C.v data
- 1. CYCLIC VOLTAMMETRY By: Halavath Ramesh Department of Chemistry Loyola College, Chennai UNIVERSITY OF MADRAS
- 2. Cyclic voltammetry • 1.cyclic voltammetry(cv) is an Eletrochemical technique which measures the current that develops in an electro chemical cell under conditions where voltage is in excess of that predicted by the nerst equation.cv is performed by cycling the potential of a working electrode and measuring the resulting current.
- 3. Main points • 1.A scar in the direction of more negative potential is teruned a forward scan and oppositie direction is called reverse scan. • 2.General cyclic time range 1ms or less to 100s or more. • 3.The potential of the working electrode is measured against a references electrode which maintain a constant potential and the resulting applied potential produces an excitation signal such as that of figure1.
- 4. Introduction • Cyclic voltammetry(cv) is an important and widely used electro analytical technique. • Although cv is infrequently used for quantitative analysis , it finds wide applicability in the study of oxidation/ reduction reaction. • A cv experiment may use one full cycle, a partial cycle or several cycles. • During the cv experiment ,the current response of a small stationary electrode in an unstirred solution is excited by a triangular potential wave form. • The triangular wave form produces the forward and then the reverse scan.
- 5. Switching potential • The potential is first varied linearly from +0.8v to -0.15v versus a saturated calomel electrode , at which point the scan direction is reversed and the potential is returned to its original value of +0.8v. • The potential at which reversal takes place ( in this case -0.15v and +o.8v) are called switching potentials.
- 6. 5 • 4.In the forward scan of figure1,the potential first scans negatively, starting from a greater potential(a) ending at a lower potential(d). • 5.The potential extrem(d) is call the switching potential.and is the point where the voltage is sufficient enough to have caused an oxidation or reduction of an analyte. • 6.The reverse scan occurs from(d) to (g).
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- 8. 7 • 7.where the potential scans positively figur1 shows a typical reduction occuring from (A) to(d) and an oxidation occuring from (d) to (g). • 8.A cyclic voltamgram is obtained by measuring the current at the working electrode during the potential scan.figur2 , shows a cyclic voltammogram resulting from a single electron reduction and oxidation.
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- 11. Examples • Another example experiment was performed on copper sulfate • using the CyclicVoltammetry test script. In this example, • cyclic voltammetry was used to plate copper on a graphite • working electrode and then strip it back again. This chemical • reaction was: • (reduction) Cu2+ + 2e– ––> Cu (metallic) • (oxidation) Cu ––> Cu2+ + 2e–
- 15. Triangular form On x-axis potential.y.time
- 17. Instrumentation 1.A cv system consists of an electrolysis cell,working electrode,counter electrode,reference electrode,and electrolytic solution.
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- 20. 1. CYCLIC VOLTAMMETRY HAS BECOME AN IMPORTANT AND WIDELY USED ELECTRO ANALYTICAL TECHNIQUES IN MANY AREAS OF CHEMISTRY. 10. Applications. *It is used for identical tools. *.It is also used in cellular biology.
- 21. RESEARCH AREA IS IN ELECTROCHEMISTRY MODIFIED THE ELECTRODES
- 22. References • 1.Instrumental methods of chemical analysis.(Analytical chemistry) • Author.DR.B.K.SHARMA • Skoog, D.; Holler, F.; Crouch, S. Principles of Instrumental Analysis 2007 • Kissinger, P. T., Heineman, W. R., “Cyclic Voltammetry,” Journal of Chemical Education, 60, 702 (1983).
- 24. “GOOD SCIENCE IS GOOD PLANNING”