Reaction pathways for reduction of nitrate ions on platinum, rhodium, and platinum-rhodium alloy electrodes

Journal Article · Tue Jan 25 04:00:00 UTC 2000 · Langmuir

DOI:https://doi.org/10.1021/la990638s· OSTI ID:20015186

De Souza, J P.I.; Nart, F C

The reduction of nitrate ions on platinum, rhodium, and platinum-rhodium alloy electrodes has been investigated using differential electrochemical mass spectrometry and in situ FTIR measurements. For 3 M HNO{sub 3} concentration it has been found that nitrate starts the reduction with partial N-O bond dissociation and N-N bond formation generating NO and N{sub 2}O. At potentials lower than 0.2 V the reaction proceeds forming dissolved NH{sub 4}{sup +}. For potentials lower than 0 V the reduction continues via a multiple pathway reaction leading to the nonselective production of N{sub 2}, NH{sub 2}OH, and N{sub 2}H{sub 2}. On the alloyed electrodes, the production of NO and N{sub 2}O has been observed in both cathodic and anodic scans, while on pure platinum and rhodium electrodes the reaction has been observed only during the cathodic scan. Contrasting with the pure platinum and rhodium alloys, where the N-O bond break starts forming NO and N{sub 2}O, on the alloys HNO{sub 2} has been observed as the first reaction step. For alloys with higher rhodium composition, like Pt{sub 75}Rh{sub 25}, no N{sub 2} has been detected for potentials lower than 0 V.

• Research Organization: Univ. de Sao Paulo (BR)
• OSTI ID: 20015186
• Journal Information: Langmuir, Journal Name: Langmuir Journal Issue: 2 Vol. 16; ISSN LANGD5; ISSN 0743-7463
• Country of Publication: United States
• Language: English

Related Subjects

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES
54 ENVIRONMENTAL SCIENCES
ELECTRIC POTENTIAL
ELECTRODES
ELECTROLYSIS
NITRATES
PLATINUM
RADIOACTIVE WASTE PROCESSING
REDUCTION
RHODIUM