Understanding the influence of cold plasma treatment on the electroanalytical performance of carbon-based electrodes

Abstract

This work describes the use of a surface modification procedure to improve the electrochemical response of carbonaceous materials that are commonly used as working electrodes in electroanalysis. A 3D printed electrode (Carbon-Black PLA) was exposed to the cold plasma treatment using CO2 and O2, and it was possible to generate surface functional groups at the same time that a higher amount of the insulating material was removed, thus, making electrodes with lower resistance to the charge transfer and, consequently, better electrochemical responses. Also intended to verify if these changes provide a better sensor, the electrodes were used in electrochemical methods to detect Nitrite, a biomarker, and Dopamine, a neurotransmitter. It was possible to confirm that the cold plasma treatments proposed improve the CB/PLA electrodes electrochemical performance, even in real saliva samples. In another step of this work, Pyrolytic Graphite Sheet (PGS), which is vastly reported in literature as a base substrate for the construction of modified electrodes, but rarely used as a bare electrode, was exposed to the cold plasma treatment using CO2 and O2. It was demonstrated that this treatment generates higher surface area, roughness and functional groups concentration, alongside with lower resistance to the charge transfer and higher structural disorder without losing the material intrinsic characteristics of stacked graphene layers. Intended to verify if these changes also provide a better sensor, electroanalytical methods were developed to detect MDMA, a molecule with high forensic interest, and the antibiotics Chloramphenicol, Ciprofloxacin and Sulphanilamide. From the developed methods it was possible to confirm that both surface cold plasma treatments enhanced the performance of PGS electrodes. Also, it was possible to use the electrodes in real samples, such as saliva, seized samples and tap water.