Archive / Volume LXXVIII 2025

Victoria LOVCHYTSKA, Yaroslav KOVALYSHYN, Oleksandr RESHETNYAK

Ivan Franko National University of Lviv, Kyryla i Mefodia Str., 6, 79005 Lviv, Ukraine
e-mail: andriy.krupak@gmail.com

DOI:

INFLUENCE OF GRAPHITE MODIFICATION BY ELECTROCHEMICAL REDUCTION OF BENZENEDIAZONIUM ON SURFACE WETTABILITY

The process of reduction of benzenediazonium tetrafluoroborate on a graphite electrode from acetonitrile solution was investigated by cyclic voltammetry. In the first cycle of the potential scan, reduction peaks are observed at potentials of about -0.07 and -0.30 V. The peak at a potential of -0.07 V corresponds to the process of reduction of diazo salt with the formation of a phenyl radical. In the subsequent cycles of potential scanning, a sharp decrease in reduction currents is observed. The results obtained indicate the possibility of modifying the graphite surface by electrochemical reduction of diazo salt.
Electrochemical modification of the surface of graphite MPG-7 was carried out in an acetonitrile solution containing 0.1 M benzenediazonium tetrafluoroborate and 0.1 M lithium perchlorate. During the process, a gradual decrease in the reduction current is observed due to surface modification by reduction products. The modification leads to the formation of a coating characterized by significant electrical resistance.
The wetting of a graphite surface modified by electrochemical reduction of benzenediazonium by solutions of aniline in hydrochloric acid was investigated. The contact angle of wetting of a solid graphite surface by solutions of aniline in hydrochloric acid was determined. The Dupre equation was used to calculate the work of cohesion, and the Dupre–Young equation was used to determine the equilibrium work of adhesion of the liquid. Electrochemical modification of the graphite surface significantly improves its wettability compared to the unmodified surface. Even in the case of pure water, the average value of cos θ = 0.44, which is somewhat higher compared to the unmodified surface (cos θ = 0.32). An increase in the concentration of acid and aniline leads to an increase in cos θ. The best wettability was achieved at aniline concentration of 1.0–2.0 N and acid – 3.0 N. The results obtained can be explained by the surface-inactive properties of hydrochloric acid and the surface-active properties of aniline hydrochloride. At high concentrations of aniline, the adsorption of the phenylammonium cation occurs on the graphite surface. In this case, it is obvious that the phenyl group will be oriented towards the surface, and the amine group towards the solution. The presence of phenyl groups grafted to the surface will facilitate this process.
Based on the results of determining the contact angles of wetting, the values of the work of adhesion (Wа) and cohesion (Wс) were calculated. For water, the work of adhesion and cohesion are equal to 0.105 and 0.146 J/m2, respectively. An increase in the aniline concentration leads to a decrease in the work of cohesion, which is due to a decrease in the surface tension of solutions. The work of adhesion of solutions to the graphite surface shows a general tendency to increase with increasing aniline concentration, although in the case of 3.0 n HCl, the highest work value is observed at aniline concentration of 0.5 n.
Electrochemical reduction of diazonium salts is a promising approach for modifying the graphite surface. This can be useful for creating specific materials that can be used in the development of current sources, supercapacitors, and sensors.

Keywords: benzenediazonium tetrafluoroborate, graphite, aniline, contact angle.

References:

1. Hong X., Fu J., Liu Y., Li S., Wang X., Dong W., Yang S. Recent progress on graphene/polyaniline composites for high-performance supercapacitors. Mater. 2019. Vol. 12(9). No. 1451. (https://doi.org/10.3390/ma12091451).
2. Goswami S., Nandy S., Fortunato E., Martins R. Polyaniline and its composites engineering: a class of multifunctional smart energy materials. J. Solid State Chem. 2022. Vol. 317. P. 123679. https://doi.org/10.1016/j.jssc.2022.123679. 3. Balqis F., Prakoso B., Hawari N. H., Eldona C., Sumboja A. Recent development of polyaniline/graphene composite electrodes for flexible supercapacitor devices. Chem. Nano Mater. 2022. Vol. 8. P. 950–963. https://doi.org/10.1002/cnma.202200151. 4. Mahato N., Singh S., Faisal M., Sreekanth TVM, Majumder S., Yoo K., Kim J. Polycrystalline phases grown in-situ engendering unique mechanism of charge storage in polyaniline-graphite composite. Synth. Met. 2023. Vol. 299. 117463. https://doi.org/10.1016/j.synthmet.2023.117463. 5. Mustafa Z., Ghadai R.K., Pradhan B.B., Swain B.P., Biswas J., Kumar D. Recent advances in polyaniline/graphene nanocomposites for supercapacitor applications: Synthesis, properties, and future directions. Surf. Interfaces. 2024. Vol. 17. 100316. https://doi.org/10.1016/j.rsurfi.2024.100316. 6. Mahinnezhad S., Izquierdo R., Shih A. Fully Printed pH Sensor based on Polyaniline/Graphite Nanocomposites. J. Electrochem. Soc. 2023. Vol. 170. P. 1−7. https://doi.org/10.1149/1945-7111/acb5c3. 7. Das D., Das J., Deb K., Chakraborty S., Saha B. A low-cost flexible material system made of PANI/graphite for resistive detection and quantitative determination of urea. Mater. Chem. Phys. 2023. Vol. 301. 127573. https://doi.org/10.1016/j.matchemphys.2023.127573. 8. Das D., Das J., Debnath A. Polyaniline-graphite on cellulose substrate: a flexible, low-cost, use-and-throw sensor for glucose concentration detection. Cellulose. 2023. Vol. 30. P. 6423–6433. https://doi.org/10.1007/s10570-023-05286-6. 9. Ghanbari K., Mousavi M. F., Shamsipur M., Karami H. Synthesis of polyaniline/graphite composite as a cathode of Zn-polyaniline rechargeable battery. J. Power Sourc. 2007. Vol. 170. P. 513−519. https://doi.org/10.1016/j.jpowsour.2007.02.090. 10. Hou J., Liu S., Jiang X., Waterhouse G. I. N., Zhang Z.-M., Yu L.-m. Polyaniline/graphite carbon nitride composite coatings with outstanding photo-induced anodic antifouling and antibacterial properties under visible light. Prog. Org. Coat. 2021. Vol. 154. Art. 106203. https://doi.org/10.1016/j.porgcoat.2021.106203. 11. Oladele I. O., Adelani S. O., Taiwo A. S., Akinbamiyorin I. M., Olanrewaju O. F., Orisawayi A. O. Polymer-based nanocomposites for supercapacitor applications: a review on principles, production and products. RSC Adv. 2025. Vol. 15. P. 7509–7534. https://doi.org/10.1039/D4RA08601E. 12. Jiang Y., Ji J., Huang L., He C., Zhang J., Wang X., Yang Y. One-pot mechanochemical exfoliation of graphite and in situ polymerization of aniline for the production of graphene/polyaniline composites for high-performance supercapacitors. RSC Adv. 2020. Vol. 10. P. 44688–44698. https://doi.org/10.1039/D0RA08450F. 13. Atiqah T. N., Tan S. J., Foo K. L., Supri A. G., Bakri A.M.M., Liew Y. M. Effect of graphite loading on properties of polyaniline/graphite composites. Polym. Bull. 2018. Vol. 75. P. 209–220. https://doi.org/10.1007/s00289-017-2031-1. 14. Kovalyshyn Y., Konovska M., Milanese C., Saldan I., Serkiz R. at al. Electrochemical Properties of Composites Synthesized from Polyaniline and Modified MWCNT. Chem. Chem. Technol. 2017. Vol. 11. P. 261–269. https://doi.org/10.23939/chcht11.03.261. 15. Konwer S., Pokhrel B., Dolui S. K. Synthesis and Characterization of Polyaniline/Graphite Composites and Study of Their Electrical and Electrochemical Properties. J. Appl. Polym. Sci. 2010. Vol. 116. P. 1138–1145. https://doi.org/10.1002/app.31633. 16. Wu X., Qi S., He J., Duan G. Polyaniline/Graphite Nanosheets Composites and its Conducting Properties. Polym. Polym. Composite. 2010. Vol. 18. P. 23−29. https://doi.org/10.1177/096739111001800103. 17. Konwer S., Gogoi J. P., Kalita A., Dolui S. K. Synthesis of expanded graphite filled polyaniline composites and evaluation of their electrical and electrochemical properties. J. Mater. Sci: Mater. Electron. 2011. Vol 22. P. 1154–1161. https://doi.org/10.1007/s10854-010-0276-7. 18. Internet resource: https://graphite.in.ua/ua/p115810-grafit-mpg.html. 19. Zhang G., Walker M., Unwin P. Low-voltage voltammetric electrowetting of graphite surfaces by ion intercalation/deintercalation. Langmuir. 2016. Vol. 32. P. 7710–7717. https://doi.org/10.1021/acs.langmuir.6b01506. 20. Hong H.-G., Porter M. Signal enhancement for electrochemical detection at glassy carbon electrode modified with phenyl layer. J. Electroanal. Chem. 2005. Vol. 578. P. 113–119. https://doi.org/10.1016/j.jelechem.2004.12.027. 21. Kovalyshyn Ya., Lovchytska V. Study of the graphite MPG-7 surface wetting with aqueous solutions of aniline salts. Visnyk Lviv Univ., Ser. Khim. 2024. Vol. 65. P. 335–343. (in Ukrainian). http://dx.doi.org/10.30970/vch.6501.335. 22. Papaderakis A. A., Ejigu A., Yang J., Elgendy A., Radha B., Keerthi A., Juel A., Dryfe R. A. W. Anion intercalation into graphite drives surface wetting. J. Am. Chem. Soc. 2023. Vol. 145. P. 8007–8020. https://doi.org/10.1021/jacs.2c13630.