Preparation, characterization and electrocatalytic properties of polynuclear mixed-valent ruthenium oxide/hexacyanoruthenate film modified electrodes

摘要

Polynuclear mixed-valent ruthenium oxide/ruthenocyanide (ruthenium oxide/hexacyanoruthenate or mvRuO/RuCN) films were prepared using consecutive cyclic voltammetry directly from the mixing of Ru~~(3+) and Ru(CN)_6~(4-) ions from solutions of two divalent cations (Ba~~(2+) and Ca~~(2+)), and seven monovalent cations (H~+, Li~+, Na~+, K~+, Rb~+, Cs~+, and Ga~+). The films exhibited three redox couples with Ba(NO_3)_2 or BaCl_2 aqueous solutions, and the formal potentials of the redox couples showed a cation and pH effect. An electrochemical quartz crystal microbalance (EQCM), cyclic voltammetry, UV–visible spectroscopy, and the stopped-flow method (SFM) were used to study the growth mechanism of the mvRuO/RuCN films. The results indicated that the redox process was confined to the immobilized ruthenium oxide/ruthenocyanide. The EQCM results showed a Ba~~(2+) ion exchange reaction for the two most negative redox couples. The electrocatalytic reduction properties of SO_5~(2-), and S2O82? by the ruthenium oxide/ruthenocyanide films were determined. The electrocatalytic oxidation of NADH and dopamine were also determined, and revealed two different types of properties. The electrocatalytic oxidations of SO_3~(2-), S_2O_3~(2-), and N_2H_4 were also investigated. The electrocatalytic reactions of the ruthenium oxide/ruthenocyanide films were investigated using the rotating ring-disk electrode method.