Highly ordered nanotubular niobium oxide obtained by self-organizing anodization: A study of capacitive behavior. Issue 17 (1st September 2022)

• Record Type: Journal Article
• Authors: Pacheco Sampaio, Edna Jerusa; Antonini, Leonardo Marasca; dos Santos Júnior, Adilar Gonçalves; de Andrade, Antonio Marcos Helgueira; de Fraga Malfatti, Célia; Hubler, Roberto; Aguzzoli, Cesar
• Is Part Of: Ceramics international. Volume 48:Issue 17(2022)
• Page Start: 25424
• Page End: 25430
• Publication Date: 2022-09-01
• Subjects: Niobium oxide nanotubes -- Supercapacitor -- Capacitive behavior -- Anodization; Ceramics -- Periodicals; Céramique industrielle -- Périodiques; Ceramics; Periodicals; Electronic journals; 666
• DOI: 10.1016/j.ceramint.2022.05.219
• Languages: English
• ISSNs: 0272-8842

Abstract

Abstract: Transition metal oxide nanotubes such as niobium have attracted wide scientific attention due to their unique properties such as high ionic mobility and large specific surface area. This study investigates the capacitive behavior of nanotubular niobium oxide obtained under extremely mild anodization conditions, aiming its application in supercapacitors. The nanotubular niobium oxide was obtained by potentiostatic anodization at 90 V at room temperature, in a glycerol electrolyte containing 0.4 M NH4 F and 0.9% H2 O. Field Emission Gun Scanning Electron Microscopy analysis (FEG-SEM) was employed to perform morphological characterization. The capacitive behavior of the obtained material was investigated by cyclic voltammetry and galvanostatic charge/discharge in a three-electrode system. The neutral aqueous electrolyte used was 1 M Na2 SO4, in a potential window from −0.2 to −1.2 V vs. Ag/AgCl and 1 M H2 SO4 as an acid aqueous electrolyte in a potential window from −0.25 to −0.75 V vs Ag/AgCl. The FEG-SEM images revealed the presence of a self-organized highly ordered nanotubular niobium oxide layer on niobium substrate. Appreciable capacitance values of 20 mF cm −2 and 103 mF cm −2 were achieved in Na2 SO4 and H2 SO4 electrolytes, respectively. This great capacitive response can be associated with a large surface area achieved through the nanostructured oxide layer as well as the morphology of vertically aligned nanotubes that promote a directional ions transport, which, consequently, improves the capacitive performance. Besides, the results showed a superior performance, in terms of capacitance modulus and stability, for nanotubular niobium oxide in H2 SO4 electrolytes. The results obtained in this study highlight the great potential of the self-organized highly ordered nanotubular niobium oxide for application as a supercapacitor electrode.