Intensification of the nitrate anion reduction on a membrane palladium electrode

Polarization curves of electroreduction of nitrate anions in sulfuric acid aqueous solutions on a Pd/Pd palladium electrode with the opposite side kept at different constant potentials in the region of Pd-H α-phase formation are compared. The reduction rate of nitrate anions is shown to be substantially higher on a membrane electrode, provided the conditions of hydrogen supply from the membrane's opposite side to the reaction zone are realized. This phenomenon is caused by the reduction of a chemisorbed intermediate (a certain N(III) form) by hydrogen diffused through the membrane. It is shown that the measurements of hydrogen diffusion currents through a membrane can be used in plotting hydrogen sorption isotherms in the Pd-H α-phase.