Electrochemical Quartz Crystal Microbalance Monitoring of the Cyclic Voltammetric Deposition of Polyaniline. A Laboratory Experiment for Undergraduates

2007 ◽  
Vol 84 (4) ◽  
pp. 681 ◽  
Author(s):  
Qingji Xie ◽  
Zhili Li ◽  
Chunyan Deng ◽  
Meiling Liu ◽  
Youyu Zhang ◽  
...  
Keyword(s):  
Laboratory Experiment ◽  
Quartz Crystal Microbalance ◽  
Quartz Crystal ◽  
Electrochemical Quartz Crystal Microbalance ◽  
Cyclic Voltammetric

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

2003 ◽  
Vol 68 (9) ◽  
pp. 1579-1595 ◽  
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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