Electrooxidation of hydrazine catalyzed by 4-hydroxy-2,2,6,6-tetramethyl-piperidinyloxy (TEMPOL)

The electrocatalytic oxidation of hydrazine (N₂H₄) by TEMPOL on a glassy carbon electrode has been studied. The kinetic parameters of the electrode reaction were measured and the electrocatalytic reaction mechanism for the electrooxidation of hydrazine in the presence of TEMPOL was proposed. TEMPOL undergoes a reversible single electron transfer process at a glassy carbon electrode (GCE) at pH 1.2–8.0, and the electrochemical oxidation of N₂H₄ at a GCE can be catalyzed by TEMPOL. The catalytic current is affected by the concentration of catalyst and pH. The overall number of electrons involved in the catalytic oxidation of N₂H₄ and the number of electrons involved in the rate determining step (rds) are 4 and 1, respectively. The catalytic oxidation obeys the first-order kinetics with respect to N₂H₄. The proposed mechanism is consistent with the experimental data, and a cation intermediate > N---O---N₂H₄⁺], formed by reaction of oxoammonium salt with N₂H₄, is involved in the reaction.