Pretreatment of glassy carbon electrodes by anodic galvanostatic pulses with a large amplitude

Abstract

Glassy carbon electrodes (GCEs) can be activated by the passage of large-amplitude (for example, 20-mA) anodic galvanostatic pulses with durations shorter than 1 second. The increased activity stems from an increase in the rate of charge-transfer reactions and from the adsorption accumulation of the analytes on the electrode surface, which is demonstrated for catecholamines and ascorbic acid. As demonstrated by X-ray photoelectron and fast-atom-bombardment mass spectrometry, the gakanostatic treatment leads to an increase in the amount o f chemisorbed oxygen. Scanning electron microscopy shows very small mechanical changes o f the electrode surface. The activation effect depends on the composition of the test solution and the character of the analytes. There is an optimal electric charge that produces the highest electrode activity and lowers the limits of determination for catecholamines by approximately two orders of magnitude; on further increase in the charge, the electrode activity decreases (due to the formation of a thick layer of graphite oxide). The activation effects are less pronounced in flow-through measurements. The method can be readily implemented for the periodic, automated reactivation of glassy carbon electrodes, but the optimal conditions must be found experimentally for various systems.

Reduction of Carbon Dioxide on Modified Glassy Carbon Electrodes

“…14 is associated with reduction of oxygenated species first formed on the GC electrode surface during the anodic activation period. Many papers in literature 21,[38][39][40][41] report the appearance of oxygenated species on GC electrodes after anodic activation, and despite the wave at Ϫ1.05 V in Fig. 14 could appear rather complex, there is no doubt that oxygenated species should be reduced at this potential.…”

“…Much attention has been paid in literature to pretreatment of solid electrodes, and chemical, thermal, radiative, and electrochemical treatments have been used to produce surfacial changes. Anodic, galvanostatic pulses were successfully used by Mattusch et al 21 to activate GC electrodes by increasing the amount of chemisorbed oxygen. Activation of GC electrodes has been also attributed to surface roughening, removal of contaminants, exposure of fresh carbon edges, and introduction of redox functionalities.…”

“…[6][7][8][9][10][11][12][13][14][15][16][17][18] Because of the low efficiencies obtained in the process, scientists are now modifying some experimental parameters to improve previous results. Chemical and electrochemical modifications of electrodes have been introduced leading to catalytic effects for reduction of CO 2 compared with those results obtained on metallic electrodes under the same conditions; [19][20][21] the nature of the electrolytic medium has also been treated in several studies. [22][23][24][25] High pressure electroreduction of CO 2 on several electrodes, including glassy carbon (GC), has been reported by Sakata et al, [26][27][28] obtaining a distribution of products that strongly depends upon current density.…”

Espectroelectroquímica UV-VIS con electrodos serigrafiados: estudio y determinación de neurotransmisores

“…Por otro lado, la necesidad de utilizar tintas de impresión que suelen contener algunos aglutinantes minerales o polímeros aislantes que mejoran la adherencia sobre el sustrato [99] hace que aumente la resistencia de los electrodos serigrafiados, lo que se traduce en unas cinéticas más lentas de las registradas por ejemplo en electrodos de carbono vítreo. Se han descrito procedimientos en los que se ha sometido a electrodos de carbono a un tratamiento previo con mejoras significativas en cuanto a los procesos de transferencia electrónica en los que se han utilizado posteriormente [100][101][102][103][104][105][106][107][108][109].…”