Mechanism studies of hydrazine electro-oxidation by a platinum ultramicroelectrode: Effects of supporting electrolytes

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The effects of the supporting electrolyte on electro-catalytic reaction of hydrazine hydrate (HH) were studied by a platinum ultramicroelectrode. We found that the H+ electric field generated during the catalytic process can partly hinder the reactants from participating in the catalytic reaction by using low concentration supporting electrolytes. It results in the final steady current value is less than the theoretical value. On the other hand, supporting electrolyte has a regulatory effect on both concentrations of N2H4 and N2H5+ (protonated HH) involved in catalytic reaction, which in turn affects the number of steady state currents and the value of each steady state current generated in the reaction. In this case, the effect of neutral salts did not change with concentration variations. By contrast, when different concentrations of sulfuric acid or sodium hydroxide are used as the electrolytes, the number of steady state currents and the value of each steady state current are mainly determined by the original and the later produced H+ concentration around the electrode; while the number of steady state current and the value of each steady state current are co-determined by the thermodynamic equilibrium and the thermodynamics of catalytic reaction of HH, and the H+ absorbability of solution with different concentrations and types of sodium phosphate buffer. Moreover, this work can also provide useful information for the choice of supporting electrolyte and catalytic potential in determination of HH concentration by amperometric method and in catalytic reaction with HH as the redox medium.