Visible-Light-Driven Photocatalytic Water Oxidation by a π-Conjugated Donor–Acceptor–Donor Chromophore/Catalyst Assembly

The organic chromophore 2,2′-(benzo[c][1,2,5]thiadiazole-4,7-diyl)bis(thiophene-3-carboxylic acid), T2-BTD, was prepared and investigated along with metal complex [Ru(bda)(pyP)2] (bda = 2,2′-bipyridine-6,6′-dicarboxylate; pyP = 3-(pyridine-4-yloxy)propyl)phosphonic acid), RuC, for light-driven water splitting in dye-sensitized photoelectrochemical cells. The resulting co-loaded organic chromophore plus catalyst surface assembly was evaluated by photocurrent transient measurement and direct O2 detection using a collector–generator cell. The complete SnO2/TiO2 core–shell-based photoanode exhibited an enhanced photocurrent (∼38 μA cm–2) compared to that with only the chromophore (∼24 μA cm–2). A modest Faradaic efficiency of 12% was recorded for O2 generation under 1 sun illumination in pH 3.9, 0.1 M acetate buffer solutions.