Volume: 4, 2025
4th International PhD Student’s Conference at the University of Life Sciences in Lublin, Poland:
ENVIRONMENT – PLANT – ANIMAL – PRODUCT
Abstract number: H016
DOI: https://doi.org/10.24326/ICDSUPL4.H016
Published online: 9 April 2025
ICDSUPL, 4, H016 (2025)
Reinterpretation of the ‘cap-pair’ rule in mixed aqueous-organic electrochemical systems containing ethanol and acetonitrile: mechanism and kinetics of the electroreduction process of Bi(III) ions
Alicja Pawlak1*, Agnieszka Nosal-Wiercińska1
1 Department of Analytical Chemistry and Instrumental Analysis, Faculty of Chemistry, Maria Curie-Sklodowska University, Marie Skłodowskiej-Curie 3, 20-031 Lublin, Poland
* Corresponding author: alicja.pawlak@mail.umcs.pl
Abstract
A very interesting area of electrochemical research is the electroreduction of metal ions in organic solvents, especially concerning electrodeposition and the production of new nanomaterials. As the world turns its attention to sustainability, scientists are exploring new ways of recovering substances and developing environmentally friendly materials. It is crucial to understand the kinetics of the reaction to properly design such systems. According to the “cap pair rule”, the kinetics of electrochemical reactions can be altered by appropriately selected organic compounds that contain sulfur or nitrogen atoms and are capable of forming coordination bonds with depolarizer ions. Although ethanol and acetonitrile are not examples of such compounds, they can affect the mechanism of electroreduction and the kinetics of the process in experimental systems. Thus, new possible applications of this principle in mixed, aqueous-organic systems have been discovered. In this work, we investigated how ethanol and acetonitrile concentrations affect the Bi(III) ions electrochemical reduction of in aqueous-chlorates(VII) solutions. We used the µAutolab electrochemical analyzer, which allows DC polarography, cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and square wave voltammetry (SWV). The mixed aqueous-organic supporting electrolytes had concentrations of ethanol and acetonitrile ranging from 10% to 50%, and the bismuth(III) ion concentration was kept at 1∙10-3 mol/dm3. Results indicate that the presence of ethanol and acetonitrile affects the path of electroreduction of Bi(III) ions, modifying the reaction mechanism for these two solvents. We’ve noticed that the reduction potential shifts toward more negative values, and there’s an increase in charge transfer resistance, which suggests that these solvents slow down the reaction and change its multi-step dynamics. Additionally, the changes at the interface between the electrode (RAgLAFE) and the solution indicate that ethanol and acetonitrile actively moderate these processes. Understanding how these factors interact could be important for developing sustainable bismuth electrodeposition technologies, particularly for environmental applications and creating modern, high-performance materials.
Keywords: electrochemistry, amalgam electrodes, Bi(III) ions, R-AgLAFE
How to cite
A. Pawlak, A. Nosal-Wiercińska, 2025. Reinterpretation of the ‘cap-pair’ rule in mixed aqueous-organic electrochemical systems containing ethanol and acetonitrile: mechanism and kinetics of the electroreduction process of Bi(III) ions. In: 4th International PhD Student’s Conference at the University of Life Sciences in Lublin, Poland: Environment – Plant – Animal – Product. https://doi.org/10.24326/ICDSUPL4.H016