Operando Raman spectroelectrochemical study of polyaniline degradation: A joint experimental and theoretical analysis. (30th November 2022)

• Record Type: Journal Article
• Authors: Nunes, Willian G.; Pires, Bruno M.; Thaines, Ericson H.N.S.; Pereira, Gabriel M.A.; da Silva, Leonardo M.; Freitas, Renato G.; Zanin, Hudson
• Is Part Of: Journal of energy storage. Volume 55:Part D(2022)
• Publication Date: 2022-11-30
• Subjects: Polyaniline -- Operando Raman -- Head-to-tail -- Voltage window -- Materials modeling; Energy storage -- Periodicals; Energy storage -- Research -- Periodicals; 621.3126
• DOI: 10.1016/j.est.2022.105770
• Languages: English
• ISSNs: 2352-152X

Abstract

Abstract: Operando Raman spectroscopy of an electrode composed of the polyaniline is performed to elucidate the fundamental polarization mechanism occurring in an electrochemical supercapacitor during a large electroactive voltage window. The polyaniline presented two distinct redox processes; the first is associated with converting the leucoemeraldine base to the emeraldine and then with the conversion of emeraldine to the pernigraniline. By operando Raman spectroscopy, the exchange of the head-to-tail polarization mechanism by forming head-to-head coupling during voltammetric was verified. In the charging process, oxidized polyaniline forms polaron and bipolaron structures, causing deprotonation, while sulfate from the electrolyte inserting in the polyaniline chain causing a balance of the electronic charge. The materials modeling was shown to analyze the effects of the applied high potential and its correlation with the p -doping/dedoping sulfate anion and water molecules in the polyaniline chain. The density functional theory using van der Wall correction (DFT + vdW) simulation elucidated tensile stress with the insertion of sulfate anion and water molecules. It was not observed any hydrogen bond between polyaniline chain and sulfate anion, which facilitate and contribute to the conductivity of polyaniline emeraldine-like structure. Graphical abstract: Unlabelled Image Highlights: Operando Raman analysis of polyaniline structure under dynamic polarization conditions was performed. Density functional theory elucidated tensile stress with the insertion of sulfate anion and water molecules. Exchange of the head-to-tail polarization mechanism by forming head-to-head coupling during cyclic voltammetric.