• Title/Summary/Keyword: $TiO_2$ Nanotubes

Search Result 142, Processing Time 0.019 seconds

Photo-catalytic Properties of Nanotubes Synthesized using TiO2 Nanoparticles

  • Kim, Hyun;Kim, Dong Yun;Yang, Bee Lyong
    • Journal of the Korean Ceramic Society
    • /
    • v.55 no.3
    • /
    • pp.239-243
    • /
    • 2018
  • Up to now, microstructure changes of photocatalysts have been studied to improve photocatalytic activity. Especially, to improve the adsorption of reactants and reactive sites, porous and fine crystal structures have received much attention because of their large specific surface area. In this study, $TiO_2$ nanotubes were synthesized by hydrothermal method using $TiO_2$ nanoparticles; nanotubes were evaluated by oxidized methylene blue reduction test. Using synthesized $TiO_2$ nanotubes, results of TEM showed that the $TiO_2$ nanoparticles were changed into folding sheets and nanotubes. XRD results showed that the peaks of the nanoparticles almost disappeared and only the rutile (110) and anatase (200) peaks were observed. Comparison of photocatalytic properties of nanoparticles and nanotube structures was performed by measuring the UV-vis absorbance with reducing oxidized methylene blue. As a result, the reduction rate of nanotubes was found to be $0.24{\mu}mol/s$, which was 2.6 times higher than the rate of reduction of nanoparticles.

Effect of Curing Period on Photocatalytic Effect of TiO2 Nanotubes-reinforced Cement Paste (양생기간이 TiO2 나노튜브 보강 시멘트 페이스트의 광촉매 효과에 미치는 영향)

  • Liu, Jun-Xing;Jin, Da-hyung;Bae, Sung-chul
    • Proceedings of the Korean Institute of Building Construction Conference
    • /
    • 2021.11a
    • /
    • pp.172-173
    • /
    • 2021
  • With the development of nano-reinforcement technology and the increasing concern for environmental issues, TiO2 nanomaterials have received wide attention as an additive besides carbon nanomaterials that can be used to enhance the mechanical properties of cement-based materials. Also, TiO2-based materials can allow cement-baned materials with photocatalytic capability, providing a potentially effective approach to reduce environmental problems. In this work, compressive strength, splitting tensile strength, and degradation of methylene blue solution were used as target to assess the effect of TiO2 nanotubes on the mechanical strength and photocatalytic effect of hardened cement paste at different curing time. According to the strength results, the optimum amount of TiO2 was identified as 0.5% of the weight of cement. Meanwhile, the TiO2 nanotubes-reinforced specimen exhibited better photocatalytic effect in the early stage of curing.

  • PDF

RuO2-Doped TiO2 Nanotube Membranes Prepared via a Single-Step/Potential Shock Sequence

  • Yoo, Hyeonseok;Seong, Mijeong;Choi, Jinsub
    • Journal of Electrochemical Science and Technology
    • /
    • v.10 no.3
    • /
    • pp.271-275
    • /
    • 2019
  • Anodic $TiO_2$ nanotubes were simultaneously grown and doped with $RuO_2$ by single-step anodization in a negatively-charged $RuO_4{^-}$ precursor. Subsequently, a high positive voltage was imposed on the nanotubes in an $F^-$-based electrolyte (a process referred to as potential shock), which led to the formation of a through-hole $RuO_2$-doped $TiO_2$ nanotube membrane without significant loss of the $RuO_2$ catalyst. XPS results confirmed that the doped Ru metal was converted into $RuO_2$ as the potential shock voltage increased. Further increases in the potential shock voltage led to the formation of $RuO_x/Ru$ in the $TiO_2$ nanotubes. All of our results clearly showed that a through-hole catalyst-doped $TiO_2$ nanotube membrane can be produced by a sequence consisting of single-step anodization and the potential shock process.

Effect of calcination temperature on photocatalytic activities of Er-TiO2 nanotubes

  • Song, Yo-Seung;Lee, Myung-Hyun;Kim, Bae-Yeon;Lee, Deuk Yong
    • Journal of Ceramic Processing Research
    • /
    • v.20 no.2
    • /
    • pp.182-186
    • /
    • 2019
  • 0.7 mol% Er-TiO2 nanotubes were prepared using a sol-gel derived electrospinning and subsequent calcination at intervals of 50 ℃ from 500 ℃ to 650 ℃ to investigate the effect of calcination temperature on the crystal structure and the photocatalytic activity of methylene blue (MB). X-ray diffraction (XRD) results indicated that Er-TiO2 nanotubes calcined at 500 ℃ were composed of anatase only. However, mixed phases of anatase (51%, 55%, 96%) and rutile (49%, 45%, 4%) were observed for the nanotubes calcined at 550 ℃, 600 ℃ and 650 ℃, respectively. As the calcination temperature rose from 500 ℃ to 600 ℃, the Barrette-Emmett-Teller (BET) surface area and degradation kinetic constant increased from 97.77 ㎡/g to 117.62 ㎡/g and from 1.2 × 10-2min-1 to 1.6 × 10-2 min-1, respectively. The Er-TiO2 nanotubes calcined at 600 ℃ exhibited enhanced MB degradation (87%) compared to that of Er-TiO2 nanofibers (37%) due to the synergic combinations of tailored mixed crystals and larger BET area.

Effects of incorporation of 2.5 and 5 wt% TiO2 nanotubes on fracture toughness, flexural strength, and microhardness of denture base poly methyl methacrylate (PMMA)

  • Naji, Sahar Abdulrazzaq;Behroozibakhsh, Marjan;Kashi, Tahereh Sadat Jafarzadeh;Eslami, Hossein;Masaeli, Reza;Mahgoli, Hosseinali;Tahriri, Mohammadreza;Lahiji, Mehrsima Ghavvami;Rakhshan, Vahid
    • The Journal of Advanced Prosthodontics
    • /
    • v.10 no.2
    • /
    • pp.113-121
    • /
    • 2018
  • PURPOSE. The aim of this preliminary study was to investigate, for the first time, the effects of addition of titania nanotubes ($n-TiO_2$) to poly methyl methacrylate (PMMA) on mechanical properties of PMMA denture base. MATERIALS AND METHODS. $TiO_2$ nanotubes were prepared using alkaline hydrothermal process. Obtained nanotubes were assessed using FESEM-EDX, XRD, and FT-IR. For 3 experiments of this study (fracture toughness, three-point bending flexural strength, and Vickers microhardness), 135 specimens were prepared according to ISO 20795-1:2013 (n of each experiment=45). For each experiment, PMMA was mixed with 0% (control), 2.5 wt%, and 5 wt% nanotubes. From each $TiO_2$:PMMA ratio, 15 specimens were fabricated for each experiment. Effects of $n-TiO_2$ addition on 3 mechanical properties were assessed using Pearson, ANOVA, and Tukey tests. RESULTS. SEM images of $n-TiO_2$ exhibited the presence of elongated tubular structures. The XRD pattern of synthesized $n-TiO_2$ represented the anatase crystal phase of $TiO_2$. Moderate to very strong significant positive correlations were observed between the concentration of $n-TiO_2$ and each of the 3 physicomechanical properties of PMMA (Pearson's P value ${\leq}.001$, correlation coefficient ranging between 0.5 and 0.9). Flexural strength and hardness values of specimens modified with both 2.5 and 5 wt% $n-TiO_2$ were significantly higher than those of control ($P{\leq}.001$). Fracture toughness of samples reinforced with 5 wt% $n-TiO_2$ (but not those of 2.5% $n-TiO_2$) was higher than control (P=.002). CONCLUSION. Titania nanotubes were successfully introduced for the first time as a means of enhancing the hardness, flexural strength, and fracture toughness of denture base PMMA.

Template-directed Atomic Layer Deposition-grown $TiO_2$ Nanotubular Photoanode-based Dye-sensitized Solar Cells

  • Yu, Hyeon-Jun;Panda, Sovan Kumar;Kim, Hyeon-Cheol;Kim, Myeong-Jun;Yang, Yun-Jeong;Lee, Seon-Hui;Sin, Hyeon-Jeong
    • Proceedings of the Materials Research Society of Korea Conference
    • /
    • 2011.05a
    • /
    • pp.239.1-239.1
    • /
    • 2011
  • Dye sensitized solar cells (DSC) are promising devices for inexpensive, nontoxic, transparent, and large-scale solar energy conversion. Generally thick $TiO_2$ nanoporous films act as efficient photoanodes with their large surface area for absorbing light. However, electron transport through nanoparticle networks causes the slowdown and the loss of electron transport because of a number of interparticle boundaries inside the conduction path. We have studied DSCs with precisely dimension-controlled $TiO_2$ nanotubes array as photoanode. $TiO_2$ nanotubes array is prepared by template-directed fabrication method with atomic layer deposition. Well-ordered nanotubes array provides not only large surface area for light absorbing but also direct pathway for electrons with minimalized grain boundaries. Large enlongated anatase grains in the nanotubes could enhance the conductivity of electrons, but also suppress the recombination with holes through defect sites during diffusion into the electrode. To study the effect of grain boundaries, we fabricated two kinds of nanotubes which have different grain sizes by controlling deposition conditions. And we studied electron conduction through two kinds of nanotubes with different grain structures. The solar cell performance was studied as a function of thickness and grain structures. And overall solar-to-electric energy conversion efficiencies of up to 7% were obtained.

  • PDF

Highly ordered TiO2 nanotubes; Synthesis and applications (고도로 정렬된 TiO2 나노튜브의 제조와 활용)

  • Yoo, JeongEun;Lee, Kiyoung
    • Journal of the Korean institute of surface engineering
    • /
    • v.55 no.1
    • /
    • pp.1-8
    • /
    • 2022
  • Titanium dioxide (TiO2) is one of the most intensively investigated materials in materials science. Mostly, TiO2 has been used in the form of nanoparticles, but recently new highly ordered TiO2 nanotubes (U-tube) has been introduced and applied to various applications due to their one-dimensional charge path way. In the present paper, we described the formation process and physical properties of U-tube then, gave examples of applications in sequence. Firstly, in photocatalysis, U-tube was used with Au/Pt co-catalysts and showed enhanced photogenerated H2 efficiency compared to bare TiO2. Secondly, photoelectrochemical performance of U-tube was evaluated with different heat-treatment temperatures. As a further application, two different types of electrical cell (Ti-TiO2-Pt and Ti-TiO2-PtNP) was configurated to observe memristive behavior of U-tube. Both cells behaved as switching electrodes and follow a memristive movement in the high and low resistance state extremely well with high reproducibility.

Analyzing corrosion rates of TiO2 nanotubes/titanium separation passive layer under surface and crystallization changes

  • Torres, I. Zamudio;Dominguez, A. Sosa;Bueno, J.J. Perez;Meas, Y.;Lopez, M.L. Mendoza;Dector, A.
    • Advances in nano research
    • /
    • v.10 no.3
    • /
    • pp.211-219
    • /
    • 2021
  • The evaluation of the corrosion resistance of titanium with a TiO2 nanotubes top layer was carried out (TiO2 NT). These nanostructures were evolved into anatase nanoparticles without heat treatment in an aqueous medium, which is a novel phenomenon. This work analyzes the layer between the nanotube bottom and the substrate, which is thin and still susceptible to corrosion. The bottom of TiO2 nanotubes having Fluor resulting from the synthesis process changed between amorphous to crystalline anatase with a crystallite size of about 4 nm, which influenced the corrosion rates. Four kinds of samples were evaluated. A) NT by Ti anodizing; B) NTSB for Ti plates, either modifying its surface or anodizing the modified surface; C) NT-480 for anodized Ti and heat-treated (480℃) for reaching the anatase phase; D) NTSB-480 for Ti plates, first, modifying its surface using sandblast, after that, anodizing the modified surface, and finally, heat-treated to 480℃ to compare with samples having induced crystallization and passivation. Four electrochemical techniques were used to evaluate the corrosion rates. The surfaces having TiO2 nanotubes with a sandblast pre-treatment had the highest resistance to corrosion.

Doping a metal (Ag, Al, Mn, Ni and Zn) on TiO2 nanotubes and its effect on Rhodamine B photocatalytic oxidation

  • Gao, Xinghua;Zhou, Beihai;Yuan, Rongfang
    • Environmental Engineering Research
    • /
    • v.20 no.4
    • /
    • pp.329-335
    • /
    • 2015
  • The effects of ion-doping on $TiO_2$ nanotubes were investigated to obtain the optimal catalyst for the effective decomposition of Rhodamine B (RB) through UV photocatalytic oxidation process. Changing the calcination temperature, which changed the weight fractions of the anatase phase, the average crystallite sizes, the BET surface area, and the energy band gap of the catalyst, affected the photocatalytic activity of the catalyst. The ionic radius, valence state, and configuration of the dopant also affected the photocatalytic activity. The photocatalytic activities of the catalysts on RB removal increased when $Ag^+$, $Al^{3+}$ and $Zn^{2+}$ were doped into the $TiO_2$ nanotubes, whereas such activities decreased as a result of $Mn^{2+}$ or $Ni^{2+}$ doping. In the presence of $Zn^{2+}$-doped $TiO_2$ nanotubes calcined at $550^{\circ}C$, the removal efficiency of RB within 50 min was 98.7%.

Growth Behaviors of Anodic Titanium Oxide Nanotubes in the Ethylene Glycol Solution According to Water Contents (에틸렌 글리콜 용액에서 물 함량에 따른 티타늄 양극산화 나노튜브의 성장거동)

  • Lee, Byunggwan;Lee, Seongeun;Choi, Jinwook;Jeong, Yongsoo;Oh, Han-Jun;Lee, Oh Yeon;Chi, Choong-Soo
    • Korean Journal of Metals and Materials
    • /
    • v.46 no.11
    • /
    • pp.730-736
    • /
    • 2008
  • $TiO_2$ nanotubes fabricated in aqueous HF-based electrolytes have been generally grown only to about 500nm in length because of the strong dissolubility of HF acid. In this paper, ethylene glycol solution has been applied for increasing the length of the anodic $TiO_2$ nanotubes, and the growth behaviors of the nanotubes according to water contents has been investigated. Anodization of Ti in ethylene glycol + 1 wt% $NH_4F$ (EG solution) with water additions up to 10 wt% were carried out at the constant voltage of 20 V. The results show that a thin titanium oxide layer is formed in the initial stage and the nanotube structure grows underneath the initial layer. And the length of $TiO_2$ nanotubes decreases with the increasing water content in the solution. It can be ascribed to the locally acidified circumstance around the barrier layer inside the nanopore due to $H^+$ ion originated from water. The XPS for the nanotubes suggests that the spectra of Ti2p and O1s are the major chemical bonding states of the $TiO_2$, and those for F1s, N1s and C1s come from the compound of $(NH_4)_2TiF_6$.