Detailed Spectroscopic and Structural Analysis of TiO₂/WO₃ Composite Semiconductors

Abstract

WO3-TiO2 composite materials were obtained using commercial titania (Evonik Aeroxide P25) and hydrothermally crystallized WO3. Different ratios of TiO2/WO3 were investigated, starting at 1 wt.% of WO3 to 50 wt.%. The morphology of WO3 was of the star-like type, and its structure is basically composed of monoclinic crystalline phase. All spectroscopic characteristics of the composites and their derived data (band-gap energy value, light absorption threshold, and IR specific bands) directly varied with the increase of the WO3 content. However, the oxalic acid photodegradation achieved under UV light reached the highest yield for 24 wt.% WO3 content, a result that was attributed to the charge separation efficiency and the surface hydrophilicity. The latter mentioned reason points out the crucial importance of the surface quality of the investigated structure in photocatalytic tests.

Effect of Thermal Treatment on the Phase Composition and Surface Properties of WO3‐TiO2 Nanocomposites Synthesized via Hydro‐Thermal Method

“…The analysis of IR spectra revealed the presence of specific signals of TiO 2 and WO 3 without any major changing trend. The peak in the 400–410 cm −1 range was due to stretching vibrations of Ti−O and TivO−Ti [57,58] . The main peak near 1000–1100 cm −1 in all the samples was related to different W−O−W stretching vibrations, particularly W=O bonds near 1060 cm −1 [59] .…”

TiO2 based nanopowder coatings over stainless steel plates for UV‐C photocatalytic degradation of methylene blue

“…As only AW10 nm contains 6% WO 3 , to minimize the size influence and to keep a percentage of WO 3 , 40% of AW10 nm was used to make a WO 3 content of 2.4%. In the literature, after a comparison of WO 3 addition from 1%‐50%, it was found that 24% WO 3 content in a TiO 2 /WO 3 composite contributed the best photocatalytic activity in oxalic acid degradation …”

Sensor surface via inspiration from Nature: The specific case of electron trapping in TiO2/WO3(∙0.33H2O) and reaction center/WO3(∙0.33H2O) systems

“…The answer lies mainly in the previously mentioned energetic criteria. Coupling of WO 3 with TiO 2 -in a well-determined ratio, using the corresponding method of preparation -either physical mixing [18] or pH adjustment corresponding to the surface charge of the components of the composite [19] is considered as an efficient way to prepare composites with great sensorial and photocatalytic efficiency (in certain cases, such as phenol, methyl-orange) [20][21]. According to Lee and coworkers, the excitation of TiO 2 /WO 3 composites triggers the following steps [22]: (i) the excitation of semiconductors and the formation of charge carriers, (ii) charge-transfer (WO 3 (h + , e -) / TiO 2 (h + , e -) → WO 3 (e -) / TiO 2 (h + )), (iii) re-oxidation of W 5+ to W 6+ due to the involvement of molecular O 2 .…”