Electrochemical Oxidation of Ammonia on Ir Anode in Potential Fixed Electrochemical Sensor

Ir catalyst possesses a good electrocatalytic activity and selectivity for the oxidation of NH₃ and/or NH₄OH at Ir anode in the potential fixed electrochemical sensor with the neutral solution. Owing to the same electrochemical behavior of NH₃ and NH₄OH in a NaClO₄ solution, NH₄OH can be used instead of NH₃ for the experimental convenience. It was found that the potential of the oxidation peak of NH₄OH at the Ir/GC electrode in NaClO₄ solutions is at about 0.85 V, and the current density of the oxidation peak of NH₄OH is linearly proportional to the concentration of NH₄OH. The electrocatalytic oxidation of NH₄OH is diffusion-controlled. Especially, Ir has no electrocatalytic activity for the CO oxidation, illustrating that CO does not interfere in the measurement of NH₄OH and the potential fixed electrochemical NH₃ sensor with the neutral solution, and the anodic Ir catalyst possesses a good selectivity. Therefore, Ir may have practical application in the potential fixed electrochemical NH₃ sensor with the neutral solution.