Deposition of selenium thin layers on gold surfaces from sulphuric acid media: Studies using electrochemical quartz crystal microbalance, cyclic voltammetry and AFM

The optical properties of palladium phthalocyanine in dimethylformamide, toluene, acetonitrile, and dichloromethane solutions were studied in the visible range of energy. Palladium phthalocyanine in organic medium presented itself as a mixture of monomeric and dimeric species in equilibrium, and it was only in dichloromethane that the monomeric, non-aggregated form predominated. Palladium phthalocyanine films were prepared by casting, and studied by cyclic voltammetry and spectroelectrochemistry. The films showed an electrochromic response from blue to purple, and stability that depended on the applied potential. Electrochemical quartz crystal microbalance experiments indicated that the film exfoliates into solution after applying high values of final potentials. Raman spectroscopy was used to structurally characterize the palladium phthalocyanine film, which showed a central metal with +2 oxidation state that is not affected even when the film is oxidized.

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Selenium(IV) Electrochemistry on Silver: A Combined Electrochemical Quartz-Crystal Microbalance and Cyclic Voltammetric Investigation

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc20031579 ◽

2003 ◽

Vol 68 (9) ◽

pp. 1579-1595 ◽

Cited By ~ 14

Author(s):

Giovanni Pezzatini ◽

Francesca Loglio ◽

Massimo Innocenti ◽

Maria Luisa Foresti

Keyword(s):

Cyclic Voltammetry ◽

Quartz Crystal Microbalance ◽

Electrochemical Behavior ◽

Quartz Crystal ◽

Reduction Process ◽

Electrochemical Quartz Crystal Microbalance ◽

Potential Range ◽

Cyclic Voltammetric ◽

Scan Rate ◽

Process Of Se

The electrochemical behavior of Se(IV) on silver was investigated by cyclic voltammetry and electrochemical quartz-crystal microbalance (EQCM) measurements. As already reported in the literature, Se(IV) electrochemistry is always complex, and on silver even more, due to the formation of a compound. Our results confirm that the reduction process of Se(IV) occurs through two reaction paths, Se(IV) → Se(0) and Se(IV) → Se(-II); the product Se(-II) then reacts with Se(IV) through a comproportionation reaction. The latter step leads to red Se that, according to the literature, is the only electroactive form of Se(0). The presence of the electroactive red Se is evident both in the negative range of potentials, through the reduction Se(0) → Se(-II), and in the less negative range of potentials, through the oxidation Se(0) → Se(IV). Moreover, our measurements pointed to the formation of a deposit that never redissolves. This deposit seems to be the electroinactive gray Se. The electrochemical behavior of Se(IV) was investigated in the whole potential range accessible on silver. Our results confirm the occurrence of competitive processes whose predominance depends on the scan rate, as well as on the potential limits of voltammetry. A detailed table with the processes occurring in different potential ranges was drawn up.

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