Anodic oxidation of hydrazine and its derivatives Part I. The oxidation of hydrazine on gold electrodes in acid solutions

Abstract

The anodic oxidation of hydrazine on gold electrodes has been studied in acid solutions (0.5–2 N H 2 SO 4 ). The electrode pretreatment consisted of electropolishing, followed by a sequence of potentials (0.90V,−0.20V) before each measurement. The Tafel slope was determined by four independent techniques (shift of the peak potential with sweep rate in linear potential sweep, foot of the current/potential curve in the same measurement, galvanostatic and steady state potentiostatic) all of which gave values in the range of 90–100 mV. The reaction order and pH effects were 0.3 and 0.8, respectively. The mechanism proposed involves fast equilibrium in the first discharge step in which an adsorbed N 2 H 3 radical is formed. Desorption of this radical with formation of N 2 H 2 in solution is believed to be rate determining. The surface coverage by N 2 H 3 radicals is intermediate and a Frumkin type adsorption isotherm is applicable, with correction for the energy of displacement of water molecules from the surface, according to the theory of Bockris et al. for electrosorption of neutral organic species.