Synthesis of [Ru3(μ3-NPh)(Br)(CO)9]− on self-assembled monolayers of di(3-aminopropyl)viologen/ITO surfaces and its application to photoelectrochemical cells

Triruthenium carbonyl clusters {[Ru3(Br)(CO)11]− (denoted as Ru-1), [Ru3(μ2-Br)(CO)10]− (denoted as Ru-2), and [Ru3(μ3-NPh)(Br)(CO)9]− (denoted as Ru-3)} were synthesized on di(3-aminopropyl)viologen (DAPV)/indium tin oxide (ITO) using a surface reaction in a ruthenium (III) carbonyl [Ru3(CO)12] solution, and were applied to photoelectrochemical cells (PECs) at the molecular level. The formation of DAPV on ITO was realized in the form of self-assembled monolayers. Ru3(CO)12 then easily reacted with the Br− of DAPV, and a mixture of Ru-1 and Ru-2 was formed on DAPV/ITO. Furthermore, Ru-3 was successfully anchored on DAPV/ITO by adding nitrosobenzene in order to react with Ru-2 on DAPV/ITO. The photocurrents of (Ru-1 and Ru-2)/DAPV/ITO and Ru-3/DAPV/ITO in PECs at the molecular level were 6.3 nA cm−2 and 8.6 nA cm−2, respectively. The quantum yield of Ru-3/DAPV/ITO was ∼0.8%. Time-resolved photoluminescence spectroscopy and emission spectroscopy were recorded to bring out the photoinduced charge transfer process from ruthenium clusters to DAPV.