Formation of cuprous oxide layers in Cu(II) solutions containing gluconic acid
Tóm tắt
In accordance with thermodynamic analysis, cuprous oxide layers are formed spontaneously in the Cu|Cu(II), gluconic acid system at pH > 3.7 under open-circuit conditions. A current peak of Cu2O reduction is observed on cathodic voltammograms at ca −0.7 V, its height being dependent on the exposure time. The analysis of the charge transferred in this region yields the rate of Cu2O formation equal to 1.25 × 10−10 mol cm−2 s−1. The light perturbation of Cu electrode under open-circuit conditions results in the generation of a negative photopotential, which is indicative of n-type conductivity. The threshold wavelength is equal to ∼590 nm and is consistent with a band gap of ∼2.1 eV. Anodic photocurrents, which are observed near the open-circuit potential, decrease with cathodic polarization and change their sign at ∼0.05 V. Analysis of impedance data was performed, invoking the equivalent circuit that accounts for the two-step charge transfer. In the presence of Cu2O, some retardation of Cu(II) reduction was found to occur with a slight increase in the admittance of the double layer. The suggestion has been made that oxide layers formed in Cu(II) gluconate solutions cannot be compact and uniformly distributed over the entire electrode surface. Relevant investigations of surface morphology support this conclusion.
Tài liệu tham khảo
Pointu B, Braizaz H, Poncet P, Rousseau J (1983) J Electroanal Chem 151:65
Aruchamy A, Fujishima A (1989) J Electroanal Chem 266(397):272–125
Survila A, Kalinauskas P, Uksienė V (1993) Electrochim Acta 38:2733
Millet B, Fiaud C, Hinnen C, Sutter EMM (1995) Corros Sci 37:1903
Survila A, Kalinauskas P, Ivaškevič E, Kutner W (1997) Electrochim Acta 42:2935
Survila A, Kalinauskas P, Valsiūnas I (2002) Russ J Electrochem 38:1068
Survila A, Survilienė A, Kanapeckaitė S, Būdienė J, Kalinauskas P, Stalnionis G, Sudavičius A (2005) J Electroanal Chem 582:221
Bertocci U (1978) J Electrochem Soc 125:1598
Babić R, Metikoš-Huković M, Lončar M (1999) Electrochim Acta 44:2413
Survila A, Kalinauskas P, Survilienė A, Sudavičius A (2007) Chemija (Vilnius) 18:18
Survila A, Kanapeckaitė S, Survilienė A (2001) J Electroanal Chem 501:151
Hara M, Kondo T, Komoda M, Ikeda S, Shinohara K, Tanaka A, Kondo J, Domen K (1998) J Chem Soc, Chem Commun 3:357
DeJongh PE, Vanmaekelbergh D, Kelly JJ (2000) J Electrochem Soc 147:486
Rajeshwar K, Singh P, DuBow J (1978) Elchim Acta 23:1117
Gerischer H (1977) J Electroanal Chem 82:133
Survila A, Kalinauskas P, Uksienė V (1988) Chemija (Vilnius) 1:51
Ishizuka S, Kato S, Okamoto Y, Sakurai T, Akimoto K, Fujiwara N, Kobayashi H (2003) Appl Surf Sci 216:94
Mahalingam T, Chitra JSP, Chu JP, Sebastian PJ (2004) Mater Lett 58:1802
Rai BP (1988) Sol Cells 25:265
Nakaoka K, Ueyama J, Ogura K (2004) J Electrochem Soc 151:C661
Mahalingam T, Chitra JSP, Chu JP, Moon H, Kwon HJ, Kim YD (2006) J Mater Sci Mater Electron 17:519
Boukamp BB (1989) Equivalent circuit (EQUIVCRT.PAS). User’s manual. University of Twente, Enschede
Pourbaix M (1966) Atlas of electrochemical equilibria in aqueous solution. Pergamon, London
Bard AJ, Parsons R, Jordan J (eds) (1985) Standard potentials in aqueous solution. Marcel Dekker, New York
Survila A, Mockus Z, Kanapeckaitė S, Pileckienė J, Stalnionis G (2011) Russ J Electrochem 47:129
Survilienė A, Survila A (2002) Russ J Electrochem 38:1216
Būdienė J, Kalinauskas P, Survila A (2004) Chemija (Vilnius) 15:7
Pileckienė J, Grigucevičienė A, Survila A (2011) Chemija (Vilnius) (in press)
Survila A, Baliukienė V (2001) Chemija (Vilnius) 12:195
Macdonald JR (1987) Impedance spectroscopy. Wiley, New York
Lasia A (1999) Electrochemical impedance spectroscopy and its applications. In: Konway BE, Bocris J, White RE (eds) Modern aspects of electrochemistry, vol 32. Kluwer Academic/Plenum, New York, p 143