Electrocatalytic oxidation of nitrite on a carbon paste electrode modified with Co(II) porphyrin adsorbed on SiO₂/SnO₂/Phosphate prepared by the sol¨Cgel method

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• 作者：William S. Cardoso ; Yoshitaka Gushikem ; ^{gushikem@iqm.unicamp.br}
• 关键词：SiO2/SnO2 mixed oxide ; Carbon paste electrode ; Nitrite sensor ; Cobalt&ndash ; porphyrin ; Chemically modified electrode
• 刊名：Journal of Electroanalytical Chemistry
• 出版年：2005
• 出版时间：15 September 2005
• 年：2005
• 卷：583
• 期：2
• 页码：300-306
• 全文大小：197 K

文摘

This paper describes the immobilization of 5,10,15,20-tetrakis(1-methyl-4-pyridyl)-21H,23H-porphyrin ion on SiO₂/SnO₂/Phosphate obtained by the sol¨Cgel processing method. The porphyrin was adsorbed on the surface of the modified material and furthermore metallized in situ with Co(II) ion. The porphyrin metallation process was followed using UV¨CVis spectroscopy by inspecting the Q bands of the free and metallated porphyrin. A carbon paste electrode modified with material containing metallated porphyrin was used to study the electro-catalytic oxidation of nitrite ions by means of cyclic voltammetry, chronoamperometry and RDE voltammetry. The modified electrode was very stable and exhibited the electro-catalytic oxidation of nitrite ions at 0.72 V vs. SCE by a two electron mechanism producing nitrate ions at pH 5.4. The kinetic parameters of the electrode reaction process were calculated; (1 ?#xA0;¦Á)n_a was 0.479, D was (5.3 ¡À 0.11) ¡Á 10^? cm s^?, and k⁰ could be determined as (5.4 ¡À 0.14) ¡Á 10^? cm s^?.