The Double-Pulse Galvanostatic Method

Since the charge is injected in a very short time (< 1 Jts), measurement often can be completed before diffusion limitation hn ij become significant. In this respect the charge-injection (coulostatfc) ii method is similar to the double-pulse galvanostatic method, except lh< f one has more freedom in the choice of the parameters of the pulse, sinot there is no need to match it to the second pulse. 

Fig. 6K Graphical representation of the double-pulse galvanostatic method, (a) the pulse shape (h) the response, calculated for, x /T = 100. A single pulse galvanostatic tran.sient,...

Fig. 75. The dependence of current on time of the double pulse galvanostatic method.

Galvanostatic Transient Technique. In the galvanostatic method a constant-current pulse is applied to the cell at equilibrium state and the resulting variation of the potential with time is recorded. The total galvanostatic current ig is accounted for (1) by the double-layer charging, /ji, and (2) by the electrode reaction (charge transfer), i. ... 

The intercept of the plot allows the determination of l/t o only when this term is appreciable compared to RT/F)ACdN (8). To overcome this limitation for fast electron-transfer reactions, where /q is large, the galvanostatic double-pulse method has been proposed (Section 8.6). 

Figure 8.6.1 Excitation waveform for the galvanostatic double pulse method.

Figure 8.6.2 Block diagram for galvanostatic double-pulse method. A two-electrode cell (i.e., with a common counter/reference electrode) is placed in a bridge circuit for compensation of the cell ohmic resistance, The bridge is adjusted with = Rb so that the...

Saji T, Yamada T, Aoyagui S (1975) Electron-transfer rate constants for redox systems of Fe(III)/Fe(II) complexes with 2,2 -bipyridine and/or cyanide ion as measured by the galvanostatic double pulse method. J Electroanal Chem Interfacial Electrochem 61 147-153... 

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