Fabrication of multilayer films of viologen on a glassy carbon electrode by bottom-up layer-by-layer assembly

A stable multi-layered film of phosphonylethyl viologen–zirconium was successfully fabricated on a glassy carbon (GC) electrode by bottom-up layer-by-layer assembly. Two couples of reversible redox processes of surface confined viologen were observed in cyclic voltammetry, and the peak charges linearly changed with the number of the deposited layers. It was demonstrated that the electrochemical surface pretreatment of GC electrode prior to the layer deposition significantly improved the molecular packing density of the film, which was ascribed to the increased hydrophilic interaction between phosphate group and the oxidized GC surface. The two-step one-electron redox reactions of viologen within the multilayer were also monitored by in situ spectroelectrochemical measurements.