Autolab is an electrochemical measurement system consisting of a potentiostat/galvanostat and data acquisition system. It can be used to perform techniques like cyclic voltammetry and chronoamperometry. The system controls the potential or current applied to a three-electrode cell containing a working, counter, and reference electrode. Users prepare an experiment procedure specifying parameters like potential ranges and scan rates, then view and analyze the resulting electrochemical data.
in this ppt it was explained that the importance of dssc and the working principles and the notes during the research work..
the concept was explained in the ppt was very clear......
Definition of chrono potentiometry
Introduction about chrono potentiomerty
Experimental setup of chronopotentiometry
Theory of chronopotentiometry
Output wave function of chrono potentiometry
Analysis of an chronopotentiometry
Main window of chronopotentiometry
used files in chronopotentiometry
disadvantages of chronopotentiometry
Application of chrono potentiometry
compare of chronopotentiometry
Using hardware
Feature of files in chronopotentiometry
PEMFC (proton exchange membrane)
DMFC (direct methanol)
SOCF (solid oxide)
AFC (alkaline)
PAFC (phosphoric acid)
MCFC (Molten Carbonate)
PEM Fuel Cell
A fuel cell is a battery that produces DC current and voltage
Most fuel cells use hydrogen which burns cleaner compared to hydrocarbon fuels
A fuel cell will keep producing electricity as long as fuel is supplied
The energy efficiency of fuel cells is high when compared to many other energy systems
There is great interest in fuel cells for automotive and electronic applications
There will be employment for technicians particularly in Ohio’s fuel cell industry.
in this ppt it was explained that the importance of dssc and the working principles and the notes during the research work..
the concept was explained in the ppt was very clear......
Definition of chrono potentiometry
Introduction about chrono potentiomerty
Experimental setup of chronopotentiometry
Theory of chronopotentiometry
Output wave function of chrono potentiometry
Analysis of an chronopotentiometry
Main window of chronopotentiometry
used files in chronopotentiometry
disadvantages of chronopotentiometry
Application of chrono potentiometry
compare of chronopotentiometry
Using hardware
Feature of files in chronopotentiometry
PEMFC (proton exchange membrane)
DMFC (direct methanol)
SOCF (solid oxide)
AFC (alkaline)
PAFC (phosphoric acid)
MCFC (Molten Carbonate)
PEM Fuel Cell
A fuel cell is a battery that produces DC current and voltage
Most fuel cells use hydrogen which burns cleaner compared to hydrocarbon fuels
A fuel cell will keep producing electricity as long as fuel is supplied
The energy efficiency of fuel cells is high when compared to many other energy systems
There is great interest in fuel cells for automotive and electronic applications
There will be employment for technicians particularly in Ohio’s fuel cell industry.
ITO (indium tin Oxide) & FTO (fluorine doped tin oxide )Preeti Choudhary
Optical and electronic properties of ITO AND FTO:Physical properties, why use as TCOs, optical properties,electronic properties, work function and kelvin probe method and deposition technique.
The presentation is made as part of introducing some novel technologies in Chemical Engineering. It aims at conveying an overall idea about the Sol-Gel Technology, its underlying processes, applications as well as its future possibilities.
Proton Exchange Membrane Fuel Cells (PEMFC) are promising contender as the next generation energy source because of their striking features including high energy density, low operating temperature, easy scale up and zero environmental pollution.
Vergangene und gegenwärtige Sichtweisen auf das Thema SEO sind vielschichtig. Dieser hohe Anpsruch an Detailwissen macht das Thema so interessant. Diese Präse soll einen kleinen Einblick auf die unterschiedlichen Betrachtungsweisen von früher und heute ermöglichen.
ITO (indium tin Oxide) & FTO (fluorine doped tin oxide )Preeti Choudhary
Optical and electronic properties of ITO AND FTO:Physical properties, why use as TCOs, optical properties,electronic properties, work function and kelvin probe method and deposition technique.
The presentation is made as part of introducing some novel technologies in Chemical Engineering. It aims at conveying an overall idea about the Sol-Gel Technology, its underlying processes, applications as well as its future possibilities.
Proton Exchange Membrane Fuel Cells (PEMFC) are promising contender as the next generation energy source because of their striking features including high energy density, low operating temperature, easy scale up and zero environmental pollution.
Vergangene und gegenwärtige Sichtweisen auf das Thema SEO sind vielschichtig. Dieser hohe Anpsruch an Detailwissen macht das Thema so interessant. Diese Präse soll einen kleinen Einblick auf die unterschiedlichen Betrachtungsweisen von früher und heute ermöglichen.
Edita sa venuje projektovému manažmentu, vzdelávaniu a cestovaniu. Je konzultantkou na voľnej nohe a pomáha mimovládkam. Vo svojej prednáške hovorila o tom, čo to znamená budovať komunitu, o princípoch a pravidlách komunitného organizovania. Predstavila aj konkrétne príklady fungujúcich komunít.
Link na video z prednášky - https://youtu.be/Rc44mUluTl4
Jump Slovensko je neformálna konferencia o ľuďoch a pre ľudí, ktorí robia niečo pre druhých. Piaty ročník sa konal v stredu 21. septembra 2016 v Radnici v Banskej Bystrici. Organizátorom podujatia je Voices, hlavnými partnermi Nadácia Orange a Nadácia Slovenskej sporiteľne.
MATERIAL DIDÁCTICO PARA LA CLASE DE LOGÍSTICA INVERSA - UPEC 2016.
LOGÍSTICA INVERSA.- Parte de la gestión de la cadena de abastecimiento que se encarga de los flujos de retorno desde los puntos de consumo hasta los orígenes de las mercancías.
A folded floating-gate CMOS biosensor is realized for the detection of charged biochemical molecules. The biosensor comprises a field-effect transistor with a floating-gate, a control-gate, and a sensing area. Charged biochemical molecules placed on the sensing area induce a voltage on the floating-gate and a relative shift in the threshold characteristics. Compared to conventional devices, the floating-gate here is folded to span the entire device. This allows us to place the sensing area above the field-effect transistor (FET), thus reducing the total device area. The fabricated devices show good sensitivity to the polarity and concentration of charged poly amino acids. Possible applications of the device include electronic detection of spatial and temporal charge migration such as in biological processes.
A CMOS biosensor with a folded floating-gate is created to detect charged biochemical molecules. It contains a FET, a control-gate and a sensing area. The floating-gate spans the whole device, allowing the sensing area to be placed on top of the FET, resulting in a decrease of the device's total area. The device is sensitive to the polarity and quantity of charged poly amino acids and could be used for electronic recognition of temporal and spatial migration of charges, such as in biological phenomena.
B. Chen, A. Parashar and S. Pandey, "Folded Floating-Gate CMOS Biosensor for the Detection of Charged Biochemical Molecules," IEEE Sensors Journal, vol. 11, no. 11, pp. 2906-2910, Nov. 2011, doi: 10.1109/JSEN.2011.2149514.
https://ieeexplore.ieee.org/document/5762313
Today power electronics play an important role in the electric industry. Power electronic converters are an inseparable component in power systems. One of these converters is DC/AC inverter that is widely used in power systems, industrial applications, electric motor drive and electric vehicles. Due to the tense situation with the complexity that exists in these applications, inverters are exposed to failure. The fault occurring in inverter can cause disturbance and damaging harmonics, cut some industrial processes to in the power system or in the case of electric vehicles, causing irreparable damage. For this reason, detecting faults in the inverter is very important. In this paper, open circuit fault of IGBT in an electric vehicle has been examined. We use three-phase current and wavelet transform to identify the state of the system and we can extract current waveform characteristics. We use neural network algorithm for fault detection and classification. An electric vehicle in 5 different speeds and 5 different torque and a total of 220 failure modes have been studied and tested. The results show the method has been succeeded to detection all forms of defined faults.
Cyclic voltammetry readout circuitry for DNA biosensor applicationjournalBEEI
Cyclic voltammetry electrochemical biosensors reported a wide usage and applications for its fast response, able to be miniaturized and its sensitivity. However, the bulky, expensive and laboratory-based readout circuitry made it impossible to be used in the field-based environment. A miniaturized and portable readout circuitry for the DNA detection using hybridization technique had been design and developed in this work. It embedded with fabricated FR4 based sensor and produced respective current when the applied voltage was within the range of 0 to 0.5 V. The readout circuitry had been verified with five analysis environments. Bare Au with distilled water (dH2O), bare Au with ferricyanide reagent solution, DNA immobilization, DNA non-hybridization and DNA hybridization. All the results performed produced peak cathodic current when the applied input voltage is within 0.5 V to 3 V and hence proved that the miniaturized and portable readout circuitry is suitable to be implemented for cyclic voltammetry electrochemical biosensor.
At the outset we wish to thank you for the curtsey and excellent response from you and active interest in taking a comprehensive view of modern safe Lightning Protection / Earthing and the underlying scientific principles as we posted in our Linkedin Profile, which is for your ready reference.
Save energy and protect your facility with voltage optimisationNick Lee
This article will explain how voltage optimisation can
significantly reduce energy costs, reduce electrical
consumption (kWh), lower carbon emissions and
extend the lifetime of equipment whilst at the
same time protecting against harmful harmonics,
transients and correct issues related to phase voltage imbalances.
Temporary voltage swells and sags appear with high frequency in electric power systems, and they significantly affect sensitive loads such as industrial manufacturing or communication devices. This paper presents a strategy to design proportional-resonant controllers for three full-bridge voltage-source converters with a common DC-link in dynamic voltage restorer systems. The proposed controllers allow the system to quickly overcome temporary unbalanced voltage sags. Simulation results carried out in MATLAB/Simulink and experimental results implemented in a Typhoon HIL402 device demonstrate the ability of the proposed design method. The results show that the system with the proposed controllers can ride-through single-phase or double-phase voltage sags up to 55% and three-phase voltage sags up to 70% in a duration less than one grid-voltage cycle.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Analysis and Modeling of Transformerless Photovoltaic Inverter SystemsIJMER
International Journal of Modern Engineering Research (IJMER) is Peer reviewed, online Journal. It serves as an international archival forum of scholarly research related to engineering and science education.
Real time parameter estimation for power quality control and intelligent prot...EG TECHNOLOGIES
Real time parameter estimation for power quality control and intelligent protection of grid--Any details EG TECHNOLOGIES, ERODE,COIMBATORE, CHENNAI, SALEM, TIRUCHENGODE. call: 98422 38186.
The 7SR23 DAD is a numeric high impedance circulating current relay has four current inputs, it is used as a unit protection to detect phase and earth faults.
The relay can be applied to busbars, connections, transformers, reactors and motors.
Simulation and dSPACE Based Implementation of Various PWM Strategies for a Ne...IJPEDS-IAES
Depending on the number of levels in output voltage, inverters can be
divided into two categories: two level inverter and Multi Level Inverters
(MLIs). An inverter topology for high voltage and high power applications
that seems to be gaining interest is the MLI. In high power and high voltage
applications, the two level inverters have some limitations in operating at
high frequency mainly due to switching losses and constraints of device
rating.In this paper, a three phase H + type FCMLI (Flying Capacitor MLI)
using sinusoidal reference, third harmonic injection reference, 60 degree
reference and stepped wave reference are initially developed using
SIMULINK and then implemented in real time environment using dSPACE.
In H-type FCMLI with R-load it is inferred that bipolar COPWM-C
provides output with relatively low distortion for 60 degree reference
and bipolar COPWM-C strategy is found to perform better since it
provides relatively higher fundamental RMS output voltage for THI
reference. The five level output voltages of the chosen MLIs obtained using
the MATLAB and dSPACE based PWM (Pulse Width Modulation)
strategies and the corresponding %THD (Total Harmonic Distortion), VRMS
(fundamental), CF (Crest Factor) and FF (Form Factor) are presented and
analyzed.
(May 29th, 2024) Advancements in Intravital Microscopy- Insights for Preclini...Scintica Instrumentation
Intravital microscopy (IVM) is a powerful tool utilized to study cellular behavior over time and space in vivo. Much of our understanding of cell biology has been accomplished using various in vitro and ex vivo methods; however, these studies do not necessarily reflect the natural dynamics of biological processes. Unlike traditional cell culture or fixed tissue imaging, IVM allows for the ultra-fast high-resolution imaging of cellular processes over time and space and were studied in its natural environment. Real-time visualization of biological processes in the context of an intact organism helps maintain physiological relevance and provide insights into the progression of disease, response to treatments or developmental processes.
In this webinar we give an overview of advanced applications of the IVM system in preclinical research. IVIM technology is a provider of all-in-one intravital microscopy systems and solutions optimized for in vivo imaging of live animal models at sub-micron resolution. The system’s unique features and user-friendly software enables researchers to probe fast dynamic biological processes such as immune cell tracking, cell-cell interaction as well as vascularization and tumor metastasis with exceptional detail. This webinar will also give an overview of IVM being utilized in drug development, offering a view into the intricate interaction between drugs/nanoparticles and tissues in vivo and allows for the evaluation of therapeutic intervention in a variety of tissues and organs. This interdisciplinary collaboration continues to drive the advancements of novel therapeutic strategies.
Seminar of U.V. Spectroscopy by SAMIR PANDASAMIR PANDA
Spectroscopy is a branch of science dealing the study of interaction of electromagnetic radiation with matter.
Ultraviolet-visible spectroscopy refers to absorption spectroscopy or reflect spectroscopy in the UV-VIS spectral region.
Ultraviolet-visible spectroscopy is an analytical method that can measure the amount of light received by the analyte.
Richard's aventures in two entangled wonderlandsRichard Gill
Since the loophole-free Bell experiments of 2020 and the Nobel prizes in physics of 2022, critics of Bell's work have retreated to the fortress of super-determinism. Now, super-determinism is a derogatory word - it just means "determinism". Palmer, Hance and Hossenfelder argue that quantum mechanics and determinism are not incompatible, using a sophisticated mathematical construction based on a subtle thinning of allowed states and measurements in quantum mechanics, such that what is left appears to make Bell's argument fail, without altering the empirical predictions of quantum mechanics. I think however that it is a smoke screen, and the slogan "lost in math" comes to my mind. I will discuss some other recent disproofs of Bell's theorem using the language of causality based on causal graphs. Causal thinking is also central to law and justice. I will mention surprising connections to my work on serial killer nurse cases, in particular the Dutch case of Lucia de Berk and the current UK case of Lucy Letby.
This presentation explores a brief idea about the structural and functional attributes of nucleotides, the structure and function of genetic materials along with the impact of UV rays and pH upon them.
Cancer cell metabolism: special Reference to Lactate PathwayAADYARAJPANDEY1
Normal Cell Metabolism:
Cellular respiration describes the series of steps that cells use to break down sugar and other chemicals to get the energy we need to function.
Energy is stored in the bonds of glucose and when glucose is broken down, much of that energy is released.
Cell utilize energy in the form of ATP.
The first step of respiration is called glycolysis. In a series of steps, glycolysis breaks glucose into two smaller molecules - a chemical called pyruvate. A small amount of ATP is formed during this process.
Most healthy cells continue the breakdown in a second process, called the Kreb's cycle. The Kreb's cycle allows cells to “burn” the pyruvates made in glycolysis to get more ATP.
The last step in the breakdown of glucose is called oxidative phosphorylation (Ox-Phos).
It takes place in specialized cell structures called mitochondria. This process produces a large amount of ATP. Importantly, cells need oxygen to complete oxidative phosphorylation.
If a cell completes only glycolysis, only 2 molecules of ATP are made per glucose. However, if the cell completes the entire respiration process (glycolysis - Kreb's - oxidative phosphorylation), about 36 molecules of ATP are created, giving it much more energy to use.
IN CANCER CELL:
Unlike healthy cells that "burn" the entire molecule of sugar to capture a large amount of energy as ATP, cancer cells are wasteful.
Cancer cells only partially break down sugar molecules. They overuse the first step of respiration, glycolysis. They frequently do not complete the second step, oxidative phosphorylation.
This results in only 2 molecules of ATP per each glucose molecule instead of the 36 or so ATPs healthy cells gain. As a result, cancer cells need to use a lot more sugar molecules to get enough energy to survive.
Unlike healthy cells that "burn" the entire molecule of sugar to capture a large amount of energy as ATP, cancer cells are wasteful.
Cancer cells only partially break down sugar molecules. They overuse the first step of respiration, glycolysis. They frequently do not complete the second step, oxidative phosphorylation.
This results in only 2 molecules of ATP per each glucose molecule instead of the 36 or so ATPs healthy cells gain. As a result, cancer cells need to use a lot more sugar molecules to get enough energy to survive.
introduction to WARBERG PHENOMENA:
WARBURG EFFECT Usually, cancer cells are highly glycolytic (glucose addiction) and take up more glucose than do normal cells from outside.
Otto Heinrich Warburg (; 8 October 1883 – 1 August 1970) In 1931 was awarded the Nobel Prize in Physiology for his "discovery of the nature and mode of action of the respiratory enzyme.
WARNBURG EFFECT : cancer cells under aerobic (well-oxygenated) conditions to metabolize glucose to lactate (aerobic glycolysis) is known as the Warburg effect. Warburg made the observation that tumor slices consume glucose and secrete lactate at a higher rate than normal tissues.
2. Description
Autolab combined with the
software package is a computer-
controlled electrochemical
measurement system. It consists of
a data-acquisition system and a
potentiostat/galvanostat. It includes
a high-speed current integrator. It
is especially suitable for
electroanalytical applications.
Presented to CHEM 202 Class under
DR. NONITA P. PETEROS
8/9/2014
3. Presented to CHEM 202 Class under
DR. NONITA P. PETEROS
Computer monitor
Computer
Printer
Uninterrupted Power
Supply (UPS)
Autolab body
(with cell cables)
Wire connectors
8/9/2014
Computer Keyboard
6. Basic principle of a
potentiostat/galvanostat (PGSTAT)
Presented to CHEM 202 Class under
DR. NONITA P. PETEROS
8/9/2014
7. In potentiostatic mode, a
potentiostat/galvanostat (PGSTAT) will
accurately control the potential of the
Counter Electrode (CE) against the
Working Electrode (WE) so that the
potential difference between the working
electrode (WE) and the Reference
Electrode (RE) is well defined, and
correspond to the value specified by the
user.
Presented to CHEM 202 Class
under DR. NONITA P. PETEROS
8/9/2014
8. In galvanostatic mode, the current flow
between the WE and the CE is controlled.
The potential difference between the RE
and WE and the current flowing between
the CE and WE are continuously
monitored. By using a PGSTAT, the value
specified by the user (i.e. applied potential
or current) is accurately controlled,
anytime during the measurement by using
a negative feedback mechanism.
Presented to CHEM 202 Class
under DR. NONITA P. PETEROS
8/9/2014
9. Presented to CHEM 202 Class
under DR. NONITA P. PETEROS
the CE is connected to the output of an
electronic block which is called Control
Amplifier (CA)
control amplifier forces current to flow
through the cell. The value of the
current is measured using a Current
Follower (LowCF) or a Shunt (HighCR),
for low and high currents, respectively
potential
difference is
measured
always
between the
RE and S
with a
Differential
Amplifier
(Diffamp)
Depending on the mode the instrument is used
(potentiostatic or galvanostatic) the PSTAT/GSTAT
switch is set accordingly
signal is then fed into the
Summation Point (Σ) which,
together with the waveform
set by the digital-to-analog
converter (Ein) will be used
as an input for the control
amplifier
8/9/2014
10. The cell cables of the Autolab PGSTAT
(figure 2) have a total of five connectors:
WE, CE, RE, S and ground. The potential
is always measured between the RE
(blue) and the S (red) and the current is
always measured between the WE (red)
and CE (black). The ground connector
(green) can be used to connect external
devices to the same ground of the
PGSTAT.
Presented to CHEM 202 Class under
DR. NONITA P. PETEROS
8/9/2014
12. counter electrode (also known
as auxiliary electrode)
is used to close the current circuit in the
electrochemical cell. It is usually made of
an inert material (e.g. Pt, Au, graphite,
glassy carbon) and usually it does not
participate in the electrochemical reaction.
Presented to CHEM 202 Class under
DR. NONITA P. PETEROS
8/9/2014
13. Because the current is flowing between
the WE and the CE, the total surface area
of the CE (source/sink of electrons) must
be higher than the area of the WE so that
it will not be a limiting factor in the kinetics
of the electrochemical process under
investigation.
Presented to CHEM 202 Class under
DR. NONITA P. PETEROS
8/9/2014
14. reference electrode
an electrode which has a stable and well-
known electrode potential and it is used as
a point of reference in the electrochemical
cell for the potential control and
measurement.
The high stability of the reference
electrode potential is usually reached by
employing a redox system with constant
(buffered or saturated) concentrations of
each participants of the redox reaction.
Presented to CHEM 202 Class under
DR. NONITA P. PETEROS
8/9/2014
15. Moreover, the current flow through the
reference electrode is kept close to zero
(ideally, zero) which is achieved by using
the CE to close the current circuit in the
cell together with a very high input
impedance on the electrometer (> 100
GOhm).
Presented to CHEM 202 Class under
DR. NONITA P. PETEROS
8/9/2014
17. working electrode
the electrode in an electrochemical
system on which the reaction of interest is
occurring. Common working electrodes
can be made of inert materials such as
Au, Ag, Pt, glassy carbon (GC) and Hg
drop and film electrodes etc.
Presented to CHEM 202 Class under
DR. NONITA P. PETEROS
8/9/2014
18. For corrosion applications, the material of
the working electrode is the material under
investigation (which is actually corroding).
The size and shape of the working
electrode also varies and it depends on
the application.
Presented to CHEM 202 Class under
DR. NONITA P. PETEROS
8/9/2014
20. Two electrode setup
In a two-electrode cell setup (see Figure
4), CE and RE are shorted on one of the
electrodes while the WE and S are
shorted on the opposite electrode. The
potential across the complete cell is
measured. This includes contributions
from the CE/electrolyte interface and the
electrolyte itself.
Presented to CHEM 202 Class under
DR. NONITA P. PETEROS
8/9/2014
22. The two-electrode configuration can
therefore be used whenever precise
control of the interfacial potential across
the WE electrochemical interface is not
critical and the behavior of the whole cell
is under investigation. This setup is
typically used with energy storage or
conversion devices like batteries, fuel
cells, photovoltaic panels etc…
Presented to CHEM 202 Class
under DR. NONITA P. PETEROS
8/9/2014
23. It is also used in measurements of
ultrafast dynamics of electrode processes
or electrochemical impedance
measurements at high frequencies (> 100
kHz).
Presented to CHEM 202 Class
under DR. NONITA P. PETEROS
8/9/2014
24. Three electrode setup
The three-electrode cell setup is the most
common electrochemical cell setup used
in electrochemistry (see Figure 5). In this
case, the current flows between the CE
and the WE. The potential difference is
controlled between the WE and the CE
and measured between the RE (kept at
close proximity of the WE) and S.
Presented to CHEM 202 Class under
DR. NONITA P. PETEROS
8/9/2014
25. Because the WE is connected with S and
WE is kept at pseudo-ground (fixed, stable
potential), by controlling the polarization of
the CE, the potential difference between
RE and WE is controlled all the time.
The potential between the WE and CE
usually is not measured. This is the
voltage applied by the control amplifier
and it is limited by the compliance voltage
of the instrument.
Presented to CHEM 202 Class under
DR. NONITA P. PETEROS
8/9/2014
26. It is adjusted so that the potential
difference between the WE and RE will be
equal to the potential difference specified
by the user. This configuration allows the
potential across the electrochemical
interface at the WE to be controlled with
respect to the RE.
Presented to CHEM 202 Class under
DR. NONITA P. PETEROS
8/9/2014
28. To decrease the ohmic losses due to the
existence of residual solution between the
RE and WE (called the Uncompensated
resistance), a so-called Luggin-Haber (or
just Luggin) capillary can be used to bring
the RE extremity as close as possible to
the surface of the WE (see Figure 5).
Presented to CHEM 202 Class
under DR. NONITA P. PETEROS
8/9/2014
29. Since almost no current flows into the
reference electrode (typically, the leakage
current is a few pA at most), there is little
or no voltage drop across the capillary,
ensuring that the extremity of the capillary
is at a potential very close to the potential
of the RE.
Presented to CHEM 202 Class
under DR. NONITA P. PETEROS
8/9/2014
30. Four electrode setup
The four-electrode cell setup (see Figure
6) is used for applications where the
potential difference (between RE and S)
which occurs as a result of a passage of a
current across a well defined interface
(between WE and CE) needs to be
measured.
Presented to CHEM 202 Class under
DR. NONITA P. PETEROS
8/9/2014
31. This type of experimental setup is not
very common in electrochemistry and
usually it is used for measurements of
junction potentials between two non
miscible phases or across a membrane,
giving the possibility to calculate the
resistance of the interface or the
membrane conductivity.
Presented to CHEM 202 Class under
DR. NONITA P. PETEROS
8/9/2014
33. Operation
1. Turn on the computer and the screen.
2. If you want to measure: choose option
“1. Autolab applications”. If you want to load
or print files: choose option “2. User
configuration” (then go directly to step 5).
3. Turn on the potentiostat (“power ON”
on the potentiostat).
Presented to CHEM 202 Class under
DR. NONITA P. PETEROS
8/9/2014
34. 4. Turn on the cell (“cell ON” on the
potentiostat).
5. Double-click “administrador de
programas”, then “Autolab applications” and
finally “GPES” (in case you come from step
2, a message will appear and you have to
click on “ignorar”). The GPES software
consists of three windows (“edit procedure”,
“manual control” and “data presentation”)
and two bars (“GPES manager” and
“status”).
Presented to CHEM 202 Class
under DR. NONITA P. PETEROS
8/9/2014
35. In case you want to use the BIPOT
mode, click “BIPOT” instead of GPES”. The
BIPOT software is similar to the GPES
software.
6. Choose the electrochemical method on
the main GPES manager bar (“method”).
Example 1: to do a cyclic voltammogram
(CV), select “cyclic voltammetry (staircase)”
and then select “normal”. Example 2: to do a
chronoamperometry measurement, select
“chrono method (interval time >0.1s)” and
then select “amperometry”.
Presented to CHEM 202 Class
under DR. NONITA P. PETEROS
8/9/2014
36. 7. Connect the four connectors of the cell
cable (connected to the Autolab by means
of the DIN connector) to your system, taking
into account that the red connector is the
working electrode, the blue connector is the
reference electrode, the black connector is
the auxiliary or counter electrode, and the
green connector is the analog ground.
Presented to CHEM 202 Class
under DR. NONITA P. PETEROS
8/9/2014
37. In case you want to use the BIPOT
mode, connect the second working
electrode to your system.
Presented to CHEM 202 Class
under DR. NONITA P. PETEROS
8/9/2014
38. 8. Select ”utilities” and “check cell” to
check the connections and the noise level.
Press “measure” and if it says OK, go to
step 9. If not, go to “manual control” and
choose the appropriate “current range” until
the “measure” indicates OK.
Presented to CHEM 202 Class
under DR. NONITA P. PETEROS
8/9/2014
39. 9. Go to “edit procedure” to specify the
experimental parameters. For most
techniques, this window will consist of two
pages. Example 1: if you want to do two
cyclic voltammograms between 0 and
600mV at 100mV/s, go to page 1, complete
the “pretreatment” (if you need it; for the
example you do not need it)) writing the first
conditioning potential, the duration and the
equilibration time. Then complete the
“measurement” writing the number of scans
(2 for the example).
Presented to CHEM 202 Class
under DR. NONITA P. PETEROS
8/9/2014
40. Complete the “potentials”, specifying the
start potential (0V for the example), first
vertex potential (0.6V for the example),
second vertex potential (0V for the
example), step potential (0.001V is
reasonable), and scan rate (0.1V/s for the
example). Be careful with the units! Example
2:
Presented to CHEM 202 Class
under DR. NONITA P. PETEROS
8/9/2014
41. if you want to do a
chronoamperometric measurement at
300mV for 5min, go to page 1, complete the
“pretreatment” (if you need it; for the
example you do not need it) writing the first
conditioning potential, the duration and the
equilibration time.
Presented to CHEM 202 Class
under DR. NONITA P. PETEROS
8/9/2014
42. Then complete the “measurement” writing
the interval time (0.1s is reasonable) and the
number of potential steps (1 for the
example). Then complete the “potentials”
table (1 level for the example, as one 1
potential is applied) specifying the potential
(0.3V for the example) and the duration
(300s for the example). Be careful with the
units!
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8/9/2014
43. 10. Press start (you can abort the
measurement, clicking on “abort”).
11. Go to “data presentation” to see the
graphical display of the measured data and
to do modification and/or data analysis.
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8/9/2014
44. 12. Save you data selecting “file” and
“save data or scan” (depending on the
method you have used). Save the file in
your folder inside the “usuaris” folder.
13. Exit the program.
14. Turn off the cell.
15. Turn off the potentiostat.
16. Turn off the computer.
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8/9/2014
45. The Autolab control window
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8/9/2014
50. Samples
State
Species of interest must be dissolved in an
appropriate liquid solvent and capable of being
reduced or oxidized within the potential range
of the technique and electrode material.
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8/9/2014
51. Amount
The amounts needed to obtain
appropriate concentrations vary greatly
with the technique. For example, cyclic
voltammetry generally requires analyte
concentrations of 10–3 to 10–5 M,
whereas anodic stripping voltammetry of
metal ions gives good results with
concentrations as low as 10–12M.
Volumes may also vary from about 20 mL
to less than a microliter (with special
microelectrode cells).
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8/9/2014
52. Preparation
The degree of preparation required
depends on both the sample and the
technique. For determination of Pb(II) and
Cd(II) in seawater with a microelectrode
and square-wave anodic stripping
voltammetry (ASV), no preparation is
required.
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8/9/2014
53. In contrast, determination of
epinepherine in blood plasma at a glassy
carbon electrode with differential pulse
voltammetry (DPV) requires that the sample
first be pretreated with several reagents,
buffered, and separated.
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8/9/2014
54. Analysis Time
Once the sample has been prepared, the
time required to obtain a voltammogram
varies from a few seconds using single-
sweep square-wave voltammetry, to a
couple of minutes for a cyclic
voltammogram, to possibly 30 min (or
more) for a very-low-concentration ASV
determination.
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8/9/2014
55. Substance must be oxidizable or reducible in
the range were the solvent and electrode are
electrochemically inert.
Provides very little or no information on
species identity.
Sample must be dissolved.
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Limitations
8/9/2014
57. Cyclic Voltammetry (CV) is an
electrochemical technique which
measures the current that develops in an
electrochemical cell under conditions
where voltage is in excess of that
predicted by the Nernst equation. CV is
performed by cycling the potential of a
working electrode, and measuring the
resulting current.
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8/9/2014
58. • Cyclic voltammetry (CV) has become an
important and widely used
electroanalytical technique in many areas
of chemistry. It is rarely used for
quantitative determinations, but it is widely
used for the study of redox processes, for
understanding reaction intermediates, and
for obtaining stability of reaction products.
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8/9/2014
59. Cyclic Voltammetry can be used to study
qualitative information about
electrochemical processes under various
conditions, such as the presence of
intermediates in oxidation-reduction
reactions, the reversibility of a reaction.
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8/9/2014
60. CV can also be used to determine the
electron stoichiometry of a system, the
diffusion coefficient of an analyte, and the
formal reduction potential, which can be
used as an identification tool. In addition,
because concentration is proportional to
current in a reversible, Nernstian system,
concentration of an unknown solution can
be determined by generating a calibration
curve of current vs. concentration.
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8/9/2014
61. Conducting Polyaniline
Nanowire and Its Applications in
Chemiresistive Sensing
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8/9/2014
62. Linear sweep voltammetry is a
voltammetric method where the current at
a working electrode is measured while the
potential between the working electrode
and a reference electrode is swept linearly
in time. Oxidation or reduction of species
is registered as a peak or trough in the
current signal at the potential at which the
species begins to be oxidized or reduced.
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8/9/2014
63. While cyclic voltammetry is applicable to
most cases where linear sweep
voltammetry is used, there are some
instances where linear sweep voltammetry
is more useful.
In cases where the reaction is irreversible
cyclic voltammetry will not give any
additional data that linear sweep
voltammetry would give. In one example,
linear voltammetry was used to examine
direct methane production via a biocathode.
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8/9/2014
64. Since the production of methane from
CO2 is an irreversible reaction, cyclic
voltammetry did not present any distinct
advantage over linear sweep voltammetry.
This group found that the biocathode
produced higher current densities than a
plain carbon cathode and that methane
can be produced from a direct electrical
current without the need of hydrogen gas.
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8/9/2014
66. Chrono methods
The term Chrono methods includes all the
measurements of electrochemical signals
during a well-defined sequence of steps.
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8/9/2014
67. Impedance spectroscopy (IS) is a
general term that subsumes the small-
signal measurement of the linear electrical
response of a material of interest
(including electrode effects) and the
subsequent analysis of the response to
yield useful information about the
physicochemical properties of the system.
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8/9/2014
68. Analysis is generally carried out in the
frequency domain, although
measurements are sometimes made in
the time domain and then Fourier
transformed to the frequency domain.
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8/9/2014
69. It is currently broadly employed in various
scientific fields like biomolecular
interaction, fuel cell testing and
microstructural definition. Oftentimes, this
technique reveals information regarding
the electrochemical process reaction
mechanism.
This describes the fact that various
reaction stages will govern at definite
frequencies and such response reflected
by EIS helps determine the limiting step
rate.
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8/9/2014
70. Integrated Solid/Nanoporous Copper/Oxide
Hybrid Bulk Electrodes for High-
performance Lithium-Ion Batteries
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EIS spectra for the cell with
S/NP Cu/MnO2 electrode
before and after the rate
performance test.
8/9/2014