Voltammetry
Group Members
Amna Khalid (F2018067027)
Sadia Nasreen (F2018067007)
Presented to
Dr. Naveen KOsar
Introduction of Voltammetry
• Electroanalytical Method
• Information about analyte is obtained by
measuring current as potential is varied[1]
• Electrolysis on microscale is done
• Smaller concentration i.e in micromolar can
be determined
Steps involved in voltammetry
• Voltage ramp is applied to electrode
• Measurement of current
• Reduction or oxidation ions in electrodes[2]
Voltammogram
The resulting plot of current versus applied
potential is termed as voltammogram
Voltammetric Cell
• It is just like an electrochemical cell
• It consist of commonly three electrodes
1. Working Electrode
2. Auxiliary Electrode
3. Reference Electrode[3]
Working
Current-Voltage Curve
Evs SCE = EVS NHE – 0.242
Decomposition Potential
• Difference in the electrode potential cathode
and anode in order for electrolysis to occur.
• Minimum
voltage
produced
electrolytic cell
• Used in the electrolysis process
from
an
Limiting Current
• Rate of charge transfer to an electrode is
increased.
• The limiting current can be approached
• When further increase in potential does not
effect the increase in current. This is termed
as limiting Current. [4]
Voltammetric Curve
Curves obtained in the graph between potential
and applied current
Types of voltammetric curve
The shape of the curves depends on
• The speed of potential variation
• Whether the solution is stirred mass transfer[5]
S-shaped Curve
• Solution is stirred or electrode is rotated
• Limiting current is constant
• S-shaped curved is obtained
Peaked Curve
• Solution is unstirred
• No mass transfer
• Peaked wave is obtained
Some Terminologies
• Polarized Electrode
• Depolarized Electrode
• Depolarizer
Two Voltammetric Waves
•
Depolarizer is oxidized then anodic current is
recorded
at potentials more positive than
decomposition potential
Applications
Measurement of
• Concentration and Activity.
• pH.
• Hardness
• Complete voltammetric cells
are referred to as sensors.[6]
References
1. Kissinger, Peter; William R. Heineman (1996-01-23). Laboratory Techniques in
Electroanalytical Chemistry, Second Edition, Revised and Expanded (2 ed.).
CRC. ISBN 0-8247-9445-1.
2. Zoski, Cynthia G. (2007-02-07). Handbook of Electrochemistry. Elsevier
Science. ISBN 0-444-51958-0
3. https://chem.libretexts.org/Under_Construction/Purgatory/Book%3A_Analytica
l_Chemistry_2.0_(Harvey)/11_Electrochemical_Methods/11.4%3A_Voltammetric
_Methods
4. Harris, Daniel C. (2016-01-01). Quantitative Chemical Analysis, Ninth Edition (9
ed.). W.H. Freeman and Company. ISBN 978-1-4641-3538-5
5. Bard, Allen J.; Larry R. Faulkner (2000-12-18). Electrochemical Methods:
Fundamentals and Applications (2 ed.). Wiley. ISBN 0-471-04372-9
6. Sanghavi, Bankim; Srivastava, Ashwini (2010). "Simultaneous voltammetric
determination of acetaminophen, aspirin and caffeine using an in situ
surfactant-modified multiwalled carbon nanotube paste electrode".