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Glassy carbon electrode
Glass carbon, referred to as glassy carbon, is a kind of amorphous carbon that is shaped like glass by slowly heating polyacrylonitrile resin or phenolic resin to a high temperature (up to 1800℃) in an inert atmosphere. It is suitable for the electronic conductor material of electrode and widely used in the bottom plate of table tennis ball.
Glassy carbon electrode is short for glass carbon electrode.
The advantages of glass carbon electrode are good conductivity, high chemical stability, small thermal expansion coefficient, hard texture, good air tightness, wide range of potential application (about -1 ~ 1V, relative to saturated calomel electrode), can be made into cylindrical, disc electrode shape, can also be made of mercury film glass carbon electrode and chemical modified electrode. It is widely used in electrochemical experiment and electroanalytical chemistry.
Characteristics of electrode:
Glassy carbon electrode is one of the widely used work electrode, it is a kind of good inert electrode, has the good electrical conductivity, high hardness, high degree of finish, high hydrogen overpotential, wide range of polarization, and chemical stability, can be used as an inert electrode directly used in anodic dissolution, cathode and intending voltammetric determination of ions, and can be chemically modified electrodes.
Electrode treatment and maintenance:
The glassy carbon surface must be mirror and clean. Because the surface of glassy carbon is easily polluted by some organic metal compounds, which seriously affects the measurement (no peak, no miscellaneous peak, no recurrence), it must be cleaned before measurement. There are three main methods, chemical method.1.Nitric acid soaking and scrubbing.2.with
Ammonia water anhydrous ethanol or ethyl acetate1:1Soak and scrub.3.Alcohol can also be used after scrubbing and then with6NHCLor4NHO3Soak. Electrochemical treatment: i.e.+0.8V-(-1.8V(0.5MKcLPH7exceptO2IRepeated Polarization (Reset) in Voltage Range-Scanning (Anode)-If the cathode is seriously polluted and pitted, scratches can be treated mechanically.MgOPowder(200Put it on wet velvet cloth and polish it with a little water. Also
Several methods are combined according to the condition of electrodes. It is not advisable to immerse the electrode in strong acid, alkali and organic solvents for a long time.
Because glassy carbon electrodes are inert electrodes, they are scanned electrodes using scanned materials, such as mercury, copper, gold, mercury, copper and gold film electrodes. For example, there are two kinds of mercury plating: anodic stripping and gold plating, glassy carbon mercury plating: the first is isotopic mercury plating, that is, adding a certain amount of mercury to the sample being analyzed.Hg+Mercury oxide and mercury nitrate are usually used to electrolytically enrich the sites to be ionized, and mercury amalgam is formed at the same time. After scanning and dissolution, the ions or mercury film to be measured can be completely dissolved at a positive potential. The mercury film can also be wiped off with filter paper. In order to ensure the reproducibility of the second analysis, the surface of the electrode is still in its original state. The concentration of mercury ion is generally the concentration of the measured ion.500-1000The second is to deposit mercury film.1.Mercury was electrodeposited for a long time at the positive ion electrolytic potential to be measured. As measuredcuAvailable in-0.2VPrevent electrowinning by electrowinning mercury film for a long timecu,pb,cd,znThe danger is that this method is inefficient and takes a long time.2.Under the condition of isotopic mercury plating, after electrowinning for a period of time, scanning dissolution, dissolution at the termination potential for a general time, dissolution of the ions to be measured, so enriched.-A layer of mercury film without ions to be measured can be obtained by dissolution several times.
as0.5MKCL+2-times; 10-2MHg+more than ten drops of saturated NaSO3 were enriched in-1.4V stirring for 5-10 minutes, scanned to-0.1V in 15 seconds under stirring condition, stirred to dissolve for 30 seconds under-0.1V, stirred to concentrate for 5-10 minutes under reset condition, stirred to scan to-0.1V in 15 seconds, stirred to dissolve for 30 seconds under-0.1V, stirred to dissolve at rest, removed the electrode rod and washed with water to prevent the coating from breaking. When plating mercury, it should be noted that there is no bubble under the electrode to absorb, otherwise the mercury coating is uneven and the electroplating can not be achieved. In the short term, the electrode can not be soaked in 1:1 nitric acid, and then washed and plated when used. In the long run, it should not be washed and dry preserved without mercury removal. The basic principle of glassy carbon gold plating is the same as mercury plating.