Enhanced Photocatalytic Activity of TiO2 Coatings by Heat Treatment in Carbon Powder

2015 ◽  
Author(s):  
Sujun Guan ◽  
Liang Hao ◽  
Kohei Miyazawa ◽  
Yun Lu ◽  
Hiroyuki Yoshida ◽  
...  
Keyword(s):  
Thin Films ◽  
Heat Treatment ◽  
Photocatalytic Activity ◽  
Band Gap ◽  
Carbon Powder ◽  
Fiber Morphology ◽  
Rutile Tio2 ◽  
Micro Cracks ◽  
Nano Fiber ◽  
Tio2 Coatings

The heat treatment in carbon powder is a safe and effective strategy to enhance the photocatalytic activity of titanium dioxide (TiO2) coatings. Firstly, Ti coatings were prepared by mechanical coating operation with Ti powder on alumina balls. Secondly, the target TiO2 coatings were prepared using the prepared Ti coatings by the multi-heat treatment (pretreatment in carbon powder, oxidation in air and reduction in carbon powder). During the pretreatment, thin films of Ti2CO and micro-cracks form in the surface of the Ti coatings. The formed thin films and micro-cracks are helpful for forming a nano-fiber morphology of rutile TiO2, during the subsequent oxidation. During the reduction, oxygen vacancies generated in the lattice of rutile TiO2 are in favor of narrowing the band gap. The target TiO2 coatings with a nano-fiber morphology and the narrowed band gap, effectively enhances the photocatalytic activity by more than 3 times, compared with the pristine TiO2 coatings.

Influence of carbon atmosphere on surface morphology and photocatalytic activity of TiO2 coatings by multi-heat treatment

2015 ◽  
Vol 27 (4) ◽  
pp. 3873-3879 ◽  
Author(s):  
Sujun Guan ◽  
Liang Hao ◽  
Hiroyuki Yoshida ◽  
Hiroshi Asanuma ◽  
Fusheng Pan ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Photocatalytic Activity ◽  
Surface Morphology ◽  
Tio2 Coatings

Fabrication and Characterization of Photocatalyst Coatings by Heat Treatment in Carbon Powder for TiC Coatings

2017 ◽  
Vol 263 ◽  
pp. 137-141
Author(s):  
Su Jun Guan ◽  
Liang Hao ◽  
Hiroyuki Yoshida ◽  
Hiroshi Asanuma ◽  
Fu Sheng Pan ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Photocatalytic Activity ◽  
Visible Light ◽  
Oxygen Vacancies ◽  
Treatment Temperature ◽  
Carbon Powder ◽  
Treatment Conditions ◽  
Fabrication And Characterization ◽  
Mechanical Coating

Photocatalyst coatings on alumina (Al2O3) balls had been successfully fabricated by mechanical coating technique, with titanium carbide (TiC) powder and subsequent heat treatment in carbon powder. The effect of heat treatment conditions in carbon powder on the formed compounds, surface morphology and photocatalytic activity of photocatalyst coatings was investigated. XRD results show that the formed compounds change with increasing the heat treatment temperature in carbon powder, and rutile TiO2 on the surface of TiC coatings at 1073 K and 1173 K. The generated oxygen vacancies confirmed by XPS measurement, are in favor of narrowing band gap to enhance the visible-light photocatalytic activity of photocatalyst coatings. The photocatalytic activity of photocatalyst coatings has been effectively enhanced, and the samples fabricated at 1073 K and 1173 K for 2 h show higher activity. The fabrication strategy provides us a facile preparation procedure of visible-light responsive photocatalyst coatings.

scholarly journals A Review on the Pathways of the Improved Structural Characteristics and Photocatalytic Performance of Titanium Dioxide (TiO2) Thin Films Fabricated by the Magnetron-Sputtering Technique

Catalysts ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 598 ◽  
Author(s):  
Yu-Hsiang Wang ◽  
Kazi Hasibur Rahman ◽  
Chih-Chao Wu ◽  
Kuan-Chung Chen
Keyword(s):  
Thin Films ◽  
Refractive Index ◽  
Titanium Dioxide ◽  
Photocatalytic Activity ◽  
Magnetron Sputtering ◽  
Band Gap ◽  
Vapor Deposition ◽  
Degree Of Crystallinity ◽  
Tio2 Films ◽  
Tio2 Thin Films

Titanium dioxide (TiO2) thin films are used for a broad range of applications such as wastewater treatment, photocatalytic degradation activity, water splitting, antibacterial and also in biomedical applications. There is a wide range of synthesis techniques for the deposition of TiO2 thin films, such as chemical vapor deposition (CVD) and physical vapor deposition (PVD), both of which are well known deposition methods. Layer by layer deposition with good homogeneity, even thickness and good adhesive nature is possible by using the PVD technique, with the products being used for photocatalytic applications. This review studies the effects of magnetron sputtering conditions on TiO2 films. This innovative technique can enhance the photocatalytic activity by increasing the thickness of the film higher than any other methods. The main purpose of this article is to review the effects of DC and RF magnetron sputtering conditions on the preparation of TiO2 thin films for photocatalysis. The characteristics of TiO2 films (i.e., structure, composition, and crystallinity) are affected significantly by the substrate type, the sputtering power, the distance between substrate and target, working pressure, argon/oxygen ratio, deposition time, substrate temperature, dopant types, and finally the annealing treatment. The photocatalytic activity and optical properties, including the degree of crystallinity, band gap (Eg), refractive index (n), transmittance (T), and extinction coefficient (k), of TiO2 films are dependent on the above- mentioned film characteristics. Optimal TiO2 films should have a small particle size, a strong degree of crystallinity, a low band gap, a low contact angle, a high refractive index, transmittance, and extinction coefficient. Finally, metallic and nonmetallic dopants can be added to enhance the photocatalytic activity of TiO2 films by narrowing the band gap.

Preparation of Well-Ordered TiO2 Nanotube Arrays by Electrochemical Anodization of Titanium Foil in Neutral Electrolytes

2011 ◽  
Vol 233-235 ◽  
pp. 2047-2050
Author(s):  
Chao Wang ◽  
Da Chen ◽  
Shu Liu ◽  
Xia Ni Huang ◽  
Yue Xiang Huang ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Photocatalytic Activity ◽  
Solar Energy ◽  
Band Gap ◽  
High Performance ◽  
Diffuse Reflectance ◽  
Anatase Phase ◽  
Titanium Foil ◽  
Electrochemical Anodization ◽  
Nanotube Arrays

To obtain high performance TiO2nanotube arrays (TNAs)-based material is interesting because of its wide applications in photocatalysis field such as solar energy conversion, photocatalysis and sensors. In the present work, the well-ordered TNAs were prepared by electrochemical anodization of titanium foil in the SO42−/F−based electrolyte under 20 V for 2 h during which the Ti foil and Pt wire were used as anode and cathode, respectively. The FESEM results showed that the as-obtained TNAs were well-aligned on Ti substrate with ~ 1.5 μm in length and ~ 100 nm pore in diameter. The XRD results indicated that the as-formed TNAs was in the form of amorphous and could be transformed into crystalline anatase phase under the heat treatment at 450 °C. Meanwhile, the UV-vis diffuse reflectance spectra demonstrated that the band-gap of the obtained TNAs was narrower than the commercial TiO2nanoparticles, indicating a better photocatalytic activity of the as-prepared TNAs over the commercial TiO2nanoparticles.

scholarly journals Thickness Dependent on Photocatalytic Activity of Hematite Thin Films

2012 ◽  
Vol 2012 ◽  
pp. 1-6 ◽  
Author(s):  
Yen-Hua Chen ◽  
Kuo-Jui Tu
Keyword(s):  
Thin Films ◽  
Photocatalytic Activity ◽  
Film Thickness ◽  
Visible Light ◽  
Band Gap ◽  
Visible Light Irradiation ◽  
Hexagonal Structure ◽  
Light Irradiation ◽  
Light Illumination ◽  
Photocatalytic Ability

Hematite (Fe2O3) thin films with different thicknesses are fabricated by the rf magnetron sputtering deposition. The effects of film thicknesses on the photocatalytic activity of hematite films have been investigated. Hematite films possess a polycrystalline hexagonal structure, and the band gap decreases with an increase of film thickness. Moreover, all hematite films exhibit good photocatalytic ability under visible-light irradiation; the photocatalytic activity of hematite films increases with the increasing film thickness. This is because the hematite film with a thicker thickness has a rougher surface, providing more reaction sites for photocatalysis. Another reason is a lower band gap of a hematite film would generate more electron-hole pairs under visible-light illumination to enhance photocatalytic efficiency. Experimental data are well fitted with Langmuir-Hinshelwood kinetic model. The photocatalytic rate constant of hematite films ranges from 0.052 to 0.068 min-1. This suggests that the hematite film is a superior photocatalyst under visible-light irradiation.

Band gap coupling in photocatalytic activity in ZnO–TiO2 thin films

2012 ◽  
Vol 108 (2) ◽  
pp. 291-297 ◽  
Author(s):  
E. García-Ramírez ◽  
M. Mondragón-Chaparro ◽  
O. Zelaya-Angel
Keyword(s):  
Thin Films ◽  
Photocatalytic Activity ◽  
Band Gap ◽  
Tio2 Thin Films ◽  
Gap Coupling
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