Generator-collector voltammetry at dual-plate gold-gold microtrench electrodes as diagnostic tool in ionic liquids

Ionic liquids provide high viscosity solvent environments with interesting voltammetric characteristics and new electrochemical mechanisms. Here, a gold-gold dual-plate microtrench electrode is employed in generator-collector mode to enhance viscosity-limited currents in ionic liquids due to fast feedback within small inter-electrode gaps (5μm inter-electrode gap, 27μm microtrench depth) and to provide a mechanistic diagnosis tool. Three redox systems in the ionic liquid BMIm⁺BF₄^- are investigated: (i) ferrocene oxidation, (ii) oxygen reduction, and (iii) 2-phenyl-naphthyl-1,4-dione reduction. Both transient and steady state voltammetric responses are compared. Asymmetric diffusion processes, reaction intermediates, and solubility changes in the ionic liquid are revealed.