Effect of tin ions on the electroreduction of nitrate anions on platinized platinum electrodes

Electroreduction of nitrate anions in sulfuric-acid solutions is studied on Pt/Pt electrodes in the presence of Sn2+ ions in solution and on electrodes preliminary modified by tin adatoms. It was found that, in both cases, the activity of platinum in electroreduction of NO3- in a wide potential region increases almost by two orders of magnitude. This effect is substantially stronger than those observed earlier in the presence of germanium adatoms. It is shown that hydroxylamine is the main product of electroreduction. The electrodes modified by tin adatoms are found to gradually lose their surface activity when polarized in a certain potential region in solutions containing NO3-. It is shown that there are certain differences in the behavior of electrodes preliminary modified by tin and electrodes in contact with solutions containing Sn2+ and NO3-. Possible mechanisms of the process are discussed.