Influence of the Solvent on the “Casting” Methodology for MWCNT‐Modified Glassy Carbon and Platinum Electrodes

Abstract

The choice of electrode material and surface preparation method are usually dictated by the suitability of the electrode to observe an electrochemical parameter, such as heterogeneous electron transfer rate, surface coverage, or redox potential. Thus, the glassy carbon (GC) and platinum (Pt) electrodes were modified with multiwalled carbon nanotubes (MWCNT) by direct “casting” modification using nine different aliquots of solvents. After drying at room temperature, the modified electrode showed distinct redox peaks corresponding to ferrocyanide oxidation/reduction. Using chemometrics, the cyclic voltammograms with higher current intensity were obtained for those in which ethanol, water and acetone as dispersing agents were used for GCE and dimethylformamide, water and acetone for Pt electrode modification.

Multi-walled carbon nanotube functionalization and the dispersing agents study applied for the glassy carbon electrode modification and voltammetric reduction of nitrofurazone

“…However, the use of commercial CNTs is limited due to Van der Waals interaction's existence that provides low dispersion in water and other solvents [5,17]. Consequently, this is one of the main problems encountered in commercial CNT handling applied in many fields, especially in electroanalysis [17][18][19][20]. In this sense, several investigations have focused on solving this problem, involving different approaches to improve the CNT handling with the introduction of groups or the molecule fixation on the CNT walls, which provide them with a hydrophilic character making them compatible with certain solvents [3,5,21].…”

“…The electrode surface modification by direct casting is the most widely used method for rapid and easy preparation of a chemically modified electrode (CME) [20,22,23]. The method consists of an aliquot deposition with CNT suspension microliters on solid electrode surface, the solvent being evaporated at room temperature.…”

“…Therefore, in the CME developing process, the CNT dispersion is a key factor. In addition, it is necessary to acquire a method that provides homogeneity of CNT films and, consequently, reproducibility of the resulting electrodes [3,5,20]. Literature indicates several solvents as dispersing agents, being hydrophilic or hydrophobic, such as water, ethanol, dimethylsulfoxide, acetonitrile, chloroform, tetrahydrofuran, toluene, 1,3-dioxolane, 1,2-dichlorobenzene, 1-methylnaphthalene, and N,N-dimethylformamide (DMF) [17][18][19][20][21].…”

Molybdenum sulfide for energy applications

“…It probes into the porosity effect and kinetics of the electrochemical reactions. [171][172][173][174][175][176][177][178] Such studies, were however limited to mainly carbon materials (such as carbon nanotubes or graphene) for specific redox couple (such as ferro/ferricyanide) but not its effect on electrocatalysis of HER. 171-172, 174-175, 178 These studies gave significant insights into the role of solvents and caution the readers that certain enhanced properties are sometimes due to mass transport effects and not due to the inherent property of the material itself.…”

“…171-172, 174-175, 178 These studies gave significant insights into the role of solvents and caution the readers that certain enhanced properties are sometimes due to mass transport effects and not due to the inherent property of the material itself. [171][172][173][174]176 However, the fundamental differences between the redox probe for heterogeneous electron transfer (HET) rate determination and HER mechanism would have limited the transfer of the findings from the studies conducted to explain or predict the HER electrocatalytic efficiency. Caution should be taken as it is necessary to note that activation of the electrode in one redox system does not imply that it will affect all system equally.…”