Abstract
Titanium dioxide is a very useful photocatalyst for the decomposition and diminution of environmental water and air pollutants. In such applications, it can be used as slurry or as immobilized coating obtained by different deposition methods. The studies performed in the last years showed that thermal spraying could be employed to elaborate TiO2 coatings with high performance for the decomposition of organic compounds. This manuscript presents a comparative study on the microstructure and photocatalytic performance of titania coatings obtained by different thermal spray techniques: atmospheric plasma spraying (APS), suspension plasma spraying (SPS) and high‐velocity oxygen fuel spray process (HVOF). Different titania powders and suspensions were used to study the influence of the feedstock materials on the coating characteristics. The deposits were mainly characterised by SEM and X‐ray diffraction. The photocatalytic performance was evaluated from the removal of nitrogen oxides. The experimental results showed that a drastic reduction of the pollutant concentration was obtained in presence of coatings elaborated by suspension plasma spraying. TiO2 coatings resulting from the spraying of agglomerated powder presentd less efficiency. That was mainly explained by the significant phase transformation from anatase to rutile that occurred in the enthalpic source during the spray processes.
Highlights
Titanium dioxide (TiO2) is an attractive material for numerous technological processes
This manuscript presents a comparative study on the microstructure and photocatalytic performance of titania coatings obtained by different thermal spray techniques: atmospheric plasma spraying (APS), suspension plasma spraying (SPS), and high-velocity oxygen fuel spray process (HVOF)
The analysis showed that the passage of the feedstock material in the enthalpic source involved the modifications of the chemical state of titanium dioxide compared to that of the initial powders
Summary
Titanium dioxide (TiO2) is an attractive material for numerous technological processes. It finds applications as gas sensors, as pigments in foodstuffs, paints, cosmetics, or pharmacology, as a corrosion resistant coating, in heterogeneous catalysis and photocatalysis, in solar cells for the production of hydrogen and electric energy, in electronic devices, and so on. Titanium dioxide can be used in the degradation of air and water pollutants, in medical sterilization, and even in cancer therapy [2,3,4]. Among the two TiO2 crystalline phases, anatase and rutile that can contribute to the photocatalysis, it is generally assumed that the anatase—the metastable phase, which by thermal treatment irreversibly turns into rutile—allows a higher-photocatalytic degradation of the pollutants. It is considered that the aforementioned difficulties concerning films and coatings can be overcome and their applications can be expanded by employing various materials as substrates
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