On the kinetics of the nitrate reduction in concentrated nitric acid

The autocatalytic mechanism involved in the reduction reaction of nitrate in 8 M nitric acid solution was investigated in order to propose a complete description of all processes taking place at the interface. A time and potential independent current plateau was observed for low scan rates and was ascribed to limitation by the desorption of NOads. Data analysis and fit of the experimental chronoamperogram allowed determination of the kinetic constants of the autocatalytic cycle.

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► The investigation of the autocatalytic mechanism of the reduction of concentrated nitric acid on platinum is reported.
► A simplified mechanism involving adsorbed intermediate was shown to accurately describe the the chronoamperometric response.
► It is demonstrated that desorption of NO limits the current to the nevertheless extremely high value of 1 A.cm− 2.