The mechanism of oxidation of copper in alkaline solutions

Chialvo, María R. Gennero de; Marchiano, S. L.; Arvía, Alejandro Jorge

doi:10.1007/bf00618735

Cited by 146 publications

(72 citation statements)

References 11 publications

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“…The be havior of cop per in neu tral and al ka line so lu tions has been stud ied by several au thors [1][2][3][4][5][6][7][8][9][10][11] . There ex ists a general agree ment about the struc ture and com position of prepassive and pas sive films, al though the ki net ics of complex an odic pro cesses can change de pending on po ten tial perturbations, the na ture of ions in so lution [4][5][6][7]9,11 , ionic strength, pH, and hy dro dy namic con di tions [5][6][7][8] .…”

Section: Introductionmentioning

confidence: 99%

The effects of temperature and pH on the dissolution and passivation processes of copper in carbonate-bicarbonate solutions

Ribotta¹,

Folquer²

1997

J. Braz. Chem. Soc.

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Foram feitos estudos eletroquímicos de eletrodos de cobre policristalino em soluções de carbonato-bicarbonato, analisando os efeitos da temperatura e do pH, cobrindo uma extensa faixa de composições eletrolíticas num intervalo de 5-65 °C. As condições hidrodinâmicas do sistema também foram consideradas. Os resultados são explicados com base numa modificação das características do filme decorrente dos efeitos de agitação da solução e das temperaturas elevadas. Nestas situações, forma-se uma camada menos hidratada, reduzindo o processo de dissolução. A força iônica torna-se um fator adicional que afeta o estado geral do sistema.Elec tro chem i cal stud ies of polycrystalline cop per elec trodes in car bon ate-bicarbonate solu tions an a lyz ing both tem per a ture and pH ef fects were car ried out, cov er ing a wide range of elec tro lyte com po si tion in the 5-65 °C range. Hy dro dy namic con di tions were also con sid ered. The re sults are ex plained on the ba sis of a mod i fi ca tion of the char ac ter is tics of the film through so lu tion stir ring and high tem per a ture. In this sit u a tion, a less hy drated pas sive layer is obtained, re duc ing the dis so lu tion pro cess. The ionic strength be comes an ad di tional fac tor that af fects the gen eral state of the sys tem. Key words: cop per, pH, tem per a ture, voltammetry In tro duc tionThe be havior of cop per in neu tral and al ka line so lu tions has been stud ied by several au thors [1][2][3][4][5][6][7][8][9][10][11] . There ex ists a general agree ment about the struc ture and com position of prepassive and pas sive films, al though the ki net ics of complex an odic pro cesses can change de pending on po ten tial perturbations, the na ture of ions in so lution [4][5][6][7]9,11 , ionic strength, pH, and hy dro dy namic con di tions [5][6][7][8] . The aim of this study was to at tain in for ma tion about the potentiodynamic be hav ior of cop per in so lu tions containing car bon ate/bi car bon ate ions, cov ering wide ranges of elec trolyte pH, tem per a ture, and ionic strength, in or der to es tab lish their con tri bu tions to the metal dis so lu tion and passivation pro cesses. Ma te rials and MethodsThe elec trochemical equip ment, ex perimental de tails and elec trode treat ment have been pre vi ously de scribed in de tail 7,12 . "Specpure" cop per ro tat ing disks (John son Matthey Chem i cals., 0.15 cm 2 ap par ent area) em bedded in PTFE hold ers were used as the work ing elec trodes.The potentials were measured against a saturated calomel electrode (SCE), but in the text the potential are re ferred to the NHE scale, tak ing into ac count the corrected po ten tial val ues of SCE ac cording to a suit able equation 13 . A large-area plat i num plate was em ployed as the coun ter elec trode.The elec tro lyte so lu tions con sisted of a mix ture of xM KHCO 3 + yM K 2 CO 3 (0.0075 ≤ x ≤ 2.25; 0.0005 ≤ y ≤ 1.5), cov er ing the 8.3-11.6 pH range. They were prepared from an a lyt i cal grade re agents and tri ple-distilled wa ter pre vi ously bo...

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Section: Introductionmentioning

confidence: 99%

The effects of temperature and pH on the dissolution and passivation processes of copper in carbonate-bicarbonate solutions

Ribotta¹,

Folquer²

1997

J. Braz. Chem. Soc.

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“…As shown in Figure 4a, cyclic voltammogram measurements in pure sodium hydroxide solution shows a slight increase in the current density in a region from 100 mV to 400 mV versus Hg/HgSO4, which can be explained by a partial oxidation as well as the formation of mixed hydroxides of the cuprite material [28]. Furthermore, it has been described that, at potentials more than 400 mV versus Ag/AgCl, an oxidation of Cu 2+ to Cu 3+ occurs [29], while the cathodic peak can be attributed to the reduction of Cu 3+ .…”

Section: Amperometric Sensing Performance Of Glucosementioning

confidence: 91%

Facile wet-chemical synthesis of differently shaped cuprous oxide particles and a thin film: Effect of catalyst morphology on the glucose sensing performance

Neetzel

Muench

Matsutani

et al. 2015

Sensors and Actuators B: Chemical

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In this work, different facile synthesis routes were developed to create cuprite-based catalyst systems for the amperometric detection of glucose, allowing us to evaluate the impact of important electrode fabrication parameters on the glucose sensing performance. Using homogenous precipitation routes based on a redox system, two differently shaped cuprite particles-skeletons and polyhedrons-could be obtained. Furthermore, a novel electroless deposition technique was introduced that does not require sensitization and activation pretreatments, allowing for the direct modification of the glassy carbon. This technique produced electrodes with dense thin film consisting of merged, octahedral cuprite crystals. Afterward, these materials were tested as potential catalysts for the electrochemical detection of glucose. While the catalyst powders obtained by precipitation required Nafion ® to be attached to the electrode, the thin film synthesized using electroless plating could be realized with and without additive. Summarizing the results, it was found that Nafion ® was not required to achieve glucose selectivities typically observed for cuprite catalysts. Also, the type of catalyst application (direct plating versus ink drop coating) and the particle shape had a pronounced effect on the sensing performance. Compared to the thin film, the powder-type materials showed significantly increased electrochemical responses. The best overall performance was achieved with the polyhedral cuprite particles, resulting in a high sensitivity of 301 µA . mmol -1 cm -2 , a linear range up to 298 µmol . L -1 and a limit of detection of 0.144 µmol . L -1 .2

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“…22,23 Using locally built electrochemical cells and instrumentation, it is possible to make such measurements while one face of the quartz-crystal is in an electrolytic solution and under potential control, allowing the in situ investigation of the mechanical impedance of the various copper oxide species electrodeposited onto the electrode surface. [24][25][26] Literature 27 on this subject covers both kinetics and structural aspects, even though some apparent discrepancy still remains, especially in the case of the participation of a Cu(III) species in electrocatalytic processes.…”

Section: Instrumentationmentioning

confidence: 99%

EQCM behavior of copper anodes in alkaline medium and characterization of the electrocatalysis of ethanol oxidation by Cu(III)

Paixão

Ponzio

Torresi

et al. 2006

J. Braz. Chem. Soc.

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A oxidação anódica de eletrodos de cobre em meio alcalino foi investigada utilizando-se voltametria, cronoamperometria, medidas de impedância eletroacústica e microbalança eletroquímica de cristal de quartzo (MECQ). Os experimentos foram realizados em soluções de NaOH na faixa de concentração de 0,1 a 3,0 mol L -1 . A formação de espécies solúveis e insolúveis como Cu(OH) 4 2-and Cu 2 O durante o processo de dissolução eletroquímica foi caracterizada por estudos potenciodinâmicos e pela análise das relações entre massa e carga. Por outro lado, os resultados obtidos utilizando a MECQ não foram satisfatórios para confirmar a natureza das espécies de cobre propostas na literatura como CuO e Cu(OH) 2 , visto que há mudanças viscoelásticas do filme eletrodepositado sobre o cristal de quartzo. A participação de espécies solúveis de Cu(III) no processo eletrocatalítico de oxidação do etanol foi caracterizada pelas medidas obtidas com a MECQ. Com estes dados foi possível propor um modelo para explicar o processo eletródico envolvendo a oxidação do etanol na superfície de cobre.The anodic oxidation of copper electrodes in alkaline solutions was investigated by using voltammetry, chronoamperometry, impedance measurements and the electrochemical quartz crystal microbalance (EQCM). Experiments were carried out in NaOH solutions in the 0.1 to 3.0 mol L -1 concentration range. The formation of soluble and insoluble species such as Cu(OH) 4 2-and Cu 2 O during the electrodic dissolution of copper anodes was characterized by analyzing potentiodynamic mass responses and the relationship between mass changes and charge. On the other hand, EQCM data were not effective to confirm the nature of other copper species proposed in literature named as CuO and Cu(OH) 2 because of viscoelastic changes in the film layer electrodeposited onto the quartz crystal. The participation of a Cu(III) soluble species in the electrocatalytic oxidation of ethanol was proved by EQCM measurements, data providing valuable information on the mechanism of the electrode process and formation of a Cu(II) insoluble species from the reaction of Cu(III) with ethanol.

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The mechanism of oxidation of copper in alkaline solutions

Cited by 146 publications

References 11 publications

The effects of temperature and pH on the dissolution and passivation processes of copper in carbonate-bicarbonate solutions

The effects of temperature and pH on the dissolution and passivation processes of copper in carbonate-bicarbonate solutions

Facile wet-chemical synthesis of differently shaped cuprous oxide particles and a thin film: Effect of catalyst morphology on the glucose sensing performance

EQCM behavior of copper anodes in alkaline medium and characterization of the electrocatalysis of ethanol oxidation by Cu(III)

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