Abstract
This paper reinvestigates the mechanism of HNO 2 and NO2- reduction on polycrystalline platinum as a function of electrolyte pH and reactant concentration. Intermediates and/or reaction products were detected by means of various (combined) techniques: RRDE (for NH 2OH detection), OLEMS (for volatile products) and FTIRS. In acidic media, HNO 2 is depleted due to homogeneous-phase reactions (accelerated by stirring) that generate NO: the latter species, which readily forms an adlayer on Pt, is reduced in a first wave to N 2O, while HNO 2 is reduced in a following diffusion-limited wave to mainly NH 2OH. The two waves display different reaction orders. Loss of HNO 2 (as NO) in the blanketing Ar stream hampered an accurate quantitative evaluation of the product distribution. When the pH is increased, NO2- is reduced in a single peak with a much lower current density than in the previous case. In RDE experiments, the peak was found to decrease with increasing rotation rates. The presence of a sluggishly reduced intermediate (NH 2OH) has been proposed. A general mechanistic scheme, including NO, HNO 2 and NO2-, is discussed.
Original language | English |
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Pages (from-to) | 59-68 |
Number of pages | 10 |
Journal | Journal of Electroanalytical Chemistry |
Volume | 649 |
Issue number | 1-2 |
DOIs | |
Publication status | Published - 15 Nov 2010 |
Keywords
- Fourier-transform infrared spectroscopy
- Nitrite
- Nitrogen cycle
- Nitrous acid
- On-line mass spectroscopy
- Ring-disk electrodes
ASJC Scopus subject areas
- Chemical Engineering(all)
- Analytical Chemistry
- Electrochemistry