In situ Fourier transform infrared spectroscopic studies of nitrite reduction on platinum electrodes in perchloric acid

Nitrous oxide generated by the electrochemical reduction of nitrite on a polycrystalline platinum electrode in aqueous 0.1 M HClO4 was monitored by in situ potential difference Fourier transform infrared reflection absorption spectroscopy, An analysis of the intensity of the N2O asymmetric stretch band at 2231 cm(-1), A(N2O), monitored during a slow linear potential (E) sweep in the range 0.8 > E > -0.32 V vs SCE, indicated that N2O begins to form at E similar to 0.5 V vs SCE, reaches a maximum at E similar to 0.05 V, and disappears completely for E < -0.1 V, These observations are in agreement with those made by on-line mass spectrometry (MS) using high-area Pt electrodes in acid electrolytes reported in the literature. In addition, a plot of A(N2O) vs E was found to be directly correlated with that of the integral of the N2O generation rate, as measured by on-line dynamic differential electrochemical MS (DEMS) by Nishimura et al, (Electrochim. Acta 1991, 36, 877) in sulfuric acid solutions.