Pseudocapacitive Behavior of Protonic Niobate Nanowires in Aqueous Acidic Electrolyte

Niobium-based oxides are being increasingly evaluated as materials for energy storage applications. Additionally, the use of these oxides as cathodes in aqueous electrolytes has shown promise. Based on this, the pseudocapacitive behavior of protonic niobate nanowires in an aqueous acidic electrolyte...

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Main Authors: Adilar Gonçalves dos Santos Júnior, Jessica Gotardi, Edna Jerusa Pacheco Sampaio, Cristiano Campos Araújo, Gabriel Luiz Rasch, Antonio Marcos Helgueira de Andrade, Roberto Hübler, Andrés Cuña Suárez, Célia de Fraga Malfatti
Format: Article
Language:English
Published: MDPI AG 2025-05-01
Series:Ceramics
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Online Access:https://www.mdpi.com/2571-6131/8/2/59
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Summary:Niobium-based oxides are being increasingly evaluated as materials for energy storage applications. Additionally, the use of these oxides as cathodes in aqueous electrolytes has shown promise. Based on this, the pseudocapacitive behavior of protonic niobate nanowires in an aqueous acidic electrolyte (1 M H<sub>2</sub>SO<sub>4</sub>) was evaluated for the first time. The material was obtained in two simple sequential steps. First, hydrothermal synthesis resulted in sodium niobate; second was ionic exchange (in two concentrations of 2 M and 0.1 M HNO<sub>3</sub>), where the protonic niobate was obtained. The resulting protonic niobate was characterized by FEG-SEM, the results demonstrated that the morphology of the oxide was concentration-dependent in the ionic exchange step, and EDS analysis was used to validate the procedure. Using DRX, Raman spectroscopy, and FTIR analysis, the transformation of sodium niobate to protonic niobate was evidenced. The electrochemical tests demonstrated that the protonic niobate presented pseudocapacitive behavior when employed as the cathode in 1 M H<sub>2</sub>SO<sub>4</sub>, and the ionic exchange in 2 M HNO<sub>3</sub> promoted a better specific capacitance, reaching 119.8 mF·cm<sup>−2</sup> at a 1 mA·cm<sup>−2</sup> current density.
ISSN:2571-6131