Graphene Foam Interdigitated Microband Arrays: [Fe(CN)6]3-/4- Generator-Collector Redox Processes and Prussian Blue Catalyst Attachment

Abstract

Graphene foam based interdigitated microband array electrodes with typically 400 μm width and 150 μm inter-electrode gap (10 anodes and 10 cathodes, each 5.8 mm long; active array area 63.5 mm²) were produced on polyimide substrates and investigated for electrochemical performance. The one-electron reversible aqueous Fe(CN)₆^3-/4- redox system is employed in the presence and in the absence of 0.1 M KNO₃ supporting electrolyte. Voltammetric responses on graphene foam suggest essentially reversible electron transfer under diffusion control with solution resistivity/migration contributing to the peak-to-peak separation especially in the absence of added electrolyte. Under bipotentiostatic control, generator-collector feedback current signals are recorded with a signal hysteresis (affected by solution resistivity) consistent with a relatively wide inter-electrode gap. With a positive potential bias during repetitive cyclic voltammetry, Prussian blue deposits/electrocatalysts form on the graphene foam. Generator-collector processes for combined oxygen reduction-hydrogen peroxide oxidation are observed.