Photocatalytic H₂ Evolution Using a Ru Chromophore Tethered to Six Viologen Acceptors

A new photo-charge separator (PCS) consisting of a [Ru(bpy)₃]²⁺ (bpy=2,2′-bipyridine) chromophore and six viologen (MV²⁺) acceptors, [Ru(bpyMV2)₃]¹⁴⁺, is synthesized and its application in the photocatalytic H₂ evolution reaction is reported. The present PCS possesses shorter linkers for connecting the Ru chromophore and the MV²⁺ acceptors in comparison with our previous PCSs (Inorg. Chem. Front., 2016, 3, 671–680) and shows a consecutive photo-driven electron transfer in the presence of a sacrificial electron donor [ethylenediaminetetraacetic acid (EDTA)], leading to a multi-electron storage over the PCS. This behavior can also be coupled with the catalytic H₂ evolution by the presence of a colloidal Pt catalyst. More importantly, the present PCS exhibits a much higher durability during the photolysis, which is attributed to the higher rate in the catalytic process. The high durability is also attributed to its bulky framework preventing undesirable side reactions.