scholarly journals Comparative study on antimicrobial activities of green synthesized TiO2 nanoparticles of Tephrosia purpurea leaves with its crude extracts

2020 ◽  
Vol 9 (2) ◽  
pp. 1022-1028
Keyword(s):  
Tio2 Nanoparticles ◽  
Spherical Surface ◽  
Anatase Phase ◽  
Sol Gel ◽  
Average Crystallite Size ◽  
Antimicrobial Activities ◽  
Wound Infections ◽  
Antimicrobial Potential ◽  
Tephrosia Purpurea ◽  
Crude Extracts

The present study deals with the enhancement of antimicrobial potential of Tephrosia purpurea crude extracts by making their composite with TiO2 nanoparticles against ubiquitous pathogens which may cause skin and wound infections. The synthesis was accomplished by the sol-gel method using precursor Titanium isopropoxide. The nanoparticles characterized by XRD, FESEM and FTIR techniques. XRD results showed that particles were in anatase phase with average crystallite size 12- 24 nm. FESEM reveals the spherical surface morphology of the nanoparticles. FTIR spectra gave the idea about associated functional groups with the synthesized particles. The antimicrobial potential of chemically synthesized TiO2 nanoparticles, green synthesized TiO2 nanoparticles and the crude extracts tested against Escherichia coli MTCC 40, Pseudomonas aeruginosa MTCC 2474 and Streptococcus pyogenes MTCC 442 which are actively involved in skin and wound infections. Results showed that green synthesized TiO2 nanoparticles gave better results in comparison with chemically synthesized TiO2 nanoparticles and crude extracts.

scholarly journals Influence of mild Cr3+ doping on the structural, optical, photochromic, and thermochromic reversibility of nano-titania systems

2019 ◽  
Vol 97 (4) ◽  
pp. 347-354 ◽  
Author(s):  
Rizwin Khanam ◽  
Dambarudhar Mohanta
Keyword(s):  
Band Gap ◽  
Anatase Phase ◽  
Sol Gel ◽  
Average Crystallite Size ◽  
Incident Radiation ◽  
Optical Absorption Spectroscopy ◽  
Smart Windows ◽  
Cell Parameters ◽  
Doped Titania ◽  
Reversible Thermochromism

We report on the effect of chromium doping on the band gap lowering of nano-titania (TiO2) and subsequent implications as regards coloration characteristics mediated via photochromism and thermochromism processes. As can be found in the X-ray diffractograms, the sol-gel derived, Cr3+-doped nano-TiO2 systems have exhibited an anatase phase with the evidence of peak shifting towards a lower diffraction angle. The average crystallite size decreases, whereas lattice unit cell parameters and, consequently, cell volume, tend to increase with the inclusion of Cr3+ into the titania host. To be specific, 1% Cr-doped titania system showed nearly 5.8% cell expansion as compared to its un-doped counterpart. As revealed from the optical absorption spectroscopy, a narrowing of band gap is observed for the Cr doped nano-titania system: 3.18 eV for the un-doped system, and 2.61 and 2.41 eV for 0.3% and 1% Cr doping cases, respectively, considering direct band-to-band transitions. Moreover, doping led noticeable lowering of the exponent (n value), from its normal value, which suggests inclusion of adequate non-parabolicity feature to the energy band scheme. The photochromic feature, for a given incident radiation, demonstrates a lowered transmission response with increasing Cr content. A reversible thermochromism response has also been demonstrated for doped nano-titania systems subjected to heating with temperature varying between 0–55 °C. The Cr3+ doped nano-titania and similar systems would find scope in smart windows, display components, photocatalysis, etc., when a select coloration is desired.

Structural and Optical Characterization of Synthesized TiO2 Nanopowder Using Sol–Gel Technique

2016 ◽  
Vol 15 (01n02) ◽  
pp. 1650002 ◽  
Author(s):  
S. Lourduraj ◽  
R. Victor Williams
Keyword(s):  
Anatase Phase ◽  
Sol Gel ◽  
Visible Spectrum ◽  
Average Crystallite Size ◽  
Xrd Analysis ◽  
Force Microscopy ◽  
Morphological Studies ◽  
Atomic Force ◽  
Gel Technique

The nanocrystalline TiO2 powder was synthesized by sol–gel method. The XRD analysis reveals that TiO2 powder was highly crystalline (anatase phase) and nanostructured with tetragonal system. The average crystallite size after calcined at 673[Formula: see text]K is found to be 7.7[Formula: see text]nm. The surface morphological studies using scanning electron microscopy (SEM) exhibit that the formation of nanosized TiO2 particles with less densification nature. Atomic force microscopy (AFM) topography exhibits the uniform distribution of spherical-shaped particles. The energy dispersive X-ray spectroscopy (EDX) confirms the presence of Titanium and Oxygen in synthesized TiO2 nanopowder. The value of optical bandgap of TiO2 nanopowder calculated from UV-Visible spectrum is 3.45[Formula: see text]eV. The presence of TiO2 particles is confirmed from the dominant fourier transform infrared (FTIR) peaks at 621[Formula: see text]cm[Formula: see text] and 412[Formula: see text]cm[Formula: see text].

scholarly journals Controlled Synthesis and Microstructural Properties of Sol-Gel TiO2 Nanoparticles for Photocatalytic Cement Composites

Nanomaterials ◽  
2018 ◽  
Vol 9 (1) ◽  
pp. 26 ◽  
Author(s):  
Elena Cerro-Prada ◽  
Sara García-Salgado ◽  
M.Angeles Quijano ◽  
Fernando Varela
Keyword(s):  
Particle Size ◽  
Phase Transformation ◽  
Tio2 Nanoparticles ◽  
Anatase Phase ◽  
Sol Gel ◽  
Titanium Isopropoxide ◽  
Titania Nanoparticles ◽  
Structural Defects ◽  
Microstructural Properties ◽  
Anatase Nanoparticles

Titania nanoparticles are intensely studied for photodegradation applications. Control of nanoscale morphology and microstructural properties of these materials is critical for photocatalytic performance. Uniform anatase-type TiO2 nanoparticles were prepared by the sol-gel process using titanium isopropoxide as precursor. Controlled annealing up to 400 ℃ established crystallization and particle size ranging between 20 and 30 nm. Detailed thermal examination reveals that anatase phase transformation into rutile is affected by the annealing temperature and by the initial particle size. The anatase to rutile phase transformation occurs in the nanoparticles at 550 ℃. The Total Reflection X-ray Fluorescence (TXRF) study of the anatase nanoparticles shows a shift towards higher energy in the Ka Ti line of 10 eV, related to structural defects. These features were discussed in the photocatalytic behavior of several cement-based materials modified with the so-prepared anatase nanoparticles. The photocatalytic activity of the anatase-type TiO2/cement mortar system is evaluated from the degradation of Methylene Blue (MB) under UV irradiation, monitored through the absorbance at 665 nm. The results show that the photocatalytic composites exhibit up to 76.6% degradation efficiency. Mechanical testing of the nano-TiO2 modified cementitious composites evinces a moderate reinforcement of the strength properties at long ages.

scholarly journals Study on the Photocatalytic and Antibacterial Properties of TiO2 Nanoparticles-Coated Cotton Fabrics

Materials ◽  
2019 ◽  
Vol 12 (12) ◽  
pp. 2010 ◽  
Author(s):  
Guangyu Zhang ◽  
Dao Wang ◽  
Jiawei Yan ◽  
Yao Xiao ◽  
Wenyan Gu ◽  
...  
Keyword(s):  
Tio2 Nanoparticles ◽  
Cotton Fabric ◽  
Sol Gel ◽  
Antibacterial Properties ◽  
Average Crystallite Size ◽  
Cotton Fabrics ◽  
Tetrabutyl Titanate ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Scanning Electron Microcopy

Herein, the amino-capped TiO2 nanoparticles were synthesized using tetrabutyl titanate and amino polymers by a two-step sol-gel and hydrothermal method technique for the fabrication of functional cotton fabric. The prepared TiO2 nanoparticles and the treated cotton fabric were characterized by transmission electron microscope (TEM), X-ray diffraction (XRD), field emission scanning electron microcopy (FE-SEM) photocatalytic and antibacterial measurement. The results indicate the typical characteristic anatase form of the amino-capped TiO2 NPs with an average crystallite size of 14.9 nm. The treated cotton fabrics exhibit excellent antibacterial property and good photocatalytic degradation of methylene blue.

scholarly journals Co/TiO2 nanoparticles: preparation, characterization and its application for photocatalytic degradation of methylene blue

2018 ◽  
Author(s):  
azadeh ebrahimian pirbazari ◽  
Pejman Monazzam ◽  
Behnam Fakhari Kisomi
Keyword(s):  
Methylene Blue ◽  
Photocatalytic Activity ◽  
Tio2 Nanoparticles ◽  
Anatase Phase ◽  
Sol Gel ◽  
Pure Tio2 ◽  
Cobalt Doping ◽  
X Ray Diffraction ◽  
X Ray ◽  
Ft Ir

In this work, TiO2 nanoparticles containing different amounts of cobalt were synthesized by sol-gel method using titanium (IV) isopropoxide and cobalt chloride as titanium and cobalt precursors, respectively. X-ray diffraction (XRD) results showed prepared samples include 100% anatase phase. The presence of cobalt in TiO2 nanoparticle network was established by XRD, scanning electron microscopy equipped with energy dispersive X-ray microanalysis (SEM-EDX), Fourier transform infrared (FT-IR) and N2 physisorption techniques. The increase of cobalt doping enhanced redshif in the diffuse reflectance spectra. The photocatalytic activity of the prepared samples was tested for degradation of methylene blue (MB) as a model of dye. Although the photocatalytic activity of pure TiO2 was found to be higher than that of Co/TiO2 samples under UV irradiation, the presence of 0.24% cobalt dopant in TiO2 nanoparticles resulted in a photocatalyst with the highest activity under visible light

Structure and Morphology of Sol-Gel Nanocrystalline TiO2 Films Coated on Glass Substrates

2010 ◽  
Vol 434-435 ◽  
pp. 565-567
Author(s):  
G.J. Ji ◽  
Zhi Ming Shi ◽  
G. Zhao
Keyword(s):  
Anatase Phase ◽  
Sol Gel ◽  
Average Crystallite Size ◽  
Rutile Phase ◽  
Dip Coating ◽  
Tio2 Films ◽  
Nanocrystalline Tio2 ◽  
Doped Tio2 ◽  
Glass Substrates ◽  
Dip Coating Technique

The Ce3+-doped and undoped nanocrystalline TiO2 films were prepared on glass substrates surface by sol-gel dip coating technique. The crystal structure and surface morphology of TiO2 films were characterized by means of X-ray diffractometer (XRD), transmission electron microscopy (TEM) and atomic force microscope (AFM). The results indicated that the Ce3+-doped TiO2 films were solely composed of the anatase phase whereas in the undoped films small amount of the rutile phase of TiO2 were present. The average crystallite size of the undoped TiO2 films was about 30nm and was decreased with Ce3+-doping in the TiO2 films. Moreover, the grains distributed more uniform and the surface roughness was smaller in the Ce3+-doped TiO2 films than in the undoped one. The action mechanism of Ce3+-doping inhibits the crystallization of the rutile phase and decreases the anatase granularity of TiO2 films is associated with its physicochemical properties, as well as ionic diffusion and valance change of Ce3+ to Ce4+ in the sintering process.

scholarly journals Compacting and densification of TiO2 nanoparticles

2017 ◽  
Vol 11 (2) ◽  
pp. 93-99 ◽  
Author(s):  
Roca Alvarez ◽  
Edson Leite ◽  
Elson Longo
Keyword(s):  
Activation Energy ◽  
Compressive Strength ◽  
Tio2 Nanoparticles ◽  
Sol Gel ◽  
Average Crystallite Size ◽  
Grain Boundary Sliding ◽  
Anatase Tio2 ◽  
Densification Process ◽  
Sol Gel Process ◽  
Boundary Sliding

This work investigated the compacting and densification behaviour of TiO2 nanoparticles prepared by the simple non-aqueous sol-gel process. The synthesized nanopowder has anatase TiO2 structure with the average crystallite size of 10 nm and agglomerated particles. The compressibility curve shows two well-defined linear parts that intersect at ~380MPa which is a measure of agglomerate compressive strength. The densification process was investigated by the dilatometric analysis using non-isothermal experiments. The apparent activation energy for the densification was calculated (88-102 kJ/mol). Grain rearrangement by grain boundary sliding was proposed as the dominant shrinkage mechanism.

On the Sol-gel Synthesis and Characterization of Titanium Oxide Nanoparticles

2011 ◽  
Vol 1352 ◽  
Author(s):  
Varun Chaudhary ◽  
Amit K. Srivastava ◽  
Jitendra Kumar
Keyword(s):  
Band Gap ◽  
Crystallite Size ◽  
Anatase Phase ◽  
Sol Gel ◽  
Finite Size ◽  
Average Crystallite Size ◽  
Photo Luminescence ◽  
Titanium Isopropoxide ◽  
Rutile Phase ◽  
Excitation Wavelength

ABSTRACTTiO2 nanoparticles have been prepared by sol-gel process using titanium isopropoxide as a precursor with ethanol and water as solvents. The synthesis involves gel formation, digestion for 24h, drying at 100oC for 10h, and calcination in air at 500-800oC for 2h. The resulting powder has been studied with respect to phase(s), morphology, optical absorption and photo -luminescence (PL) behaviour. The calcination of dried sol-gel product at 500oC for 2h leads to formation of anatase phase that possesses a tetragonal structure (a = 3.785 Å, c = 9.514 Å, Z = 4), average crystallite size ~ 11 nm and band gap of 3.34 eV. Further, increasing the time (t) of calcination causes crystallite growth that follows the relation d = α – β exp (-t/τ), α = 18.1 nm, β = 9.6 nm and τ = 6.9h. However, calcination of sol-gel product at 800oC for 2h gives rise to a rutile phase (tetragonal a = 4.593Å, c = 2.959Å, Z = 2), average crystallite size ~ 25 nm and band gap of 3.02 eV. The anatase phase exhibits strong PL emission peaks (excitation wavelength 405 nm) at 2.06 and 1.99 eV due to defect levels within the energy band gap. This observation has been attributed to finite size effects occurring in nanoparticles.

scholarly journals An Amalgam of Mg-Doped TiO2 Nanoparticles Prepared by Sol-Gel Method for Effective Antimicrobial and Photocatalytic Activity

2021 ◽  
Author(s):  
N NITHYA ◽  
S Gopi ◽  
G Bhoopathi
Keyword(s):  
Crystallite Size ◽  
Anatase Phase ◽  
Sol Gel ◽  
Average Crystallite Size ◽  
Gram Positive ◽  
Tem Analysis ◽  
Gram Negative ◽  
Gel Method ◽  
Sol Gel Method ◽  
And Shifts

Abstract In this study, undoped and Magnesium doped TiO2 nanoparticles (Mg-TiO2 NPs) were successfully synthesized via a simple sol-gel method cost-effectively. The prepared Mg- TiO2 NPs were characterized by UV-Vis, FTIR, PL, XRD, FESEM, TEM, and EDAX. UV – Visible Spectroscopy showed that an increase in the optical bandgap concerning the concentration of dopant Mg increases. The bandgap values were found to be 3.57-3.54 eV. FTIR spectra showed that the presence of the characteristic stretching and bending vibrational band of Ti – O bonding at 468 cm-1 and shifts in vibrational bands were observed for Mg-TiO2 NPs. PL spectra of Mg- TiO2 NPs at different concentrations exhibit a strong UV emission band. X-ray diffraction confirmed the formation of the tetragonal anatase phase. The average crystallite size of prepared samples was found to be 22-19 nm. The average crystallite size of Mg- TiO2 NPs decreases with increasing the concentration of dopant Mg. The FESEM and TEM analysis confirmed that the spherical morphology for both TiO2 and Mg-TiO2 NPs. SAED pattern confirms the crystalline nature of prepared samples. EDAX spectra confirm the presence of Ti, O, and Mg and confirm that Mg2+ ions are present in the TiO2 lattices. The prepared samples were investigated against gram-positive (B. subtilis and S. aureus) and gram-negative (P. eugenia and K. Pneumonia) bacteria. The prepared samples showed potent antibacterial activity against gram-negative bacteria than the gram-positive bacteria. The prepared samples show the excellent photocatalytic degradation for Methylene blue.

Cu Doped TiO2: Visible Light Assisted Photocatalytic Antimicrobial Activity and High Temperature Anatase Stability

2018 ◽  
Author(s):  
Snehamol Mathew ◽  
Priyanka Ganguly ◽  
Stephen Rhatigan ◽  
Vignesh Kumaravel ◽  
Ciara Byrne ◽  
...  
Keyword(s):  
Visible Light ◽  
Visible Light Irradiation ◽  
Density Functional ◽  
Anatase Phase ◽  
Sol Gel ◽  
Chemical Properties ◽  
Light Irradiation ◽  
Health Concern ◽  
Bacterial Inactivation ◽  
X Ray

Indoor surface contamination by microbes is a major public health concern. A damp environment is one potential sources for microbe proliferation. Smart photocatalytic coatings on building surfaces using semiconductors like titania (TiO<sub>2</sub>) can effectively curb this growing threat.<b> </b>Metal-doped titania in anatase phase has been proved as a promising candidate for energy and environmental applications. In this present work, the antimicrobial efficacy of copper (Cu) doped TiO<sub>2 </sub>(Cu-TiO<sub>2</sub>) was evaluated against <i>Escherichia coli</i> (Gram-negative) and <i>Staphylococcus aureus</i> (Gram-positive) under visible light irradiation. Doping of a minute fraction of Cu (0.5 mol %) in TiO<sub>2 </sub>was carried out <i>via</i> sol-gel technique. Cu-TiO<sub>2</sub> further calcined at various temperatures (in the range of 500 °C – 700 °C) to evaluate the thermal stability of TiO<sub>2</sub> anatase phase. The physico-chemical properties of the samples were characterised through X-ray diffraction (XRD), Raman spectroscopy, X-ray photo-electron spectroscopy (XPS) and UV-visible spectroscopy techniques. XRD results revealed that the anatase phase of TiO<sub>2</sub> was maintained well, up to 650 °C, by the Cu dopant. UV-DRS results suggested that the visible light absorption property of Cu-TiO<sub>2 </sub>was enhanced and the band gap is reduced to 2.8 eV. Density functional theory (DFT) studies emphasises the introduction of Cu<sup>+</sup> and Cu<sup>2+</sup> ions by replacing Ti<sup>4+</sup> ions in the TiO<sub>2</sub> lattice, creating oxygen vacancies. These further promoted the photocatalytic efficiency. A significantly high bacterial inactivation (99.9%) was attained in 30 mins of visible light irradiation by Cu-TiO<sub>2</sub>.

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