Titanium dioxide (TiO₂) is a typical inorganic material that has an excellent photocatalytic property and a high refractive index. It is used in water/air purifiers, solar cells, white pigments, refractory materials, semiconductors, etc.; its demand is continuously increasing. In this study, anatase and rutile phase titanium dioxide is prepared using hydroxyl and carboxyl; the titanium complex and its mechanism are investigated. As a result of analyzing the phase transition characteristics by a heat treatment temperature using a titanium complex having a hydroxyl group and a carboxyl group, it is confirmed that the material properties were different from each other and that the anatase and rutile phase contents can be controlled. The titanium complexes prepared in this study show different characteristics from the titania-formation temperatures of the known anatase and rutile phases. It is inferred that this is due to the change of electrostatic adsorption behavior due to the complexing function of the oxygen sharing point, which crystals of the TiO₆ structure share.

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• Thermal Stability and Weight Reduction of Al0.75V2.82CrZr Refractory High Entropy Alloy Prepared Via Mechanical Alloying
  Minsu Kim, Hansung Lee, Byungmin Ahn
  journal of Korean Powder Metallurgy Institute.2023; 30(6): 478.     CrossRef

Composites of P25 TiO₂ and hexagonal WO₃ nanorods are synthesized through ball-milling in order to study photocatalytic properties. Various composites of TiO₂/WO₃ are prepared by controlling the weight percentages (wt%) of WO₃, in the range of 1–30 wt%, and milling time to investigate the effects of the composition ratio on the photocatalytic properties. Scanning electron microscopy, x-ray diffraction, and transmission electron microscopy are performed to characterize the structure, shape and size of the synthesized composites of TiO₂/WO₃. Methylene blue is used as a test dye to analyze the photocatalytic properties of the synthesized composite material. The photocatalytic activity shows that the decomposition efficiency of the dye due to the photocatalytic effect is the highest in the TiO₂/WO₃ (3 wt%) composite, and the catalytic efficiency decreases sharply when the amount of WO₃ is further increased. As the amount of WO₃ added increases, dye-removal by adsorption occurs during centrifugation, instead of the decomposition of dyes by photocatalysts. Finally, TiO₂/WO₃ (3 wt%) composites are synthesized with various milling times. Experimental results show that the milling time has the best catalytic efficiency at 30 min, after which it gradually decreases. There is no significant change after 1 hour.

The coupling of two semiconducting materials is an efficient method to improve photocatalytic activity via the suppression of recombination of electron-hole pairs. In particular, the coupling between two different phases of TiO₂, i.e., anatase and rutile, is particularly attractive for photocatalytic activity improvement of rutile TiO₂ because these coupled TiO₂ powders can retain the benefits of TiO₂, one of the best photocatalysts. In this study, anatase TiO₂ nanoparticles are synthesized and coupled on the surface of rutile TiO₂ powders using a microemulsion method and heat treatment. Triton X-100, as a surfactant, is used to suppress the aggregation of anatase TiO₂ nanoparticles and disperse anatase TiO₂ nanoparticles uniformly on the surface of rutile TiO₂ powders. Rutile TiO₂ powders coupled with anatase TiO₂ nanoparticles are successfully prepared. Additionally, we compare the photocatalytic activity of these rutile-anatase coupled TiO₂ powders under ultraviolet (UV) light and demonstrate that the reason for the improvement of photocatalytic activity is microstructural.

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• Refractory Metal Oxide–Doped Titanate Nanotubes: Synthesis and Photocatalytic Activity under UV/Visible Light Range
  Min-Sang Kim, Hyun-Joo Choi, Tohru Sekino, Young-Do Kim, Se-Hoon Kim
  Catalysts.2021; 11(8): 987.     CrossRef
• Effect of Surfactant on the Dispersion Stability of Slurry for Semiconductor Silicon CMP
  Hye Won Yun, Doyeon Kim, Do Hyung Han, Dong Wan Kim, Woo-Byoung Kim
  Journal of Korean Powder Metallurgy Institute.2018; 25(5): 395.     CrossRef

Pt has been widely used as catalyst for fuel cell and exhausted gas clean systems due to its high catalytic activity. Recently, there have been researches on fabricating composite materials of Pt as a method of reducing the amount of Pt due to its high price. One of the approaches for saving Pt used as catalyst is a core shell structure consisting of Pt layer on the core of the non-noble metal. In this study, the synthesis of Pt shell was conducted on the surface of TiO₂ particle, a non-noble material, by applying ultraviolet (UV) irradiation. Anatase TiO₂ particles with the average size of 20~30 nm were immersed in the ethanol dissolved with Pt precursor of H₂PtCl₆∙6H₂O and exposed to UV irradiation with the wavelength of 365 nm. It was confirmed that Pt nano-particles were formed on the surface of TiO₂ particles by photochemical reduction of Pt ion from the solution. The morphology of the synthesized Pt@TiO₂ nano-composite was examined by TEM (Transmission Electron Microscopy).

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• Photocatalytic activity of rutile TiO2 powders coupled with anatase TiO2 nanoparticles using surfactant
  Jong Min Byun, Chun Woong Park, Young In Kim, Young Do Kim
  journal of Korean Powder Metallurgy Institute.2018; 25(3): 257.     CrossRef
• Synthesis and Photo Catalytic Activity of 10 wt%, 20 wt%Li-TiO2 Composite Powders
  Hyeong-Chul Kim, Jae-Kil Han
  Journal of Korean Powder Metallurgy Institute.2016; 23(1): 33.     CrossRef