Nb2O5 and AlNbO4 coatings formed by plasma electrolytic oxidation of niobium: synthesis, characterization, and photocatalytic activity

• Published in: Journal of materials science. Materials in electronics Vol. 35; no. 6; p. 410
• Main Authors: Stojadinović, Stevan, Radić, Nenad, Perković, Mladen
• Format: Journal Article
• Language: English
• Published: New York Springer US 01.02.2024; Springer Nature B.V
• Subjects: Aqueous solutions; Catalytic activity; Characterization and Evaluation of Materials; Chemistry and Materials Science; Coatings; Diffuse reflectance spectroscopy; Dyes; Electrolytes; Emission analysis; Europium; Europium compounds; Materials Science; Niobium oxides; Optical and Electronic Materials; Optical emission spectroscopy; Oxidation; Photocatalysis; Photocatalysts; Photodegradation; Photoelectrons; Photoluminescence; Sodium aluminate; Spectrum analysis; Substrates; Ultraviolet absorption; Ultraviolet reflection; Ultraviolet spectroscopy; X ray photoelectron spectroscopy; Zinc oxide
• ISSN: 0957-4522; 1573-482X
• DOI: 10.1007/s10854-024-12168-5

This study describes the formation of efficient photocatalysts on a niobium substrate using plasma electrolytic oxidation (PEO) in an alkaline electrolyte both with and without the addition of NaAlO 2 . The process of PEO was analyzed by using optical emission spectroscopy and real-time imaging. Scanning electron microscopy, energy-dispersive x-ray spectroscopy, x-ray diffraction, x-ray photoelectron spectroscopy, ultraviolet-visible diffuse reflectance spectroscopy, and photoluminescence were used to characterize the formed photocatalysts. Photodegradation experiments in an aqueous solution of methyl orange were conducted to assess the photocatalytic activity (PA) of formed coatings. The PA of Nb 2 O 5 coatings generated in pure alkaline electrolytes was found to be lower than that of AlNbO 4 coatings formed in alkaline electrolytes with added NaAlO 2 . The significant PA of both Nb 2 O 5 and AlNbO 4 coatings, due to their strong ultraviolet absorption, was associated with high concentrations of oxygen vacancy. After 8 h of irradiation, the PA for AlNbO 4 coating formed after 15 min in an alkaline electrolyte with 2 g/L NaAlO 2 reached around 81%. Furthermore, the study revealed that by adding ZnO and Eu 2 O 3 particles into the alkaline electrolyte with + 2 g/L NaAlO 2, coatings such as AlNbO 4 /ZnO and AlNbO 4 :Eu 3+ /Eu2 + with improved PA comparing to AlNbO 4 alone could be produced.