Quasi-reference electrode glass

The electrochemical reduction of CO in fhe COj-methanol solution was carried out under high COj pressure. The high pressure apparatus was assembled from a SUS-316 sfainless steel tube. A glass inner tube was used to avoid contact of the electrolyte with the metal apparatus. Various metal electrodes were used in this study. The details have been described previously [9]. A Ft counter electrode and a silver quasi-reference electrode were used. Reagent grade methanol was used as the solvent. Tetrabutyl or tetraethyl ammonium salts were used as supporting electrolytes. 

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). 

Glass electrochemical cell. A microscope FTO-glass was chemically etched7 to produce a standard three-electrodes cell. Quasi-reference electrode was prepared by flash galvanic deposition directly on the FTO electrode. Electrochemical activity was monitored by cyclic voltammetry using a Fc-MeOH 10 4 mol/L solution in PBS 0.1 mol/L (pH 7.5). Electrodes shapes and distances have been optimized to obtain the configuration shown in Fig. 1, which produced experimental curves compatible with the E1/2 expected for first oxidation (+0.2-0.3 V vs. Ag). 

Cyclic voltammetry was performed in a jacketed glass container with an inner volume of 20 mL. The cell was fitted with a Teflon lid through which holes had been drilled to accommodate the electrodes (BAS 2013 MF working, Pt wire counter, and Ag wire quasi-reference electrode) and a nitrogen or argon gas bubbler. No internal standard was used to give an absolute reference for the Em potentials (i.e. NHE) and so all values are versus AgRE. 

A large variety of quasi-reference electrodes have been used based on metal wires such as silver [40], platinum [41], aluminium [42], tungsten [43], magnesium [44], etc. Typically electrodes are placed directly into the IL solution or separated from the main solution inside a fritted glass tube/compart-ment. In order to minimise liquid junction potentials in the latter case, the same ionic liquids as per the measurements is used as electrolyte. It is the authors experience that separation of the quasi-reference electrode allows for a reduction in potential drift when compared to direct insertion into the electrochemical cell. 

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... 

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