Composite Graphite-Epoxy Electrodes for In Situ Electrochemistry Coupling with High Resolution NMR

Autor(es)

da Silva, Pollyana Ferreira ; Gomes, Bruna Ferreira ; Silva Lobo, Carlos Manuel ; Carmo, Marcelo ; Roth, Christina ; Colnago, Luiz Alberto

• Tipo de documento: Artigo Científico
• Fonte: ACS OMEGA; v. 7, n. 6, p. 10-pg., 2022-01-31.

Resumo

The in situ coupling between electrochemistry and spectrometric techniques can help in the identification and quantification of the compounds produced and consumed during electrochemical reactions. The combination of electrochemistry with nuclear magnetic resonance is quite attractive in this respect, but it has some challenges to be addressed, namely, the reduction in the quality of the NMR signal when the metallic electrodes are placed close to or in the detection region. Since NMR is not a passive technique, the convective effect of the magnetic force (magnetoelectrolysis), which acts by mixing the solution and increasing the mass transport, has to be considered. In seeking to solve the aforementioned problems, we developed a system of miniaturized electrodes inside a 5 mm NMR tube (outer diameter); the working and counter electrodes were prepared with a mixture of graphite powder and epoxy resin. To investigate the performance of the electrodes, the benzoquinone reduction to hydroquinone and the isopropanol oxidation to acetone were monitored. To monitor the alcohol oxidation reaction, the composite graphite-epoxy electrode (CGEE) surface was modified through platinization. The electrode was efficient for in situ monitoring of the aforementioned reactions, when positioned 1 mm above the detection region of the NMR spectrometer. The magnetoelectrolysis effect acts by stirring the solution and increases the reaction rate of the reduction of benzoquinone, because this reaction is limited by mass transport, while no effect on the reaction rate is observed for the isopropanol oxidation reaction. (AU)

• Processo FAPESP: 21/12694-3 - Aplicações das espectroscopias de RMN e infravermelho na análise não-destrutiva de produtos e processos agroindustriais
• Beneficiário: Luiz Alberto Colnago
• Modalidade de apoio: Auxílio à Pesquisa - Regular
• Processo FAPESP: 19/13656-8 - Desenvolvimento e aplicações da ressonância magnética nuclear em produtos e processos de interesse agropecuário
• Beneficiário: Luiz Alberto Colnago
• Modalidade de apoio: Auxílio à Pesquisa - Regular
• Processo FAPESP: 12/22281-9 - Estudo por RMN do fenômeno magneto-convectivo sobre íons paramagnéticos durante eletrodeposição
• Beneficiário: Bruna Ferreira Gomes Lobo
• Modalidade de apoio: Bolsas no Brasil - Doutorado Direto