Platinum electrode arrangement

The Kellner electrolyzer with platinum electrodes arranged horizontally is one of the most efficient cells. The electrolytic vessel has a cascade-like bottom which... 

During measurement, the conductivity cell is filled with an electrolyte solution this cell is usually made of glass with sealed platinum electrodes. Various shapes are used, depending on the purpose that it is to serve. Figure 2.9 depicts examples of suitable cell arrangements. The electrodes are covered with platinum black, to avoid electrode polarization. The electrodes are placed close to one another in poorly conductive solutions and further apart in more conductive solutions. 

Figure 10. Electrode arrangement during the electrochemical treatment (ECT) with low-level direct current one platinum electrode is placed at the center of the tumor, four electrodes with opposite polarity are inserted at the border between the tumor and the surrounding liver tissue. Taken from Turler and coworkers. l...

Multiple column switching has been made possible by the construction of a cyclic CE microstructure in which four channels that are 20 mm in length are arranged to form a square, as illustrated in Figure 8.20.62 Two channels at each corner connect the loop to external reservoirs filled with separation buffer. Platinum electrodes are inserted into the reservoirs for the application of high voltages. One side of the device has a volume-defined injection scheme incorporated into it. The overall technique is called synchronized cyclic capillary electrophoresis.63... 

The conductivity cell is modified from a conventional type. It is made of borosilicate glass, which resists the attack of anhydrous chlorine and bromine trifluorides, and is equipped with two smooth platinum electrodes to minimize electrode corrosive effects. These electrodes are approximately 12x25 mm. in size, held 1.5 mm. apart with borosilicate glass spacers. The arrangement of electrodes and leads is shown in Figure 1. An internal thermocouple well leads from the top of the cell to a point near the electrodes and contains a copper constantan thermocouple. The cell constant is determined by measuring the cell resistance... 

An apparatus similar to that used in the popular disc electrophoretic technique can be used for isoelectric focusing. One modification concerns the insertion of the tubes in a jacket through which water of 2°C can circulate only the tips of the tubes will be in contact with the electrolytes. Platinum electrodes should be used and arranged at the extremities of the tubes. The anolyte and catholyte are 0.02 Jlf phosphoric acid (pH 2.2) and 0.01 M sodium hydroxide (pH 12.0). Excess persulfate should be eliminated by maintaining a current of 1 mA per tube for 10 minutes. 

An ordered arrangement of GOD and ferrocene on a platinum electrode has been obtained by using the Langmuir-Blodgett (LB) technique (Moriizumi et al., 1988). Monomolecular films on electrodes were made by mixing the mediator with lipid followed by adsorption of GOD on the film at the trough surface. The quantity of GOD could be flexibly controlled by the number of LB films, thus giving sensors of different sensitivity. 

To apply to specific examples the principles just discussed let us consider what happens at each of the electrodes when a current consisting of four electrons passes in turn through (a) a cell consisting of silver electrodes in a silver nitrate solution, (h) copper electrodes in a copper sulphate solution, (c) platinum electrodes in a solution containing a mixture o ferrous and ferric chlorides, and (cl) platinum electrodes in an acidified water solution. The arrangement is shown diagrammatically in Fig. 2. When the elect reus moving in the reverse direction to the... 

C, has been described by Wendiandt (112). The sample holder and furnace arrangement are shown in Figure 11.28. The sample A, in the form of a pressed disk (1x5 mm) was placed between two platinum electrodes (7.0 mm in diameter). Leads to the electrodes were led out of the furnace area by one-holed ceramic insulator tubes. To maintain a constant tension on the sample disk by the electrodes, one electrode is spring-loaded at H. The furnace consists of a Nichrome resistance wire heater element on a Vycor tube suitably insulated with a ceramic material- A clamp G secures the tube furnace to the base. Furnace temperature, Tf, is detected by a Chromel-Alumel thermocouple located at D. The other components of the EC apparatus are the same as those previously described. The apparatus was used oil pure... 

The arrangement is such that only radicals formed in the vicinity of the platinum electrode are observed, but this may be either the anode or cathode of the cell depending on the direction of the applied potential The usual sample tube used for the ESR experiments is basically very similar to that shown in Fig. 24 but without the electrodes. The same... 

The measurements were conducted by applying the cell in oxidic melts containing small and equal molar concentrations of antimonyflll) and antimonyfV) (or arsenic(lll) and arsenic(V)) oxide. The special arrangement used separated the melt essentially from the surrounding atmosphere and allowed electrochemical pumping of oxygen into, and out of, the melt by means of a platinum electrode and a zirconia electrode or the zirconia crucible, which contained the melt and served as the oxide ion-conducting wall [28]. The concentration ratio of the polyvalent ionic species could thus be well adjusted. 

Experimental arrangement for studying a heterogeneous reaction between zirconium silicate (ZS) refractory (1) and oxidic melt (2). The zirconia electrode (3) is used as a reference electrode for the platinum electrode (4) measuring the oxygen fugacity of the melt, for the ZS crucible (1), and for a short-circuit with ZS, via platinum contact (3). 

LB chlorophyll monolayers (25 mN/m 1.4 nm2/molecule) on Pt electrodes showed low photoactivity, possibly caused by a quenching of excited states by the metal electrode or by total reversibility of electron exchange. Addition of electron acceptors, e.g., quinones, had no effect. The optically transparent tin oxide semiconductor electrode proves to be a much better subphase for the generation of photocurrents. Chlorophyll-coated Sn02 combined with a platinum electrode gave approximately 100 nA/cm. Similar results were obtained with photovoltaic systems of the form mercury droplet/buffer solution/chlorophyll a monolayer/electron acceptor monolayer/aluminum (Fig. 6.9.3). The quantum yield of such monolayer arrangements never exceeded 10" in any of these systems and is thus far away from competitive inorganic semiconductor cells (Norris and Meisel, 1989). 

Figure 9 shows the effects of different experimental arrangements on the distribution curves of 2.5 X 10" M KF. In one instance, the perforated platinum electrode was replaced by a snugly fitting Teflon disk, located about 3 cm. from the interface, provided with only two small holes (Vs inch in diameter) to allow fluid transfer. The apparent distribution coeflBcient is about four times that found for unhindered diffusion. Hydrogen ion transfer is appreciably less. Constitutional supercooling see below and Ref. 146) in the interface region may perhaps have contributed to this rise of the distribution coeflBcient. Qualitatively similar results were found for HF. 

The reference electrodes employed were either a SCE or a Ag/3M NaCI (aq) electrode. The reference electrode was usually separated from the bulk electrolyte by a sintered glass-irit arrangement The films were deposited on either gold-plated stainless steel or platinum electrodes and growth was terminated when a fixed charge had been passed. The films were then peeled from the electrode, rinsed thoroughly and dried All films were dried prior to elemental analysis at 120°C in dynamic vacuum for 24 hours. 

These coated glasses can be used as working electrodes [optically transparent electrodes (OTE)] in standard three-electrode arrangements provided that both glass and coating are chemically and electrochemically stable and inert in the used electrolyte solution and the applied range of electrode potentials. The use of a modified infrared spectroscopy transmission cell equipped with quartz windows for UV-Vis spectroelectrochemistry has been described [18]. Platinum layers deposited onto the quartz served as an optically transparent working electrode and an additional platinum layer served as a pseudo-reference electrode. A counter electrode outside the thin layer zone (in one of the tubes used for solution supply) served as a counter... 

The use of an infrared microscope enables the investigation of the surface of rather small electrodes. The resulting miniaturization of the necessary electrochemical cell allows its operation as a fiow cell in thin layer arrangement [242]. Combined with a rapid-scan FTIR spectrometer, acquisition of infrared spectra during electrode potential scans at a rate of d /dr = 200 mV-s are possible. The time resolution is equivalent to one complete spectrum recorded every 2.6 mV. The formation of various reaction intermediates of methanol oxidation in alkaline solution at a platinum electrode could be assigned to specific electrode potential ranges. 

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