Electrocatalytic oxidation of phenolic compounds using an electrode modified with Ni(II) porphyrin adsorbed on SiO₂/Nb₂O₅-phosphate synthesized by the sol¨Cgel method

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• 作者：Maria Suzana P. Francisco ; ^{msuzana@lnls.br} ; William S. Cardoso ; Lauro T. Kubota ; Yoshitaka Gushikem
• 关键词：Hydroquinone and 4-aminophenol electrochemical sensor ; Biomimetic electrocatalyst ; Phosphated SiO2/Nb2O5 ; Sol&ndash ; gel method ; Ni(II) porphyrin
• 刊名：Journal of Electroanalytical Chemistry
• 出版年：2007
• 出版时间：1 April 2007
• 年：2007
• 卷：602
• 期：1
• 页码：29-36
• 全文大小：455 K

文摘

Phosphated silica¨Cniobia, , presenting high specific surface area (S_BET = 580 m² g^?) was used as substrate base to adsorb 5,10,15,20-tetrakis(1-methyl-4-pyridyl)-21-H,23-H-porphyrin and furthermore metallated with Ni(II). The adsorption of porphyrin and in situ metallation procedures with Ni(II) were accompanied by UV¨Cvisible spectroscopy and cyclic voltammetry under alkaline conditions, respectively. A carbon paste electrode of the material obtained (CPE-Ni) was used to investigate the detection of hydroquinone and 4-aminophenol by electrochemical methods in KCl supporting electrolyte solution The cyclic voltammogram corresponding to the Ni(II)/Ni(III) redox couple was recorded during 820 cycles and demonstrated exceptional high stability. CPE-Ni showed higher catalytic efficiency than the electrode whose oxidation is mediated by the semiconducting property of Nb₂O₅ (a carbon paste electrode of pure mixed SiO₂/Nb₂O₅ oxides) since the former presented the anodic peak potential for phenolic compounds at remarkably less positive potential. Hydroquinone and 4-aminophenol were detected over wide linear ranges of concentrations and with satisfactory sensitivities for both electrochemical techniques used, cyclic voltammetry and chronoamperometry. CPE-Ni exhibited an excellent operational response even after 260 and 280 measurements, respectively for hydroquinone and 4-aminophenol.