Hediyeh Khatibnezhad, Fabian Ambriz-Vargas, Fadhel Ben Ettouil, Christian Moreau

Thermal Spray and Multiphase Flow Laboratory, Department of Mechanical, Industrial and Aerospace Engineering, Concordia University, Montreal, QC, Canada

Titanium dioxide (TiO2), as one of the most recognized photocatalysts, allows the decomposition and removal of waste organic compounds and harmful gases from water and the atmosphere. Moreover, extensive research has been conducted to improve its efficiency in the last decades. In this work, self-doped TiO2 coatings (TiO2-x) with different oxygen content levels and anatase phase ratio were deposited by suspension plasma spraying followed by heat-treatment. UV–visible spectroscopy results showed a significant bandgap reduction of the TiO2 coatings due to the oxygen vacancies. Moreover, the role of the crystalline phase of anatase was investigated. The photocatalytic performance was evaluated by monitoring the degradation of methylene blue under visible light, and the results indicated that oxygen deficiency and higher anatase content positively affect the photocatalytic activity of self-doped TiO2 under visible light. Additionally, coatings were characterized by X-ray diffractometer, confocal laser microscope, scanning electron microscope, Raman spectroscopy, and thermogravimetric analyzer.