Thin-layer cell generator electrode

The detection limit for TLV has been improved substantially by using differential pulse and square-wave voltammetry (Chap. 5). For example, detection limits in the 10 8 M range and below have been demonstrated in thin-layer cells requiring less than 100 /xL of sample [61,62]. One practical application of twin-electrode thin-layer cells is in the automatic electrochromic rearview mirror for automobiles. A cell with optically transparent electrodes is placed in front of a mirrored surface. At night, electrolysis in the cell to generate colored material can rapidly reduce glare from following vehicles. 

Figure 4.15 Principal construction of a thin-layer cell for determination of adsorption isotherms of metal ions. WE working electrode, GE generator electrode, RE reference electrode (not reversible for the investigated metal ions), V thin-layer compartment, C channel to keep electrical contact between the thin-layer compartment and outer electrolyte, E potential between the working and reference electrodes, potential between the generator and reference electrodes (to be kept constant), and ig current through the generator electrode after a potential jump in the potential of the working electrode.

There are several modes of operation of the SECM. In the tip generation/substrate collection (TG/SC) mode, the tip is used to generate a reactant that is detected at a substrate electrode. For example, the reaction O+ne occurs at the tip and the reverse reaction occurs at the substrate. This mode of operation is similar to that at the rotating ring-disk electrode. Similar behavior is observed for a pair of side-by-side microband electrodes and in thin-layer cells. In the SECM,... 

Figure 12.1 Schematic of the spectroelectrochemistry apparatus at the University of Dlinois. The thin-layer spectroelectrochemical cell (TLE cell) has a 25 p.m thick spacer between the electrode and window to control the electrolyte layer thickness and allow for reproducible refilbng of the gap. The broadband infrared (BBIR) and narrowband visible (NBVIS) pulses used for BB-SFG spectroscopy are generated by a femtosecond laser (see Fig. 12.3). Voltammetric and spectrometric data are acquired simultaneously.

This system was subsequently investigated by Christensen et at. (1990) also using in situ FTIR, who observed identical product features (see Figure 3.48). In order first to compare directly the IR spectrum of oxalate generated in situ, the authors took advantage of the surface reactivity of Pt and the poor diffusion of species to and from the thin layer. Thus, a solution of oxalic acid in the electrolyte was placed in the spectroelectrochemical cell, the potential of the platinum working electrode stepped to successively lower values and spectra taken at each step. The spectra were all normalised to the reference spectrum collected at the base potential of 0 V vs. SCE. As a result of the deprotonation of adventitious water ... 

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