Electrochemical reduction of nitrate on Pt(S)[n(1 1 1) × (1 1 1)] electrodes in perchloric acid solution |
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Authors: | Satoshi Taguchi Juan M Feliu |
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Affiliation: | Departament de Quimica Fisica, Universidad de Alicante, Apartado 99, Spain |
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Abstract: | The electrochemical reduction of nitrate ion was studied by cyclic voltammetry on Pt(1 1 1) and n(1 1 1) × (1 1 1)] stepped Pt surfaces, where n (=14, 10, 7, 6, 5, 4, 3, 2) is the number of terrace atoms, in 0.1 M HClO4 + 10 mM KNO3. The electrocatalytic nitrate reduction was found to hardly proceed on Pt(1 1 1) in the hydrogen adsorption region, while the electrocatalytic activity was improved with the increase in the step density. Inactivation was observed in the presence of adsorbed hydrogen or nitrate-derived reduced adsorbate, i.e. adsorbed NO, on (1 1 1) step sites. It was, therefore, concluded that the electrocatalytically active NO3− species does not adsorb on the (1 1 1) terraces but on the (1 1 1) monoatomic steps. The nitrate reduction current increased with the step density in a non-linear relationship. The overall current density at 0.21 V (RHE) corresponding to the peak potential of the main electrocatalytic nitrate reduction wave which was maximum at n = 2, abruptly increased with short terraces, i.e. n < 5, where the current wave of adsorbed hydrogen on the Pt stepped surface with comparatively narrow (1 1 1) terraces, denoted as Hnt, also appeared unmodified for n < 5 on voltammograms recorded in 0.1 M HClO4 in the absence of nitrate. |
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Keywords: | Nitrate reduction Stepped single crystal platinum electrodes Structure-sensitive reaction Adsorbed hydrogen Electrocatalysis |
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