Quasi-reference electrodes QRE

A quasi-reference electrode (QRE) is a general phrase for any poorly defined or unpoised RE. A QRE typically consists of an inert metal wire such as platinum or gold. A silver wire can also be used, so long as silver ions do not interfere with the measurements. The potential should ideally be steady, but the actual potential is not predictable if it is unpoised. Some methods to circumvent the ill-defined potential are to compare the potential to a conventional RE, or to include an electrochemical couple as an internal standard (see Section 4.6.2). A QRE is a low-impedance RE, but is also a polarizable electrode. 

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One solvent studied is DMSO on Pt(lll). As shown in Fig. 5.19, peaks associated with the symmetric (2900 cm ) and antisymmetric (3000 cm ) CH stretches exhibit considerable potential dependence. An analysis of these spectra indicates that at potentials near -i- 200 mV vs Ag (quasi reference electrode, QRE) the DMSO molecule must reorientate so that the preferred orientation of the CH-related dipoles is no longer normal to the electrode surface. 

The auxiliary and reference electrodes in electronic and other spectroelectrochemical experiments are similar to those used in conventional electrochemical cells. They must be small enough to fit into the cell without complicating its construction. Common auxiliary electrodes are small platinum wires, paddles, or coils. Reference electrodes (see Chapter 4) are frequently Ag/Ag+ or AgCl because these can be miniaturized. In non-quantitative appUcations, silver wire coated with AgCl or a simple silver wire as a pseudo reference (quasi-reference electrode, QRE) can be used. However, commercially available aqueous and non-aqueous Ag/Ag+ in which the electrode is separated from the analyte solution via a frit are preferable because they are more stable. The majority of electronic spectroelectrochemical experiments are conducted using OTEs in either thin layer (finite) or semi-infinite diffusion regimes. 

Ghilane et al. [35] have described solid-state quasi-reference electrodes (QRE) based on metal (Ft or stainless steel) coated with partially oxidized polypyrrole PPy. It was shown that such QRE can be used in both aqueous and aprotic media. As in the cases discussed above, characteristic of this approach is the absence of any liquid component in the electrode design. 

Bard AJ (2012) Quasi-reference electrodes (QRE). In Bard AJ, Inzelt G, Scholz F (eds) Electrochemical dictionary, 2nd edn. Springer, Berlin, p 776... 

After the wet separation process, the obtained M(TESA) amide salts were dissolved in [P2225] [TESA] on the electrodeposition process. In the case of the three electrode systems as shown in Eig. 6.29, Cu cylindrical cathode was used for the electrodeposition. A prismatic Nd-Ee-B rod was employed as an anode and surrounded by a soda lime tube with a Vycor glass filter at the bottom in order to prevent the diffusion of dissolution components from the anode into the electrolyte. Then, Pt wire was applied as a quasi-reference electrode (QRE), because the... 

The cell is constituted by two metallic holders both of them have a eentral hole through which the light beam passes, and two other small holes that are used to fill the cell with the solution. These two holders sandwieh two quartz windows and then they are screwed together. By means of suitable spacers it is possible to leave a thin cavity between the quartz windows that is filled with the solution. In this thin cavity a polyethylene spacer (ca. 150 pm thick) with melt-sealed eleetrodes is also contained. WE and CE are metallic minigrids and a Ag wire plays the role of quasi reference electrode (QRE), the potential of whieh ean be considered constant for a short time interval. 

Fig. 2.9 Demonstration of the microfabrication of EIS-QCM electrode chip that was made on a 10 MHz AT cut quartz crystal formed EIS. It has a 2.5 mm disk-working electrode on both sides of 10 MHz AT cut quartz. Ring-shaped counterelectrodes (CE) and quasi-reference electrodes (QRE) are patterned around the circular working electrodes on one side and narrow gaps between disk and ring electrodes to support EIS and QCM...

Fig. 2.6 Current-potential curves for (A) p-InP, (B) p-GaAs, and (C) p-Si electrodes in 0.3 M TBAP in methanol (40 atm C02) (b) in the dark and (a, c) under illumination. Curves a and c correspond to the behavior corrected and uncorrected for ohmic losses, respectively. Curve d was obtained for a metallic Cu electrode. (QRE stands for quasi-reference electrode).

The equipment and the experimental procedures using the C02-methanol medium have already been described in previous papers. . For the photoelectrochemical experiments, a stainless steel pressure vessel was equipped with a 2-cm thick quartz window for illumination, p-type InP and GaAs wafers were cut into ca. 0.4 cm x 0.5 cm electrodes and were mounted using epoxy resin. Ohmic contact was made with successive vapor deposition of Zn (30 mn) and Au (100 nm), which was annealed afterward at 425 C in Ar. A silver wire (0.8 mm dia) was used as a quasi-reference electrode (Ag-QRE, ca. +80 mV vs. SCE). A Pt wire (0.8 mm dia) was used as the counter electrode. The photocathode was etched in hot aqua regia for ca. 5 s before each experiment. The electrolyte solution [3 cm, 0.3 mol dm" tetrabutylammonium perchlorate (TBAP) in CH3OH] was placed in a glass cell liner in the stainless steel vessel. Gases were introduced into the pressure vessel and were left to equilibrate for one hour at the desired pressure (1 to 40 atm). 

QRE quasi -reference electrode (metal wire inserted in solution)... 

The use of quasi-reference (or pseudo-reference) electrodes, QRE, is a common practice in electrochemical studies in nonaqueous solvents, where, as is flie case with ionic liquid investigations, well-defined reference electrodes are difficult to... 

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