ELECTROCHEMICAL OXIDATION OF AMMONIA IN ALKALINE-SOLUTIONS - ITS APPLICATION TO AN AMPEROMETRIC SENSOR

The electrochemical oxidation of ammonia was studied at room temperatu re on a black platinum electrode, iridium black, a mixture of both and Pt-Ir electrodeposits in alkaline solutions of potassium hydroxide. T he current density for the ammonia discharge was proportional to the a mmonia concentration in the range from 50 to 200 ppm of the functionin g of the sensor. It was found that the current density on the platinum -iridium mixture is higher than on platinum black and iridium black. O n the other hand, Pt-Ir electrodeposits on Au and Pt were prepared and characterized by X-ray analysis. The diffractograms evidenced the pre sence of a continual platinum-iridium solid solution where platinum is replaced by iridium atoms in the fee structure. The Pt-Ir electrodepo sits showed a good response to the ammonia gas. (C) 1997 Elsevier Scie nce Ltd.