FexCo1−xWO4 films on titanium: plasma electrolytic synthesis, optical, electrochemical and photocatalytic properties

• Published in: Journal of materials science. Materials in electronics 2023-10, Vol.34 (28), p.1973, Article 1973
• Main Authors: Budnikova, Yu. B., Vasilyeva, M. S., Lukiyanchuk, I. V., Egorkin, V. S., Ustinov, A. Yu, Kuryavyi, V. G., Shlyk, D. H.
• Format: Article
• Language: English
• Subjects: Anatase; Catalytic activity; Characterization and Evaluation of Materials; Charge transfer; Chemistry and Materials Science; Composite materials; Dyes; Electrochemical impedance spectroscopy; Electrolytes; Ethylenediaminetetraacetic acids; Light irradiation; Materials Science; N-type semiconductors; Nyquist plots; Optical and Electronic Materials; Optical properties; Oxidation; Photocatalysis; Photodegradation; Photoelectrons; Spectrum analysis; Titanium; Titanium dioxide; Ultraviolet radiation; X ray photoelectron spectroscopy
• ISSN: 0957-4522; 1573-482X
• DOI: 10.1007/s10854-023-11408-4

Fe x Co 1− x WO 4 films on the titanium were formed by one-step plasma electrolytic oxidation in tungstate electrolytes containing Fe(II)-EDTA and/or Co(II)-EDTA anions. The resulting composites were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), and X-ray photoelectron spectroscopy (XPS), diffuse reflection, and electrochemical impedance spectroscopy (EIS). All formed coatings contain TiO 2 in the anatase modification and orthorhombic WO 3 . The oxide layers obtained in a tungstate electrolyte with the addition of only Co(II)-EDTA ions also include CoWO 4 . Based on Mott–Schottky plots all samples show a positive slope, indicating the behavior of an n-type semiconductor. For the composites obtained, the values of the band gap determined by the Tauc method for direct allowed transitions are 2.5–2.9 eV. The resulting composites exhibit photocatalytic activity in the degradation of methyl orange (10 mg/L, pH 6.8, С(Н 2 О 2 ) = 10 mmol/L) under UV and visible light irradiation. The highest MO degradation reaches 80% in the presence of Ti/W/Co composite under UV light. According to the Nyquist plots, the most active samples have the lowest resistance to charge transfer.