Role of the Metal and Surface Structure in the Electro-oxidation of Hydrazine in Acidic Media

The adsorption and oxidation of hydrazine in acidic media has been studied on single-crystal electrodes of platinum, gold, and rhodium with basal crystallographic orientations. Voltammetric and charge-displacement experiments indicate the monoelectronic adsorption of hydrazine, either reversible or irreversible, at Pt and Rh electrodes, in the low-potential region. On Au single-crystal electrodes hydrazine adsorption is weak. The electrocatalytic oxidation of hydrazine is sensitive to the nature of the metal used as anode and to its surface structure. In the absence of specific anion adsorption, hydrazine oxidation takes place on rhodium electrodes at lower potentials than on platinum and gold. Under these conditions, the highest catalytic activity is obtained with face-centered cubic (100) orientation for the three metals.