Neutral Red as a Redox Probe for Comparative Evaluation of Electrochemical Performance of Bismuth Modified Electrodes

Abstract

For the first time, Neutral Red (NR) has been used as a redox probe for comparative evaluation of the electrochemical performance of screen-printed carbon electrodes (SPCEs) modified with bismuth under different potentiostatic pre-plating conditions (Bi/SPCEs). It was shown that protonated NR undergoes quasi-reversible redox transformations at bare-SPCE and Bi/SPCEs in the pH range 5–6 in phosphate buffer solutions (PBS) in the potential range of (−0.2)–(−0.8) V, where bismuth is not electroactive. Bi/SPCEs have been characterized morphologically by scanning electron microscopy (SEM) and electrochemically by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) employing NR as a redox probe. The obtained SEM, CV, and EIS data are in good agreement. The highest charge transfer resistance (Rct) values (3.9 and 3.3 kΩ) were obtained at bare-SPCE and Bi/SPCE having low degree of bismuth coverage. Contrarily, the lowest Rct value (8 Ω) was recorded at Bi/SPCE, with the highest degree of bismuth coverage. CV experiments showed a significant increase in the electrochemical performances of Bi/SPCEs, whose surface is half or more covered with bismuth, in comparison to the bare-SPCE. Nickel (II) ions and formaldehyde (FM), in the form of formaldehyde hydrazone (FAH), were used as model analytes to determine the electroanalytical performance of Bi/SPCEs. A comparison of roughness factor and sensitivity toward both analytes for Bi/SPCEs with two-tailed Pearson’s criterion showed a high degree of correlation between their electrochemical and electroanalytical characteristics. The data acquired indicates that the use of NR as a redox probe may be quite helpful to control modification processes when developing novel bismuth-containing sensors.

Keywords:

• Bismuth film
• electrochemical/morphological characteristics
• neutral red
• screen-printed carbon electrodes
• stripping voltammetry

Acknowledgments

The authors are grateful to Ural Federal University, named after the first President of Russia, B. N. Yeltsin for the financial support.

Disclosure statement

The authors declare no conflicts of interest.

Authors’ contributions

Nataliya Malakhova: Conceptualization, validation, writing - review & editing.

Alexander B. Kifle: Investigation, methodology, writing - original draft and editing.

Alexandra Ivoilova: Investigation, methodology, and writing.

Nataliya Leonova: Investigation and methodology.

Alisa Kozitsina: Project administration, validation, supervision.

Additional information

Funding

This study was supported by the Ministry of Science and Higher Education of the Russian Federation (Ural Federal University Program of Development within the Priority-2030 Program).