1 / 9

Chapter 25 Voltammetry 1 Voltammetric instrumentation

Chapter 25 Voltammetry 1 Voltammetric instrumentation. 1.1 Three electrodes voltammetry. Fig. 25-2 (p.718) A system for potentiostatic three-electrode linear-scan voltammetry. Fig. 25-8 (p.724) A three-electrode cell for hydrodynamic voltammetry. 1.2 Working electrodes.

Download Presentation

Chapter 25 Voltammetry 1 Voltammetric instrumentation

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Chapter 25 Voltammetry1 Voltammetric instrumentation 1.1 Three electrodes voltammetry Fig. 25-2 (p.718) A system for potentiostatic three-electrode linear-scan voltammetry Fig. 25-8 (p.724) A three-electrode cell for hydrodynamic voltammetry.

  2. 1.2 Working electrodes At +E limit, oxidation of water to generate O2: 2H2O  4H+ + O2(g) + 4e- At -E limit, reduction of water to generate H2: 2H2O + 2e-  H2 + 2OH- Fig. 25-4 (p.720) Potential ranges for three types of electrodes in various electrolyte solutions

  3. 1.3 Excitation signals Fig. 25-1 (p.717) Potential excitation signals used in voltammetry

  4. 1.4 Voltammograms (voltammetric waves): graphs of current vs applied voltage Fig. 25-6 (p.722) Linear-sweep voltammogram for the reduction of a hypothetical species A to give a product P.

  5. 2 Hydrodynamic Voltammetry (Stirred Solution) 2.1 Concentration profiles at electrode surfaces (stirred solution) Fig. 25-12 (p.726) Flow patterns and regions of interest near the working electrode in hydrodynamic voltammetry Fig. 25-13 (p.727) Concentration profile at an electrode-solution interface during the electrolysis A + ne- P from a stirred solution of A.

  6. 2.2 Application of hydrodynamic voltammetry - Single voltammogram can quantitatively record many species provided enough separation between waves (01.~0.2 is required) - Problems with dissolved O2 – must purge solutions Further reduction of H2O2 water Reduction of O2 to hydrogen peroxide Fig. 25-16 (p.729) Voltammogram for the reduction of oxygen in an air-saturated 0.1M-KCl solution Fig. 25-14 (p.729) Voltammograms for two-components mixtures, with E1/2 differ by 0.1 V

  7. 3 Cyclic Voltammetry (unstirred solution) On a single electrode apply both anodic and cathodic sweep. 3.1 Fundamental studies System is reversible if E = 0.0592/n and ipc = ipa Note: Epc = E0 -1.1RT/nF 3.2 Quantitative analysis (not common)

  8. Switching potential Fig. 25-23 (p.737) Cyclic voltammetric excitation signal

  9. 3.1 Fundamental studies System is reversible if: E = 0.0592/n and and ipc = ipa Note: Epc = E0 -1.1RT/nF 3.2 Quantitative analysis (not common) Fig. 25-24 (p.738) a) Potential vs. time waveform and b) cyclic voltaqmmogram for a solution that is 0.6mM k3Fe(CN)6 and 1.0 M in KNO3

More Related