Kinetics and mechanism of the electrochemical oxidation of the NO−₂ ion on platinum in AgNO₂-acetonitrile solution

Abstract

The anodic oxidation of NO−2 ion dissolved as AgNO2 in ACN, in the range − 12° to 68°C, is investigated using platinum electrodes. Single and multiple linear potential sweep and rotating disc electrode techniques are used. The electrochemical reaction is interpreted with the following sequence of reactions: rds (1) NO₂ = NO₂ + e (2) [2 NO₂ ⇋ N₂O₄] (3) NO₂ + NO₂ = NO + NO₃ (4) NO = NO- + e (5) NO+ + NO₂ = N₂O₃ (6) [N₂O₃ ⇋ NO + NO₂] Step (1) behaves as an irreversible step which at high potentials is diffusion controlled, while step (4) corresponds to a reversible charge transfer step. The chemical reactions are fast processes. The postulated reaction mechanism for the anodic discharge of the NO−₂ ion implies the preferential reaction of the initial product with a NO−₂ ion instead of a solvent molecule as it occurred with solutions employing other aprotic solvents.