TiO2-Carbon Nanotube Nanocomposite Particles (original) (raw)
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Synthesis and Photocatalytic Activity of Anatase TiO2 Nanoparticles-coated Carbon Nanotubes
Nanoscale Research Letters, 2010
A simple and straightforward approach to prepare TiO 2-coated carbon nanotubes (CNTs) is presented. Anatase TiO 2 nanoparticles (NPs) with the average size *8 nm were coated on CNTs from peroxo titanic acid (PTA) precursor even at low temperature of 100°C. We demonstrate the effects of CNTs/TiO 2 molar ratio on the adsorption capability and photocatalytic efficiency under UV-visible irradiation. The samples showed not only good optical absorption in visible range, but also great adsorption capacity for methyl orange (MO) dye molecules. These properties facilitated the great enhancement of photocatalytic activity of TiO 2 NPs-coated CNTs photocatalysts. The TiO 2 NPs-coated CNTs exhibited 2.45 times higher photocatalytic activity for MO degradation than that of pure TiO 2 .
2015
ABSTRAK ii ACKNOWLEDGEMENTS iii APPROVAL iv DECLARATION vi LIST OF TABLES x LIST OF FIGURES xi LIST OF SYMBOLS xiii LIST OF ABBREVIATIONS xiv CHAPTER 1 NANOMATERIAL AND NANOTECHNOLOGY 1.1 Introduction 1.2 Problem Statement 1.3 Research Objectives 1.4 Scope of the research 1.5 Significance of the research 1.6 Thesis outline 2 LITERATURE REVIEW 2.1 Introduction 2.2 Titanium dioxide (TiO2) 2.3 Carbon nanotube 2.4 Deposition of TiO2 on CNTs surface 2.5 Characterization of CNTs/TiO2 nanocomposite 2.6 Photocatalytic activity of CNT/TiO2 nanocomposites 2.6.1 Light intensity 2.6.2 pH of the solution 2.6.3 Reaction temperature 2.6.4 Photocatalyst concentration 2.6.5 Concentration of the pollutant 3 THEORY 3.1
Photocatalytic Carbon‐Nanotube–TiO2 Composites
2009
Abstract The literature and advances in photocatalysis based on the combination of titania (TiO 2) and carbon nanotubes is presented. The semiconductor basis for photocatalysis is introduced for anatase and rutile. Furthermore, the proposed mechanisms of catalytic enhancement resulting from the pairing of the titania semiconductor with either metallic, semiconducting, or defect-rich carbon nanotubes (CNT) is discussed. Differences are apparent for the mixtures and chemically bonded CNT–TiO 2 composites.
Synthesis and characterization of carbon nanotubes–TiO 2 nanocomposites
Carbon, 2004
The main objective of this paper is to coat carbon multiwall nanotubes surface with TiO 2 as anatase in view of photocatalytic application for these nanocomposites. Carbon nanotubes were produced by catalytic decomposition of acetylene at 600°C. The coating was performed by a sol-gel method using classical alkoxides as Ti(OEt) 4 and Ti(OPr i ) 4 and by hydrothermal hydrolysis of TiOSO 4 , leading to different TiO 2 morphologies. In using the sol-gel method, nanotubes are coated either with a continuous TiO 2 thin film when the precursor is Ti(OEt) 4 , or with TiO 2 nanoparticles when the precursor is Ti(OPr i ) 4 . By hydrothermal treament, more compact and crystalline nanocomposites are obtained.
1 D TiO 2 nanomaterials (nanotubes, nanowires) were synthesized through hydrothermal treatment of TiO 2 powder (P25) in concentrated alkaline solutions (NaOH for nanotubes, KOH for nanowires) followed by calcination at varying temperatures between 400°C and 700°C. Samples were characterized by HRTEM, XRD, Raman spectroscopy, and N 2 adsorption-desorption isotherms. High surface area nanotubular TiO 2 materials can maintain their 1D morphology up to a temperature of calcination of 400°C while changing their phase from hydrogenotitanate to anatase. The use of KOH leads to a retarded formation of anatase. Photocatalytic results showed that TiO 2 anatase nanotubes calcined at 400°C can degrade formic acid with a rate constant four times higher than for P25. A direct correlation between surface area and photocatalytic activity explains the much higher activity of TiO 2 anatase nanotubes. On the opposite, for the degradation of phenol, P25 remains more active. In the disinfection of water...
Fabrication of carbon-modified TiO2 nanotube arrays and their photocatalytic activity
Materials Letters, 2008
TiO 2 nanotube (TN) arrays were fabricated by an anodic oxidation process. Through a heat treatment of the as-fabricated TN arrays under a continuous Ar and acetylene flux, carbon-modified TN (C-TN) arrays were obtained. The as-fabricated catalysts were characterized by FE-SEM, HRTEM, XPS, Raman and UV-Vis spectra. Moreover, photocatalytic activity of the C-TN arrays was evaluated through the photodegradation of aqueous methyl blue. The experiments demonstrated that the C-TN arrays display an excellent photocatalytic activity. Under sunlight irradiation, the C-TN arrays are able to almost completely decompose the methylene blue pollutant of 1 × 10 − 5 M within 300 min.
The Journal of Physical Chemistry C, 2010
A carbon nanotubes (CNT)/TiO 2 nanocomposite photocatalyst has been prepared by a simple impregnation method, which is used, for the first time, for gas-phase degradation of benzene. It is found that the asprepared CNT/TiO 2 nanocomposite exhibits an enhanced photocatalytic activity for benzene degradation, as compared with that over commerical titania (Degussa P25). A similar phenomenon has also been found for liquid-phase degradation of methyl orange. The characterization of photocatalysts by a series of joint techniques, including X-ray diffraction, transmission electron microscopy, ultraviolet/visible (UV/vis) diffuse reflectance spectra, and photoluminescence spectra, discloses that CNT has two kinds of crucial roles in enhancement of photocatalytic activity of TiO 2. One is to act as an electron reservoir, which helps to trap electrons emitted from TiO 2 particles due to irradiation by UV light, therefore hindering electron-hole pairs recombination. The other is to act as a dispersing template or support to control the morphology of TiO 2 particles in the CNT/TiO 2 nanocomposite, and this important role was neglected in previous studies. Accordingly, a reasonable model is proposed to expain the role of CNT in CNT/TiO 2 composites as a photocatalyst for degradation of organic pollutants.
Journal of Sol-Gel Science and Technology, 2017
Multiwall carbon nanotubes were coupled with titanium dioxide (in different mole ratios of titanium and carbon) at the nano-scale, using a simple sonochemical and calcination process. The titanium dioxide-multiwall carbon nanotubes nanocomposites were for the first time surface modified with an innovative biotechnology-based reaction by using laccase to activate and covalently graft gallic acid dimers/oligomers/polymers on the nanocomposite surface in order to impart new functionalities and to minimize the nanocomposites' toxicity. Structure of the titanium dioxidemultiwall carbon nanotubes, before and after surface modification, was investigated with X-ray powder diffraction, infrared, and UV-visible diffuse reflectance spectroscopy analysis, and scanning electron microscopy. The results indicated preferential formation of anatase titanium dioxide on one hand and covalent grafting of gallic acid dimers/ oligomers/polymers functionalities on the nanocomposite surface, on the other. After modification, the antioxidant activity was analyzed using 2,2-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) and photocatalytic activity toward the liquid-phase degradation of methylene blue in aqueous solution under both UV and visible light irradiation. Up to 98% antioxidant activity of the surface modified nanocomposites was established after 24 h of incubation, whereas non-modified nanocomposite induced the formation of the ABTS •+ radicals. In addition, 1.3-2.8-fold reduction in photocatalytic activity was achieved, depending on the irradiation. Accordingly, the gallic acid dimers/oligomers/polymers modified titanium dioxidemultiwall carbon nanotubes appear to simultaneously exhibit photocatalytic activity with an ability to scavenge free radicals, and can thus be considered as engineered nanoparticles with low toxicity.
Enhancement of photocatalytic activity of mesoporous TiO2 by using carbon nanotubes
Applied Catalysis A: General, 2005
Titanium dioxide/carbon nanotubes (TiO 2 /CNTs) composites were prepared with the aid of ultrasonic irradiation. Products of different TiO 2 :CNTs molar ratio were characterized by X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET) adsorption analysis, thermogravimetric and differential thermal analysis (TGA-DSC), photoluminescence (PL) and UV-vis spectroscopy measurements (UV-vis). The photocatalytic activity was evaluated by the degradation of acetone and by the detection of the hydroxyl radical (ÁOH) signals using electron paramagnetic resonance (EPR). It is found that the crystalline TiO 2 is composed of both anatase and brookite phases. The agglomerated morphology and the particle size of TiO 2 in the composites change in the presence of CNTs. The CNTs in the composites are virtually all covered by TiO 2. Other than an increase of the surface area, the addition of CNTs does not affect the mesoporous nature of the TiO 2. Meanwhile, more hydroxyl groups are available on the surface of the composite than in the case of the pure TiO 2. The higher the content of CNTs, there is more effective in the suppression of the recombination of photo-generated e À /h + pairs. However, excessive CNTs also shield the TiO 2 from absorbing UV light. The optimal amount of TiO 2 and CNTs is in the range of 1:0.1 and 1:0.2 (feedstock molar ratio). These samples have much more highly photocatalytic activity than P25 and TiO 2 /activated carbon (AC) composite. The mechanism for the enhanced photocatalytic activity of TiO 2 by CNTs is proposed.