Novel organic–inorganic hybrid material based on tris(2,2′-bipyridyl)dichlororuthenium(II) hexahydrate and Dawson-type tungstophosphate K 7[H 4PW 18O 62]·18H 2O as a bifuctional hydrogen peroxide electrocatalyst for biosensors

Abstract

In this study, we synthesized a new hybrid material using Wells–Dawson K 7[H 4PW 18O 62]·18H 2O (PW 18) and tris(2,2′-bipyridyl)dichlororuthenium(II) hexahydrate ([Ru(bpy) 3]Cl 2·6H 2O). CHN elemental analyses depicted that 1 mol of [H 4PW 18O 62] 7− reacts with 3 mol of [Ru(bpy) 3] 2+ to form K[Ru(bpy) 3] 3H 4PW 18O 62. By adding the mild reducing agent (KI), CHN analyses illustrated that 1 mol of [H 4PW 18O 62] 7− reacts with only 1 mol of [Ru(bpy) 3] 2+ to yield K 5[Ru(bpy) 3]H 4PW 18O 62 hybrid material. FT-IR spectra showed the presence of both [Ru(bpy) 3] 2+ cation and the Dawson anion. K 5[Ru(bpy) 3]H 4PW 18O 62 was immobilized on glassy carbon (GC) electrode and the modified electrode was subjected to cyclic voltammetry and amperometry in presence of hydrogen peroxide (H 2O 2) and found to exhibit a notable bifunctional catalytic activity towards the oxidation and the reduction of H 2O 2 at neutral pH and at reasonably low cathodic and anodic potentials. Reductive determination was found to be more efficient than the oxidative detection. The resulting H 2O 2 sensor K 5[Ru(bpy) 3]H 4PW 18O 62/GC based reductive detection at −0.4 V vs. Ag/AgCl has a sensitivity of ∼0.78 μA/mM mm 2, fast response time (<5 s), low detection limit (<0.5 μM), high selectivity towards endogenous interferences such as uric acid, acetaminophen and ascorbic acid, a linear range from 0.5 μM to at least 90 mM H 2O 2 and was stable for at least 5 weeks. This type of hybrid catalysts could be of great relevance for applications in oxidase based biosensors.