A solid-state sensor based on tris(2,2′-bipyridyl)ruthenium(II)/poly(4-aminodiphenylamine) modified electrode: Characterization and applications

A solid-state sensor based on poly(4-aminodiphenylamine) film deposited at glassy carbon electrode doped with tris(2,2′-bipyridyl)Ru(II) complex (Padpa/Ru/GCE) was constructed electrochemically. The surface morphology of the film modified electrode was characterized using electrochemical and surface scanning techniques. A redox property represented by [Ru(bpy)3]3+/2+ couple immobilized at the Padpa moiety was characterized using typical voltammetric techniques. The XPS data demonstrated the existence of (N) bonding responsible for polymer formation while the degree of polymerization is reduced by the presence of components containing chloride ions, specifically (NH3+Cl−) which is expected to rule the linkage of Padpa with Ru-complexes. The AFM image reveals a broken and fused Padpa/Ru fiber structure compared to a relatively uniform Padpa film. Parameters such as electron transfer coefficient, surface concentration, roughness and energy dissipation were estimated. Primarily, the modified electrode was applied as an environmental sensor for the simultaneous determination of Zn2+, Cd2+, Pb2+ and Cu2+ ions in water samples. The detection limits for these metal ions were dropped to 122.5, 21.7, 9.8 and 28.0 ppb, respectively.