Spectrocyclic Voltammetry of Ruthenium Purple Electrodeposited on a WO3/Tris(2,2′-bipyridine)-ruthenium(II)/Polymer Hybrid Film
Abstract
Summary: Electrochemical reactions of Ruthenium purple, Feequation/tex2gif-stack-1.gif[RuII(CN)6]3 (RP; FeIII-RuII) were studied using a spectrocyclic voltammetry (SCV) technique. The SCV measurement for an RP film coated on an ITO electrode showed a reversible redox between RP and Ruthenium white (RW; FeII-RuII) at 0.14 V vs saturated calomel reference electrode (SCE). An RP film was electrodeposited on a hybrid film of tungsten trioxide (WO3)/tris(2,2′-bipyridine)ruthenium(II) ([Ru(bpy)3]2+; bpy = 2,2′-bipyridine)/poly(sodium 4-styrenesulfonate) (PSS) (denoted as WRP film) from a colloidal solution containing 0.5 mM FeCl3, 0.5 mM K4[Ru(CN)6] and 40 mM KCl using a potentiodynamic multi-sweep technique. In a cyclic voltammogram (CV) of a WRP/RP film, a redox response was observed at 0.61 V in addition to essential redox responses of WRP hybrid film (a [Ru(bpy)3]2+/[Ru(bpy)3]3+ redox at 1.03 V and a HxWO3/WO3 redox below 0.09 V), but a redox response of RW/RP was not observed at 0.14 V. The SCV measurement for the WRP/RP film suggested that the redox response at 0.61 V is attributed to a redox of [Ru(bpy)3]2+/[Ru(bpy)3]3+ interacted electrostatically with RP. It also showed that RW is oxidized to RP via [Ru(bpy)3]2+/[Ru(bpy)3]3+ redox and RP is reversibly reduced to RW via HxWO3/WO3 redox. This unique geared electrochemical reaction for the WRP/RP film leads to a hysteresis property of an RW/RP redox.
