• Title, Summary, Keyword: $TiO_2$ Nanoparticles

Search Result 371, Processing Time 0.043 seconds

Synthesis and Photocatalytic Properties of SnO2-Mixed and Sn-Doped TiO2 Nanoparticles

  • Choi, Hong-Goo;Yong, Seok-Min;Kim, Do-Kyung
    • Korean Journal of Materials Research
    • /
    • v.22 no.7
    • /
    • pp.352-357
    • /
    • 2012
  • $SnO_2$-mixed and Sn-doped $TiO_2$ nanoparticles were synthesized via a hydrothermal process. $SnO_2$-mixed $TiO_2$ nanoparticles prepared in a neutral condition consisted of anatase $TiO_2$ nanoparticles(diamond shape, ~25 nm) and cassiterite $SnO_2$ nanoparticles(spherical shape, ~10 nm). On the other hand, Sn-doped $TiO_2$ nanoparticles obtained under a high acidic condition showed a crystalline phase corresponding to rutile $TiO_2$. As the Sn content increased, the particle shape changed from rod-like(d~40 nm, 1~200 nm) to spherical(18 nm) with a decrease in the particle size. The peak shift in the XRD results and a change of the c-axis lattice parameter with the Sn content demonstrate that the $TiO_2$ in the rutile phase was doped with Sn. The photocatalytic activity of the $SnO_2$-mixed $TiO_2$ nanoparticles dramatically increased and then decreased when the $SnO_2$ content exceeded 4%. The increased photocatalytic activity is mainly attributed to the improved charge separation of the $TiO_2$ nanoparticles with the $SnO_2$. In the case of Sn-doped $TiO_2$ nanoparticles, the photocatalytic activity increased slightly with the Sn content due most likely to the larger energy bandgap caused by Sn-doping and the decrease in the particle size. The $SnO_2$-mixed $TiO_2$ nanoparticles generally exhibited higher photocatalytic activity than the Sn-doped $TiO_2$ nanoparticles. This was caused by the phase difference of $TiO_2$.

Phase Transformation Characteristics of Combustion-Synthesized TiO2 Nanoparticles (연소합성 TiO2 나노입자의 고온 상변환 특성에 관한 연구)

  • Choi, Shang-Min;Lee, Gyo-Woo
    • Transactions of the Korean Society of Mechanical Engineers B
    • /
    • v.32 no.3
    • /
    • pp.224-230
    • /
    • 2008
  • In this article, $TiO_2$ nanoparticles were synthesized by using $O_2$-enriched coflow, hydrogen, diffusion flames. We investigated the thermal stability of the flame-synthesized $TiO_2$ nanoparticles by examining the crystalline structures of the nanoparticles. Also, the results were compared with those of commercial P-25 nanoparticles. $TiO_2$ nanoparticles, which were spherical with diameters approximately ranging from 30 to 60nm, were synthesized. From the XRD analyses, about 96wt% of the synthesized nanoparticles were anatase-phase. After the heat-treatment at $800^{\circ}C$ for 30 minutes, the synthesized $TiO_2$ nanoparticles showed no significant changes of their shapes and crystalline phases. On the other hand, most of the commercial particles sintered with each other and changed to the rutile-phase. Based on the result of XRD analysis it is believed that the flame-synthesized $TiO_2$ nanoparticles have higher thermal stability at $800^{\circ}C$ than the commercial particles.

Enhancing photoluminescence of Au - TiO2 nanoparticles using Drude model

  • Dang, Diem Thi-Xuan;Vu, Thi Hanh Thu
    • Journal of IKEEE
    • /
    • v.21 no.3
    • /
    • pp.288-296
    • /
    • 2017
  • The enhancement of photoluminescence of Au-$TiO_2$ nanoparticles by surface plasmon resonance has been studied extensively by experiment in recent years. For the purpose of optimizing the photoluminescence property of Au-$TiO_2$ nanoparticles, the manufacturing parameters related to the Au nanoparticles and $TiO_2$ nanoparticles need to be considered. In this paper, Drude model and Maier's effective volume method are used to analyze the variation of the metal nanoparticle radius, separation between metal nanoparticle and dielectric molecule, and total absorption cross-section with original radiative efficiency on the photoluminescence property of Au-$TiO_2$ nanoparticles. The results show that to obtain the optimized enhancement factor for photoluminescence process, the size of Au nanoparticle is about 13 - 20 nm, the separation between Au nanoparticle and $TiO_2$ molecule is about 5 -15 nm, the total absorption cross-section of $TiO_2$ molecules is about $1-100nm^2$ and the original radiative efficiency of $TiO_2$ molecule is weak about 0.001- 0.1. With these fabrication parameters, the photoluminescence property of Au-$TiO_2$ nanoparticles can be enhanced several thousand times compared to traditional $TiO_2$ nanoparticles.

Toxicoproteomic identification of $TiO_2$ nanoparticle-induced protein expression changes in mouse brain

  • Jeon, Yu-Mi;Park, Seul-Ki;Lee, Mi-Young
    • Animal cells and systems
    • /
    • v.15 no.2
    • /
    • pp.107-114
    • /
    • 2011
  • A proteomic analysis of the proteins in mouse brain that were differentially expressed in response to $TiO_2$ nanoparticles was conducted to better understand the molecular mechanism of $TiO_2$ nanoparticle-induced brain toxicity at the protein level. A total of 990 proteins from mouse brain were resolved by two-dimensional gel electrophoresis. A comparative proteomic analysis revealed that the expression levels of 11 proteins were changed by more than 2-fold in response to $TiO_2$ nanoparticles: eight proteins were upregulated and three were downregulated by $TiO_2$ nanoparticles. In addition, the activities of several antioxidative enzymes and acetylcholine esterase were reduced in $TiO_2$ nanoparticle-exposed mouse brain. The protein profile alterations seem to be due to an indirect effect of $TiO_2$ nanoparticles, because $TiO_2$ nanoparticles were not detected in the brain in this investigation.

Synthesis and Characterization of Fe Doped TiO2 Nanoparticles by a Sol-Gel and Hydrothermal Process

  • Kim, Hyun-Ju;Jeong, Kwang-Jin;Bae, Dong-Sik
    • Korean Journal of Materials Research
    • /
    • v.22 no.5
    • /
    • pp.249-252
    • /
    • 2012
  • Fe doped $TiO_2$ nanoparticles were prepared under high temperature and pressure conditions by mixture of metal nitrate solution and $TiO_2$ sol. Fe doped $TiO_2$ particles were reacted in the temperature range of 170 to $200^{\circ}C$ for 6 h. The microstructure and phase of the synthesized Fe doped $TiO_2$ nanoparticles were studied by SEM (FE-SEM), TEM, and XRD. Thermal properties of the synthesized Fe doped $TiO_2$ nanoparticles were studied by TG-DTA analysis. TEM and X-ray diffraction pattern shows that the synthesized Fe doped $TiO_2$ nanoparticles were crystalline. The average size and distribution of the synthesized Fe doped $TiO_2$ nanoparticles were about 10 nm and narrow, respectively. The average size of the synthesized Fe doped $TiO_2$ nanoparticles increased as the reaction temperature increased. The overall reduction in weight of Fe doped $TiO_2$ nanoparticles was about 16% up to ${\sim}700^{\circ}C$; water of crystallization was dehydrated at $271^{\circ}C$. The transition of Fe doped $TiO_2$ nanoparticle phase from anatase to rutile occurred at almost $561^{\circ}C$. The amount of rutile phase of the synthesized Fe doped $TiO_2$ nanoparticles increased with decreasing Fe concentration. The effects of synthesis parameters, such as the concentration of the starting solution and the reaction temperature, are discussed.

Photocatalytic Properties of the Ag-Doped TiO2 Prepared by Sol-Gel Process/Photodeposition (졸-겔공정/광증착법을 이용한 Ag-Doped TiO2 합성 및 광촉매 특성)

  • Kim, Byeong-Min;Kim, Jung-Sik
    • Korean Journal of Materials Research
    • /
    • v.26 no.2
    • /
    • pp.73-78
    • /
    • 2016
  • $TiO_2$ nanoparticles were synthesized by a sol-gel process using titanium tetra isopropoxide as a precursor at room temperature. Ag-doped $TiO_2$ nanoparticles were prepared by photoreduction of $AgNO_3$ on $TiO_2$ under UV light irradiation and calcinated at $400^{\circ}C$. Ag-doped $TiO_2$ nanoparticles were characterized for their structural and morphological properties by X-ray diffractometry (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and transmission electron microscopy (TEM). The photocatalytic properties of the $TiO_2$ and Ag-doped $TiO_2$ nanoparticles were evaluated according to the degree of photocatalytic degradation of gaseous benzene under UV and visible light irradiation. To estimate the rate of photolysis under UV (${\lambda}=365nm$) and visible (${\lambda}{\geq}410nm$) light, the residual concentration of benzene was monitored by gas chromatography (GC). Both undoped/doped nanoparticles showed about 80 % of photolysis of benzene under UV light. However, under visible light irradiation Ag-doped $TiO_2$ nanoparticles exhibited a photocatalytic reaction toward the photodegradation of benzene more efficient than that of bare $TiO_2$. The enhanced photocatalytic reaction of Ag-doped $TiO_2$ nanoparticles is attributed to the decrease in the activation energy and to the existence of Ag in the $TiO_2$ host lattice, which increases the absorption capacity in the visible region by acting as an electron trapper and promotes charge separation of the photoinduced electrons ($e^-$) and holes ($h^+$). The use of Ag-doped $TiO_2$ nanoparticles preserved the option of an environmentally benign photocatalytic reaction using visible light; These particles can be applicable to environmental cleaning applications.

The Effect of Crystallinity on the Photoluminescence of TiO2 Nanoparticles (결정성에 따른 TiO2 나노입자의 포토루미네선스 영향)

  • Han, Wooje;Park, Hyung-Ho
    • Journal of the Microelectronics and Packaging Society
    • /
    • v.26 no.1
    • /
    • pp.23-28
    • /
    • 2019
  • The Titanium oxide ($TiO_2$) is an attractive ceramic material which shows non-toxic, high refractive index, catalytic activity and biocompatibility, and can be fabricated at a low cost due to its high chemical stability and large anisotropy. $TiO_2$ nanoparticles have been prepared by sol-gel method. The pH of solution can affect the $TiO_2$ crystallinity during the formation of nanoparticles. The prepared nanoparticles were characterized using Fourier transform infrared spectroscopy, scanning electron microscopy, X-ray diffraction, photoluminescence spectroscopy in order to investigate their structural and photoluminescence properties. Through these analysis, the size of $TiO_2$ nanoparticles were found to be smaller than 5 nm. As the crystallinity of the nanoparticles increased, the emission of PL in the 550 nm region increased. Therefore, luminescence characteristics can be improved by controlling the crystallinity of the $TiO_2$ nanoparticles.

Effect of Oxygen-Enriched Flame Temperature on the Crystalline Structures of the Flame-Synthesized TiO2 Nanoparticles (산소부화를 통한 화염온도 변화에 따른 연소합성된 TiO2 나노입자의 결정구조 변화)

  • Lee Gyo-Woo
    • Transactions of the Korean Society of Mechanical Engineers B
    • /
    • v.30 no.7
    • /
    • pp.692-699
    • /
    • 2006
  • In this work, $TiO_2$ nanoparticles were synthesized using $N_2-diluted$ and Oxygen-enriched co-flow hydrogen diffusion flames. The effect of flame temperature on the crystalline structure of the formed $TiO_2$ nanoparticles was investigated. The measured maximum centerline temperature of the flame ranged from 2,103k for oxygen-enriched flame to 1,339K for $N_2-diluted$ flame. The visible flame length and the height of the main reaction zone were characterized by direct photographs. The crystalline structures of $TiO_2$ nanoparticles were analyzed by XRD. From the XRD analysis, it was evident that the crystalline structures of the formed nanoparticles were divided into two sorts. In the higher temperature region, over the 1,700K, the fraction of formed $TiO_2$ nanoparticles having anatase-phase crystalline structure increased with increasing the flame temperature. On the contrary, in the lower temperature region, below the 1,600K, the fraction of anatase-phase nanoparticles increased with decreasing the flame temperature.

Titanium Dioxide Sol-gel Schottky Diodes and Effect of Titanium Dioxide Nanoparticle

  • Maniruzzaman, Mohammad;Zhai, Lindong;Mun, Seongcheol;Kim, Jaehwan
    • Journal of Electrical Engineering and Technology
    • /
    • v.10 no.6
    • /
    • pp.2343-2347
    • /
    • 2015
  • This paper reports the effect of Titanium dioxide (TiO2) nanoparticles on a TiO2 sol-gel Schottky diode. TiO2 nanoparticles were blended with TiO2 sol-gel to fabricate the Schottky diode. TiO2 nanoparticles showed strong anatase and rutile X-ray diffraction peaks. However, the mixture of TiO2 sol-gel and TiO2 nanoparticles exhibited no anatase and rutile peaks. The forward current of the Schottky diode drastically increased as the concentration of TiO2 nanoparticles increased up to 10 wt. % and decreased after that. The possible conduction mechanism is more likely space charge limited conduction.

Use of Core-Crosslinked Amphiphilic Polymer Nanoparticles as Templates for Synthesis of Nanostructured Inorganic Materials (코아 가교 양친성 고분자 나노입자 템플레이트를 이용한 무기물 나노 구조체 합성)

  • Kim, Hyun-Ji;Kim, Na-Hae;Kim, Juyoung
    • Journal of Adhesion and Interface
    • /
    • v.16 no.1
    • /
    • pp.6-14
    • /
    • 2015
  • In this study, physically and chemically stable core-crosslinked amphiphilic polymer (CCAP) nanoparticles were prepared using amphiphilic reactive precursors via soap-free emulsion process. Obtained CCAP nanoparticles were used as templates for synthesis of nanostructured $TiO_2$ nanoparticles. First, CCAP nanoparticles dispersed aqueous solutions were mixed with titanium isopropoxide to prepare stable organic-inorganic hybrid sols, and then obtained sols were spin coated onto glass substrate to prepare hybrid thin films onto glass, and then hybrid thin films were calcinated at various temperature to remove CCAP. Nanostructure of calcinated thin fims were examined by SEM. To study effect of CCAP nanoparticles on nanostructure of $TiO_2$ nanoparticles, the morphology of $TiO_2$ nanoparticles prepared using various CCAP templates was compared with that of $TiO_2$ nanoparticles prepared using conventional organic template, nonionic surfactant, Triton X-100.