Heterogeneous catalysts: Ruthenium phthalocyanine-modified graphite electrode.

摘要

The electrochemical properties of dinuclear (Rupc)₂ species is described. The solution cyclic voltammetry of (RUPc)₂ displays a series of metal localized processes. A Pourbaix diagram describes the various surfaces, which can be generated by exposing a graphite electrode modified with (RUPc)₂ to aqueous buffer at different polarization over a wide range of pH. The behavior of these various surfaces towards the electrocatalytic reduction of oxygen, hydrogen peroxide, nitrite, hydroxylamine, and oxidation of hydrazine and hydroxylamine is described.; Three different regimes of hydrogen peroxide reduction are observed dependent on the nature of the modified electrode surface. At high pH, the four electron reduction of oxygen to water is observed via a 2 + 2 mechanism. The major products of nitrite reduction are ammonia and nitrous oxide, while Hydroxylamine is observed as a minor product. Two electron reduction of Hydroxylamine to ammonia, and two electron oxidation of hydroxylamine to nitrous oxide are observed. The four electron oxidation of Hydrazine to nitrogen is only observed at pH > 8.; Using RDE, RRDE and CV techniques, the kinetics of the catalytic reactions are investigated. Suitable mechanisms are proposed through analysis of the Tafel plots and the rate equations.