Surface-Enhanced Infrared Absorption Spectroscopic Studies of Adsorbed Nitrate, Nitric Oxide, and Related Compounds. 3. Formation and Reduction of Adsorbed Nitrite at a Platinum Electrode

The formation, potential-dependent structural change, and reduction of adsorbed nitrite at a platinum electrode were examined in 0.1 M HClO 4 and 0.1 M NaClO 4 by surface-enhanced infrared absorption spectroscopy (SEIRAS). The band assigned to the symmetric NO 2 stretch of the nitro form of nitrite appeared at around 1300 cm −1 in both solutions. The potential dependence of the spectra revealed that this adsorbed nitrite is converted to NO adsorbed at on-top, bridge, and defect sites via IR-inactive surface nitrite species. In 0.1 M HClO 4, these three adsorbed NO species were also formed during the adsorption process from the solution NO formed by the disproportionation of nitrite. In addition to the reduction via the IR-inactive surface nitrite species, a direct conversion from adsorbed nitrite to adsorbed NO was also suggested in 0.1 M HClO 4 .