Morphology, microstructure and electrocatalytic properties of activated copper surfaces

Abstract

Alterações morfológicas em superfícies de cobre resultantes da aplicação de um protocolo definido de potencial foram examinadas por microscopia eletrônica de varredura (MEV) e microscopia de força atômica (AFM). Os resultados mostraram uma boa correlação entre o tempo empregado na ativação do eletrodo, microestrutura resultante e a atividade eletroquímica.Morphologic changes on copper surfaces upon applying an established potential protocol were examined by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The results showed a good correlation between the time employed in the electrode activation and the resulting microstructure and electrochemical activity.Keywords: nitrite, copper electrode, activation process, SEM, AFM IntroductionThe deliberate manipulation of electrodic surfaces consists of an area of continuing interest, because this approach leads to an improvement in the ability to recognize molecules and carry out electron transfer processes at higher rates. Hence, one of the dominant subjects in electrochemistry is the attempt to control the chemical composition and morphological structure of the electrode surface to gain advantages in electroanalytical determinations. It is well known that the electroactivity of copper surfaces depends strongly on their morphology, surface area and structure, which would in turn depend on the method employed to prepare the electrode prior to electrochemical measurements. Hence, several studies have been reported in the literature on the use of copper surfaces aiming for the quantification of different species such as glucose, 1 carbohydrates, 2 ethanol, 3 nitrate, 4, 5 nitrite, 5 and sufite. 6 The electrochemical determination of nitrate after deposition of copper from solutions containing Cu(II) has been reported by some authors, 7,8 who examined qualitatively the morphology of the copper deposit by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The increased sensitivity for nitrate after the surface modification by deposition of the fresh copper layer was attributed to morphologic changes assessed through quantitative parameters such as roughness and porosity of the film. Our group reported a new procedure for the activation of copper surfaces using a potential protocol based on copper oxidation and subsequent reduction of generated copper ions. 9,10 Taking into account these findings and as an attempt to understand which surface parameters control the electrochemical activity, the present study aims to evaluate whether there is a quantitative correlation between the surface area of copper electrodes and their electrochemical properties. Accordingly, copper electrodes were activated for different periods of time to produce layers which were analyzed by SEM and AFM. Then, the electrochemical activity of each generated surface was evaluated towards the cathodic reduction of nitrite. To the best of our knowledge, this is the first time that such a quantitative approach is applied for copper electrodes. Experimental Chemicals a...

Using an Activated Copper Microelectrode for Voltammetric Determination of Alcohols

“…Аналогичного результата можно достичь, используя другую стратегию, когда активация медного электрода осуществляется с помощью ряда стадий окисления/восстановления (анодное растворение меди и последующее переосаждение окисленного материала) без использования растворов для меднения [24]. Впервые данный способ был применен при катодном восстановлении нитритов на медном электроде: он позволил в значительной степени повысить чувствительность и точность анализа за счет регулирования состава и структуры электродной поверхности в контролируемых условиях [25,26].…”