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Electrocatalysis of Nitrate Reduction at Copper‐Nickel Alloy Electrodes in Acidic Media
Author(s) -
Simpson Brett K.,
Johnson Dennis C.
Publication year - 2004
Publication title -
electroanalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.574
H-Index - 128
eISSN - 1521-4109
pISSN - 1040-0397
DOI - 10.1002/elan.200302790
Subject(s) - electrode , nickel , copper , cyclic voltammetry , alloy , cathodic protection , adsorption , inorganic chemistry , electrochemistry , electrocatalyst , materials science , analytical chemistry (journal) , chemistry , metallurgy , chromatography
The cathodic reduction of NO $\rm{ {_{3}^{-}}}$ in 1.0 M HClO 4 is investigated by voltammetry at pure Ni and Cu electrodes, and three Cu‐Ni alloy electrodes of varying composition, all configured as rotated disks. Voltammetric data obtained using these hydrodynamic electrodes demonstrate significantly improved activity for NO $\rm{ {_{3}^{-}}}$ reduction at Cu‐Ni alloy electrodes as compared to the pure Ni and Cu electrodes. This observation is explained on the basis of the synergistic benefit of different surface sites for adsorption of H‐atoms, generated by cathodic discharge of H + at Ni‐sites, and adsorption of NO $\rm{ {_{3}^{-}}}$ at Cu‐sites on these binary alloy electrodes. Koutecky‐Levich plots indicate that the cathodic response for NO $\rm{ {_{3}^{-}}}$ at a Cu 75 Ni 25 electrode corresponds to an 8‐electron reduction, which is consistent with production of NH 3 . In comparison, the cathodic response at Cu 50 Ni 50 and Cu 25 Ni 75 electrodes corresponds to a 6‐electron reduction, which is consistent with production of NH 2 OH. Flow injection data obtained using Cu 50 Ni 50 and Cu 25 Ni 75 electrodes with 100‐μL injections exhibit detection limits for NO $\rm{ {_{3}^{-}}}$ of ca. 0.95 μM (ca. 95 pmol) and 0.60 μM (ca. 60 pmol), respectively.