Glassy Carbon Electrode

 

glassy carbon electrode

 

Glassy carbon is abbreviated as glassy carbon. It is a process of slowly heating polyacrylonitrile resin or phenolic resin to high temperature (up to 1800°C) in an inert atmosphere to form a glass-like amorphous carbon, which is suitable as an electronic conductor material for electrodes. It is also widely used in table tennis soleplates.

 

Glassy carbon electrode is short for glassy carbon electrode.

 

The advantages of glassy carbon electrode are good electrical conductivity, high chemical stability, low thermal expansion coefficient, hard texture, good air tightness, and a wide range of potential applications (from about -1 to 1V, relative to saturated calomel electrode), and can be manufactured In the shape of electrodes such as cylinders and discs, it can be used as a substrate to make mercury film glassy carbon electrodes and chemically modified electrodes. It is increasingly used in electrochemical experiments or electroanalytical chemistry.

 

 

 

Electrode characteristics:

 

The glassy carbon electrode is one of the widely used working electrodes. It is a good inert electrode with good electrical conductivity, high hardness, high smoothness, high hydrogen overpotential, wide polarization range, chemical stability, and can be used as an inert The electrode is directly used for anode dissolution, cathode and voltammetric determination of variable valence ions, and can also be used as a chemically modified electrode.

 

 

 

Electrode treatment and maintenance:

 

The glassy carbon surface must be mirrored and clean. Because the surface of glass charcoal is easily polluted by some organic metal compounds, which seriously affects the measurement (no peaks, miscellaneous peaks, and no recurrence), it must be cleaned before measurement. There are three main methods. Chemical method 1. Nitric acid soaking And scrub. 2. Take

 

Soak and scrub with ammonia water absolute ethanol or ethyl acetate 1:1. 3. It can also be scrubbed with alcohol and then soaked in 6NHCL or 4NHO3. Electrochemical treatment: that is, repeated polarization (reset-scan) (anode-cathode to cathode) in the voltage range of +0.8V- (-1.8V (0.5MKcLPH7 except O2I) voltage range (reset-scan) (anode-cathode to cathode) if there is serious pollution and pits, Scratches can be treated mechanically, MgO powder (above 200 mesh) is placed on a wet flannel, and a small amount of water is added for polishing.

 

Combine several methods according to the electrode situation. It is not advisable to soak the electrode in strong acid, strong alkali and organic solvent for a long time.

 

Because the glassy carbon electrode is an inert electrode, so when using the plating scanning material is the scanning electrode, such as mercury plating, copper, gold is mercury film, copper film, gold film electrode. For example: anodic stripping mercury plating and gold plating. There are two types of mercury plating on glassy carbon: the first is the on-site mercury plating, that is, adding a certain amount of Hg+ (usually mercury oxide and mercury nitrate) to the sample to be analyzed for electrolytic enrichment At the point of the ion, an amalgam is formed at the same time. After scanning and dissolution, the ion or mercury film to be measured is completely dissolved under a positive potential. You can also take out the electrode and wipe the mercury film with filter paper. Ensure that the electrode surface is still in the original state during the second analysis to ensure reproducibility. Generally, the concentration of mercury ions is 500-1000 times the concentration of the measured ions. The second type is the pre-mercury coating, 1. Measure the long-term electrowinning of mercury under the ion electrolysis potential. For example, the mercury film can be produced by electrowinning at -0.2V for a long time when measuring cu, while preventing the danger of electrowinning cu, pb, cd, zn, this method is inefficient and takes a long time. 2. Under the condition of on-site mercury plating, after electrowinning for a period of time, scan dissolution, dissolve again at the termination potential for normal time, dissolve the ion to be measured, and then enrich-dissolve, repeat several times to get a layer without Mercury membrane for ion measurement.

 

For example, 0.5MKCL+2×10-2MHg+ dozens of drops of saturated NaSO3, stir at -1.4V for 5-10 minutes to enrich, scan to -0.1V in 15 seconds under stirring, and continue to stir and dissolve at -0.1V for 30 seconds , And then stir and enrich for 5-10 minutes in the reset state, stir and scan for 15 seconds to -0.1V, and then stir and dissolve at -0.1V for 30 seconds. After the solution is still, take out the electrode and rinse the electrode rod with water to prevent the coating from breaking. When plating mercury, pay attention to the fact that there should be no bubbles under the electrode, otherwise the mercury plating layer will be uneven and the electroplating will not be on. The electrode can be soaked in 1:1 nitric acid if it is not used in the short-term, and then washed and plated when it is used. save. The basic essentials of glassy carbon gold plating are the same as those of mercury plating.