Effect of tin ions on the electroreduction of nitrate anions on platinizedplatinum 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 electrode s preliminary modified by tin adatoms. It was found that, in both cases, th e activity of platinum in electroreduction of NO3- in a wide potential regi on increases almost by two orders of magnitude. This effect is substantiall y stronger than those observed earlier in the presence of germanium adatoms . It is shown that hydroxylamine is the main product of electroreduction. T he electrodes modified by tin adatoms are found to gradually lose their sur face activity when polarized in a certain potential region in solutions con taining NO3-. It is shown that there are certain differences in the behavio r of electrodes preliminary modified by tin and electrodes in contact with solutions containing Sn2+ and NO3-. Possible mechanisms of the process are discussed.