Linear sweep voltammetry is an electrochemical technique commonly used to study redox reactions. It involves linearly changing the potential of a working electrode while measuring the resulting current. This allows determination of redox potentials and analysis of reaction kinetics. Linear sweep voltammetry of the reversible ferrocene redox couple is presented as a demonstration, showing the characteristic anodic peak and dependence on parameters like concentration and scan rate. The technique has various applications in areas like analytical chemistry, sensor development, and battery research.

1. Department of Chemistry
Electrode Processes and Kinetics (CHM-513)
Assignment No. 02
Linear Sweep Voltametry (LSV)
Submitted to: Dr. Jaweria Ambreen
Submitted by:
Qamir Ullah
CIIT/FA22-R06-050/ISB

2. Linear Sweep Voltammetry
Linear sweep methods are the most common electrochemical methods in use by chemists
today.They provide an efficient and straightforward assessment of the redox behavior of
molecular systems.In all potential sweep methods, the potential (V, volts) of the working
electrode is varied continuously with time according to a predetermined potential waveform
(aka excitation function), while the current (I, amps) is concurrently measured as a function of
the potential.The applied potential at the working electrode is measured against a reference
electrode of choice, while a counter (aka auxiliary) electrode is required to balance the I-V
applied.
Thus, three electrodes are required:
► working electrode
► reference electrode
► counter electrode
An electrolyte salt must also be dissolved in solution to maintain sufficient conductivity in the bulk
solution and maintain diffusion controlled mass transfer at the electrode interface.

3. Common electrodes
Working electrode
► Glassy carbon
► Platinum
► Silver
► Gold
Counter electrode
► Pt wire
► Glassy carbon rod
Reference electrode
(physically but not electrochemically
isolated with a porous vycor frit)
► Ag/AgCl 3 M aq. KCl
► Normal Hydrogen Electrode (NHE)
► Satura ted Calomel Electrode
► Ag/AgNO3 (0.01 M in 0.1 M Bu4NPF6 acetonitrile)

4. Working Principle
Linear sweep voltammetry represents the most basic potential sweep method.In LSV the potential of the
working electrode is varied linearly with time between two values i.e., the initial (Ei) and final (Ef)
potentials.As the electrode potential is constantly rising (or decreasing) throughout the experiment, a level
of capacitive (aka Ohmic) current flows continuously. These currents are due to the capacitive charging of
the working electrode's double layer.
Faradaic current will also flow when the potential reaches a value at which the species in solution
can undergo electrochemical conversions.
Excitation function (potential waveform) for a LSV experiment

5. Practical Applications:
Here are some practical applications of linear sweep voltammetry:
i. Determination of Redox Potentials: LSV is widely employed to measure the redox potentials of
electroactive species. By sweeping the potential linearly while monitoring the current response, the
redox potential of a species can be identified as the potential at which the current exhibits a significant
change. This information is crucial for understanding the thermodynamics and kinetics of redox
reactions.
ii. Electrochemical Kinetics: LSV allows the determination of reaction kinetics by observing the current
response as a function of the applied potential. By analyzing the shape and magnitude of the current-
time curve, important kinetic parameters such as the rate constant, electron transfer coefficient, and
reaction mechanism can be extracted.
iii. Analytical Chemistry: LSV is employed in various analytical techniques, including the detection and
quantification of analytes in solution. It can be used for voltammetric stripping analysis (VSA) and
anodic stripping voltammetry (ASV), which are sensitive methods for trace metal analysis. LSV is also
utilized in the determination of organic compounds, pharmaceuticals, and environmental pollutants.
iv. Sensor Development: LSV is an essential tool for the development of electrochemical sensors. By
immobilizing selective recognition elements on the electrode surface, LSV can be used to investigate the
electrochemical behavior of analytes and their interactions with the recognition elements.
v. Electrode Surface Characterization: LSV provides valuable information about the behavior and
properties of electrode surfaces. By studying the current response during potential scanning, insights
can be gained into electrode processes, surface reactions, adsorption phenomena, and the
electrochemical stability of materials.
vi. Battery and Energy Storage Research: LSV is employed in the characterization and analysis of battery
materials and energy storage systems. It can be used to investigate the electrochemical behavior of
electrode materials, measure the capacity and cycling performance of batteries, study the kinetics of
charge transfer processes, and optimize the design of energy storage devices.

6. Linear sweep voltammetry of ferrocene
• The FeIII/II
couple of ferrocene, (η5
-C5H5)2Fe, is an example of an electrochemically reversible
system in acetonitrile solution and is often used as an internal or pseudo reference when
reporting formal potentials of inorganic and organometallic complexes.
• For example, taking a 1 mM solution of ferrocene under the following conditions:
► Working electrode = 2 mm diameter platinum disc
► Counter electrode = Pt wire
► Reference electrode = Ag/AgCl 3 M aq. KCl
► Electrolyte = 0.1 M Bu4NPF6 in acetonitrile
• The voltammetric scan is started at a potential at which no electrochemical reactions may take
place, that is, V < < E  (at least 177 mV).
• Scanning the potential linearly in the positive direction gives rise to a Faradaic current upon
oxidation of the Fe(II) center to Fe(III).
• Importantly, the solution is kept quiescent, i.e. not stirred, so that diffusion is the only mass
transport mechanism possible.
• If the redox couple is electrochemically reversible a characteristic anodic wave is observed
with a maximum current value given by the Randles-Sevcik equation.

7. 0
b
a
-5 f i
pa
e
c
-10 anodic
Excitation function for a LSV experiment
d
E
pa
0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1
Potential (V) vs. Ag/AgCl
1 mM ferrocene (2 mm Pt disc; 0.1 M Bu4NPF6 acetonitrile; Pt wire; Ag/AgCl 3M aq. KCl)
Linear sweep voltammetry of ferrocene
Randles-Sevcik equation (at 25 C):
ip = peak current; n = # electrons;
A = electrode area; C = concentration; v = scan rate
Current
(

A)

8. Linear sweep voltammetry of ferrocene
a. The initial potential at 0.10 V shows no current and therefore no electrolysis when the electrode
is switched on.
b. The electrode is scanned toward a more positive potential.
c. As the potential is made more positive the electrode is now a sufficiently strong oxidant to oxidize
the ferrocene to ferrocenium.
d. The concentration of ferrocene
decreases rapidly at the electrode
surface as the anodic current increases.
At point d the concentration of ferrocene
is substantially diminished causing the
current to peak.
e. The current now decays as the ferrocene
concentration becomes more depleted
and ferrocenium surrounds the electrode.
f. Complete oxidation is ensured by
scanning to 0.75 V.
0
-5
-10
0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1
Potential (V) vs. Ag/AgCl
b
a
f i
pa
e
c
anodic
d
E
pa
Current
(

A)

9. Important notes on LSW
• Note: Epa does not equal the standard reduction potential of the corresponding redox couple.
• For reversible one-electron redox couples the anodic peak Epa occurs at ca. 30 mV more positive
than E and its position is independent of the scan rate, whereas the cathodic peak Epc occurs ca.
30 mV more negative of E.
• For a revesible redox couple, the position of both Epa and Epc are independent of the scan rate but
i  v1/2
.
• If the voltammogram exhibits an irreversible peak, the corresponding peak potential will shift
anodically for Epa as the scan rate increases.
Refrences :
 Bard, A. J., & Faulkner, L. R. (2020). Electrochemical methods: Fundamentals and applications (2nd ed.).
Wiley.
 Kissinger, P. T., & Heineman, W. R. (2020). Laboratory techniques in electroanalytical chemistry (2nd
ed.). CRC Press.
 Wang, J. (2016). Analytical electrochemistry (3rd ed.). Wiley-VCH.
 Švorc, Ľ., & Labuda, J. (Eds.). (2019). Linear sweep voltammetry: Measuring and interpreting results.
Springer.
 Compton, R. G., & Banks, C. E. (Eds.). (2020). Understanding voltammetry (2nd ed.). Imperial College
Press.
 Ewing, A. G., Bigelow, J. C., Wightman, R. M. (2022). Electrochemical methods for neuroscience. CRC
Press.