PEO–Hydrothermal Engineering of VOₓ/TiO₂ Photocatalysts for Efficient Visible-Light Degradation of Methylene Blue

Zaheri, Shiva; Fattah-alhosseini, Arash; Karbasi, Minoo; Kaseem, Mosab

doi:10.22059/jufgnsm.2026.01.09

PEO–Hydrothermal Engineering of VOₓ/TiO₂ Photocatalysts for Efficient Visible-Light Degradation of Methylene Blue

Document Type : Research Paper

Authors

Shiva Zaheri ¹

Arash Fattah-alhosseini ¹

Minoo Karbasi ¹

Mosab Kaseem ²

¹ Bu-Ali Sina University, Department of Materials Engineering, Faculty of Engineering, Hamedan, Iran

² Sejong University, Department of Nanotechnology and Advanced Materials Engineering, Seoul 05006, Republic of Korea

10.22059/jufgnsm.2026.01.09

Abstract

Visible-light-driven photocatalysis plays a crucial role in sustainable wastewater treatment. In this work, Methylene blue (MB) was employed as a model organic pollutant to evaluate the photocatalytic performance of VOₓ/TiO₂ composite coatings fabricated via plasma electrolytic oxidation (PEO) followed by hydrothermal treatment. The hydrothermal temperature (160–200 °C) was systematically investigated as the key operating variable. Structural and optical properties were analyzed using XRD, SEM, UV–Vis DRS, and PL spectroscopy. The optimized sample synthesized at 180 °C exhibited an apparent optical band gap of ~1.75 eV and a pronounced red-shift compared to pristine TiO₂ (~3.2 eV). Under visible-light irradiation (54 mW cm⁻²), the 180 °C sample achieved 85% methylene blue degradation within 2.5 h, compared to only 23% for pristine TiO₂, corresponding to a 62 percentage-point improvement. Moreover, the apparent reaction rate constant increased from 2×10⁻³ to 11×10⁻³, representing an approximately 5.5-fold enhancement. The degradation efficiency increased from 73% at 160 °C to 85% at 180 °C but decreased to 58% at 200 °C, confirming the existence of an optimal hydrothermal temperature window. The enhanced activity is attributed to improved crystallinity, extended visible-light absorption, and suppressed charge recombination at the VOₓ/TiO₂ interface. These findings highlight the importance of hydrothermal temperature control in engineering efficient visible-light photocatalysts.

Keywords

Plasma electrolytic oxidation (PEO)

VOₓ/TiO₂ composite

Methylene blue (MB)

Photocatalytic activity

Hydrothermal

S. Sakthivel, M.C. Hidalgo, D.W. Bahnemann, S.-U. Geissen, V. Murugesan, A. Vogelpohl, A Fine Route to Tune the Photocatalytic Activity of TiO2, Appl. Catal. B 63 (2006) 31–40.
J. Jeon, D.H. Kweon, B.J. Jang, M.J. Ju, J. Baek, Enhancing the Photocatalytic Activity of TiO2 Catalysts, Adv. Sustain. Syst. 4 (2020).
J.C. Crittenden, J. Liu, D.W. Hand, D.L. Perram, Photocatalytic Oxidation of Chlorinated Hydrocarbons in Water, Water Res. 31 (1997) 429–438.
F. Ren, H. Li, Y. Wang, J. Yang, Enhanced Photocatalytic Oxidation of Propylene over V-Doped TiO2 Photocatalyst, Appl. Catal. B 176–177 (2015) 160–172.
X. Zhou, J. Wu, Q. Li, Y. Qi, Z. Ji, P. He, X. Qi, P. Sheng, Q. Li, J. Ren, Improved Electron–Hole Separation and Migration in V2O5/Rutile–Anatase Photocatalyst System,Chem. Eng. J. 330 (2017) 294–308.
J. Sun, X. Li, Q. Zhao, J. Ke, D. Zhang, Novel V2O5/BiVO4/TiO2 Nanocomposites with High Visible-Light Photocatalytic Activity, J. Phys. Chem. C 118 (2014) 10113–10121.
M. Ghosh, J. Liu, S.S.C. Chuang, S.C. Jana, Hierarchical V2O5 Nanorods on TiO2 Nanofibers, ChemCatChem 10 (2018) 3305–3318.
Y. Wang, Y.R. Su, L. Qiao, L.X. Liu, Q. Su, C.Q. Zhu, X.Q. Liu, One-Dimensional TiO2/V2O5 Heterostructures, Nanotechnology 22 (2011) 225702.
Q. Su, J. Zhang, Y. Wang, M. Yu, C. Zhu, W. Lan, X. Liu,Effect of Morphology on V2O5/TiO2 Photocatalysts, J. Phys. Chem. Solids 74 (2013) 1475–1481.
M. Motola, L. Satrapinskyy, M. Čaplovicová, T. Roch, M. Gregor, Enhanced Photocatalytic Activity of V-Doped TiO2 Nanotubes, Appl. Surf. Sci. 434 (2018) 1257–1265.
T. Karras, M. Aittala, T. Aila, S. Laine, Alias-Free Generative Adversarial Networks, arXiv preprint arXiv:2205.04046 [cs.CV] (2022).
V.T. Truong, P.N.M. Le, M.V. Le, Influence of Hydrothermal Parameters on Photocatalytic Activity of BiVO4 for Degradation of Methylene Blue, Indonesian Journal of Chemistry 25 (2025) 744–759.
A.L. Yerokhin, X. Nie, A. Leyland, A. Matthews, S.J. Dowey, Plasma Electrolysis for Surface Engineering, Surf. Coat. Technol. 122 (1999) 73–93.
A.L. Yerokhin, A. Matthews, Plasma Electrolytic Oxidation of Aluminium Alloys, Thin Solid Films 515 (2007) 147–158.
M. Kaseem, Y.G. Ko, Recent Advances in Plasma Electrolytic Oxidation, Coatings 9 (2019) 283.
J. Livage, Hydrothermal Synthesis of Vanadium Oxides, Materials 3 (2010) 4175–4195.
M. Tang, Y. Xia, D. Yang, et al., Hydrothermal Parameters on TiO2 Structure, Materials 14 (2021) 5674.
A. Saberyoun, A. Fattah-alhosseini, M. Karbasi, R. Hosseini, M. Kaseem, Visible-Light Photocatalytic Cu/TiO2 Coatings, Ceram. Int. 50 (2024) 31313–31325.
H. Zhang, D. Meng, B. Fu, H. Fan, R. Cai, P.P. Fu, X. Wu, Separation of charge carriers and generation of reactive oxygen species by TiO 2 nanoparticles mixed with differently-coated gold nanorods under light irradiation, Journal of Environmental Science and Health, Part C 37 (2019) 81–98.
A. Nellessen, A. Schaefer, A. Martinelli, et al., Vanadium Loading on Titania, J. Phys. Chem. C 128 (2024) 2894–2908.
J. Vujančević, P. Andričević, V. Djokić, et al.,Vanadium-Oxide Modified TiO2, Catalysts 13 (2023) 352.
G.-W. Lin, J.-S. Chen, W. Tseng, F.-H. Lu, Anatase TiO2 Coatings by PEO, Surf. Coat. Technol. 357 (2019) 28–35.
A.L. Patterson, The Scherrer Formula for X-Ray Particle Size Determination, Phys. Rev. 56 (1939) 978–982.
A. Hoseini, B. Yarmand, Fe2O3/TiO2 via PEO, J. Nanopart. Res. 22 (2020) 312.
M. Laghaei, M. Ghasemian, M.R.G. Ferdowsi, et al., Titanium–Vanadium Oxides, J. Colloid Interface Sci. 646 (2023) 11–24.
K. Schneider, Electronic Structure of Vanadium Oxides, J. Mater. Sci.: Mater. Electron. 31 (2020) 10478–10488.
C. Huang, L. Chen, H. Li, et al., Bi2WO6 Photocatalysis, RSC Adv. 9 (2019) 27768–27779.
S. Lettieri, M. Pavone, A. Fioravanti, et al., Charge Carrier Processes in TiO2, Materials 14 (2021) 1645.
L. Kernazhitsky, V. Shymanovska, T. Gavrilko, et al., Photoluminescence of TiO2, J. Lumin. 166 (2015) 253–258.
Y. Wang, Q. Su, C.H. Chen, et al., V2O5 Nanomaterials Growth, J. Phys. D: Appl. Phys. 43 (2010) 185102.