceeds even under aerobic conditions for PSS-containing solutions, an exciting consequence for solar hydrogen-production research.
Keywords: hydrogen; photocatalysis; polyelectrolytes; rhodium; ruthenium.
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