Akademik Veri Yönetim Sistemi
JOURNAL OF CHEMICAL EDUCATION, cilt.87, ss.205-207, 2010 (SCI-Expanded)
The most common in situ technique used in science
laboratories is in situ spectroelectrochemistry, which focuses
primarily on the changes of transmission or absorption spectra
during the electrochemical perturbations of a system. Published
practical examples teaching the principles and applications of in
situ spectroelectrochemistry are limited (1, 2). Heineman (1)
developed several commonly used spectroelectrochemical methods
with examples of typical applications. He also developed an
electrochemical experiment describing analysis of an optically
transparent thin-layer electrode with a spectroelectrochemistry
technique (3). Similarly, there are few publications on the
teaching of the application of spectroelectrochemistry for optical
and electrochemical characterization of different electrochromic
materials (4-6). Color changes in these studies were observed by
the naked eye or proposed by spectral changes. It has been
suggested that to describe a particular color, its scientific parameters
must be identified because full-color characterization of
an electrochromic system is essential for its application. For this
purpose, an instrumental colorimetric measurement must be
applied to record the chromaticity diagram and color parameters
of a system.
The combination of reaction-oriented electrochemistry
with colorimetry in in situ electrocolorimetry allows for a more
complete analysis of electrochromic materials. While the technique
has been well developed during the last few decades, its
application in various fields of chemistry has only recently
become more widespread (7-9). There is no published practical
example of teaching the principles and applications of in situ
electrocolorimetry techniques. Thus, we developed an experiment
that characterizes the electrochromism of methyl viologen,
extensively investigated as a material for digital displays and smart
windows applications (10, 11). In this experimental procedure,
we describe the principles and applications of in situ electrocolorimetry
combined with in situ spectroelectrochemistry.
This experiment, accomplished in a 5 h laboratory period, is
one of a series of graduating-project experiments assigned to
fourth-year undergraduates in the chemical engineering department.
Each fourth-year undergraduate of our department is
required to prepare an experimental graduating project consisting
of advanced research-like experiments to improve his or her
literature skill, independent study ability, and understanding of
basic scientific research prior to the graduation-thesis program.
Depending on class size, available resources, and run-times,
this experiment can be performed as a demonstration experiment
or an experiment in the instrumental analysis or physical
chemistry lab.