scholarly journals Innovative Ag–TiO2 Nanofibers with Excellent Photocatalytic and Antibacterial Actions

Catalysts ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1234
Author(s):  
Petronela Pascariu ◽  
Corneliu Cojocaru ◽  
Anton Airinei ◽  
Niculae Olaru ◽  
Irina Rosca ◽  
...  
Keyword(s):  
Band Gap Energy ◽  
Morphological Characterization ◽  
Pure Tio2 ◽  
Electron Hole ◽  
Tio2 Nanofibers ◽  
One Dimensional ◽  
E Coli ◽  
Small Crystals ◽  
Tio2 Nanostructures ◽  
Hole Recombination

Ag–TiO2 nanostructures were prepared by electrospinning, followed by calcination at 400 °C, and their photocatalytic and antibacterial actions were studied. Morphological characterization revealed the presence of one-dimensional uniform Ag–TiO2 nanostructured nanofibers, with a diameter from 65 to 100 nm, depending on the Ag loading, composed of small crystals interconnected with each other. Structural characterization indicated that Ag was successfully integrated as small nanocrystals without affecting much of the TiO2 crystal lattice. Moreover, the presence of nano Ag was found to contribute to reducing the band gap energy, which enables the activation by the absorption of visible light, while, at the same time, it delays the electron–hole recombination. Tests of their photocatalytic activity in methylene blue, amaranth, Congo red and orange II degradation revealed an increase by more than 20% in color removal efficiency at an almost double rate for the case of 0.1% Ag–TiO2 nanofibers with respect to pure TiO2. Moreover, the minimum inhibitory concentration was found as low as 2.5 mg/mL for E. coli and 5 mg/mL against S. aureus for the 5% Ag–TiO2 nanofibers. In general, the Ag–TiO2 nanostructured nanofibers were found to exhibit excellent structure and physical properties and to be suitable for efficient photocatalytic and antibacterial uses. Therefore, these can be suitable for further integration in various important applications.

scholarly journals Graphene Oxide-Doped MgO Nanostructures for Highly Efficient Dye Degradation and Bactericidal Action

2021 ◽  
Vol 16 (1) ◽  
Author(s):  
M. Ikram ◽  
T. Inayat ◽  
A. Haider ◽  
A. Ul-Hamid ◽  
J. Haider ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Dye Degradation ◽  
Inhibition Zone ◽  
Chemical Precipitation ◽  
Band Gap Energy ◽  
Cubic Phase ◽  
Electron Hole ◽  
Fixed Amount ◽  
E Coli ◽  
Spectroscopy Optical

AbstractVarious concentrations (0.01, 0.03 and 0.05 wt ratios) of graphene oxide (GO) nanosheets were doped into magnesium oxide (MgO) nanostructures using chemical precipitation technique. The objective was to study the effect of GO dopant concentrations on the catalytic and antibacterial behavior of fixed amount of MgO. XRD technique revealed cubic phase of MgO, while its crystalline nature was confirmed through SAED profiles. Functional groups presence and Mg-O (443 cm−1) in fingerprint region was evident with FTIR spectroscopy. Optical properties were recorded via UV–visible spectroscopy with redshift pointing to a decrease in band gap energy from 5.0 to 4.8 eV upon doping. Electron–hole recombination behavior was examined through photoluminescence (PL) spectroscopy. Raman spectra exhibited D band (1338 cm−1) and G band (1598 cm−1) evident to GO doping. Formation of nanostructure with cubic and hexagon morphology was confirmed with TEM, whereas interlayer average d-spacing of 0.23 nm was assessed using HR-TEM. Dopants existence and evaluation of elemental constitution Mg, O were corroborated using EDS technique. Catalytic activity against methyl blue ciprofloxacin (MBCF) was significantly reduced (45%) for higher GO dopant concentration (0.05), whereas bactericidal activity of MgO against E. coli was improved significantly (4.85 mm inhibition zone) upon doping with higher concentration (0.05) of GO, owing to the formation of nanorods.

scholarly journals Synthesis of Heterostructure of ZnO@MOF-46(Zn) to Improve the Photocatalytic Performance in Methylene Blue Degradation

Crystals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1379
Author(s):  
Jiraporn Buasakun ◽  
Phakinee Srilaoong ◽  
Ramida Rattanakam ◽  
Tanwawan Duangthongyou
Keyword(s):  
Methylene Blue ◽  
Band Gap ◽  
Photocatalytic Performance ◽  
Degradation Process ◽  
Band Gap Energy ◽  
Photocatalytic Efficiency ◽  
Electron Hole ◽  
Methylene Blue Degradation ◽  
Gap Energy ◽  
Hole Recombination

The heterostructure of ZnO and MOF-46(Zn) was synthesized to improve the photocatalytic performance of ZnO and prove the synergistic theory that presented the coexistence of ZnO and MOF-46(Zn), providing better efficiency than pure ZnO. The heterostructure material was synthesized by using prepared ZnO as a Zn2+ source, which was reacted with 2-aminoterephthalic acid (2-ATP) as a ligand to cover the surface of ZnO with MOF-46(Zn). The ZnO reactant materials were modified by pyrolysis of various morphologies of IRMOF-3 (Zn-MOF) prepared by using CTAB as a morphology controller. The octahedral ZnO obtained at 150 mg of CTAB shows better efficiency for photodegradation, with 85.79% within 3 h and a band gap energy of 3.11 eV. It acts as a starting material for synthesis of ZnO@MOF-46(Zn). The ZnO/MOF-46(Zn) composite was further used as a photocatalyst material in the dye (methylene blue: MB) degradation process, and the performance was compared with that of pure prepared ZnO. The results show that the photocatalytic efficiency with 61.20% in the MB degradation of the heterostructure is higher than that of pure ZnO within 60 min (90.09% within 180 min). The reason for this result may be that the coexistence of ZnO and MOF-46(Zn) can absorb a larger range of energy and reduce the possibility of the electron–hole recombination process.

scholarly journals One dimensional efficient photocatalyst based on plasmonic grating

2021 ◽  
Author(s):  
Yaser Alisa ◽  
S. M. Hamidi ◽  
A. Shahnazi ◽  
M. Nabid
Keyword(s):  
Energy Gap ◽  
Visible Region ◽  
Life Time ◽  
Clean Energy ◽  
Visible Radiation ◽  
Electron Hole ◽  
One Dimensional ◽  
Gold Thin Film ◽  
Excitation Processes ◽  
Hole Recombination

Abstract We can summarize the benefits of the water photocatalysis by two words: clean energy and purification of pollutants, and its problems as the large energy gap and electron-hole recombination. Scientists are still looking for a semiconductor whose energy gap lies in the visible region, with electron-hole pairs of longer life time. One of the proposed solutions in this field is combining the available semiconductors (such as TiO2) with a metal of plasmonic properties. The existing of the plasmonic metal will ensure that the visible portion of the solar region will involve in the photocatalysis action. It will be absorbed by the plasmonic metal, be transformed into a local energy that leads to excitation processes in the semiconductor. Also, the existing of the metal will guarantee a longer life time for the electron-gap pairs generated in the semiconductor, as the metal acts as a sink for the electrons generated in the semiconductor. In this paper, we created a unique photocatalyst based on one dimensional grating coated by gold thin film and covered by TiO2 cap layer. By examining the sample with visible radiation, we obtained a rate of sabotage of 25 percent within three hours.

Carbon Nanotube Electronics and Optoelectronics

MRS Bulletin ◽  
2004 ◽  
Vol 29 (6) ◽  
pp. 403-410 ◽  
Author(s):  
Phaedon Avouris
Keyword(s):  
Carbon Nanotube ◽  
High Performance ◽  
Light Sources ◽  
Metal Contacts ◽  
Electron Hole ◽  
Scaling Properties ◽  
One Dimensional ◽  
Optical Behavior ◽  
Hole Recombination

AbstractCarbon nanotubes (CNTs) are one-dimensional nanostructures with unique properties. This article discusses why CNTs provide an ideal basis for a future carbonbased nanoelectronic technology, focusing specifically on single-carbon-nanotube fieldeffect transistors (CNT-FETs). Results of transport experiments and theoretical modeling will be used to address such issues as the nature of the switching mechanism, the role of the metal contacts, the role of the environment, the FET scaling properties, and the use of these findings to produce high-performance p-type, n-type, and ambipolar CNT-FETs and simple intra-nanotube circuits. CNTs are also direct-gap nanostructures that show promise in the field of optoelectronics. This article briefly reviews their optical behavior and presents results that show that ambipolar CNT-FETs can be used to produce electrically controlled light sources based on radiative electron–hole recombination. The reverse process—that is, the generation of photocurrents by the irradiation of single CNT—FETs—and photoconductivity spectra of individual CNTs are also demonstrated.

scholarly journals Simple Preparation of Ceramic-Like Materials Based on 1D-Agx(x=0, 5, 10, 20, 40 mM)/TiO2 Nanostructures and Their Photocatalysis Performance

Crystals ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1024
Author(s):  
Noura Al Suliman ◽  
Chawki Awada ◽  
Adil Alshoaibi ◽  
Nagih M. Shaalan
Keyword(s):  
High Photocatalytic Activity ◽  
Pure Tio2 ◽  
Silver Concentration ◽  
Phonon Modes ◽  
Rutile Structure ◽  
One Dimensional ◽  
Average Size ◽  
High Silver ◽  
Tio2 Nanostructures ◽  
One Dimensional Nanostructures

Vertical Agx/TiO2 nanorods were successfully grown by a simple oxidation method of a Ti-Ag coating. The samples were grown in the phase of ceramic-like materials, which can be reusable for many cycles for photocatalysis applications. These ceramic-like Agx/TiO2 nanostructures were prepared by the spin-coating of silver nitrate onto Ti sheets. The presence of silver on the surface of the Ti sheet during the oxidation process helped in the growth of one-dimensional nanostructures. The physical properties of the fabricated ceramic-like nanostructures were studied by varying the concentration of silver on the Ti-sheet before the oxidation. One-dimensional nanostructures with an average size varying within the range of 200–500 nm were grown. The presence of silver made the nanostructure vertically directed. The nanorods were dense at the low and medium concentrations of 5, 10, and 20 mM of silver in contrary to high silver concentrations, where the nanorods were very sparse at 40 mM. Structural analysis showed the anatase and rutile structure of pure TiO2 with distinguishing diffraction lines A(101) and R(110); however, Agx/TiO2 showed a dominant orientation of A(101), confirming the 1D growth. Raman spectra confirmed the presence of TiO2 via the observation of its corresponding phonon modes. The photocatalysis properties of the fabricated ceramic-like nanostructures were performed on methylene blue (MB) as a known target dye. The low- and medium-silver-concentration samples showed a high photocatalytic activity compared to the pure and high-silver-concentration samples.

scholarly journals Electrospun Active Media Based on Polyvinylidene Fluoride (PVDF)-Graphene-TiO2 Nanocomposite Materials for Methanol and Acetaldehyde Gas-Phase Abatement

Catalysts ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1017
Author(s):  
Carlo Boaretti ◽  
Giuseppe Vitiello ◽  
Giuseppina Luciani ◽  
Alessandra Lorenzetti ◽  
Michele Modesti ◽  
...  
Keyword(s):  
Gas Phase ◽  
Polyvinylidene Fluoride ◽  
Indoor Air Pollution ◽  
Uv Light ◽  
Band Gap Energy ◽  
Electron Hole ◽  
Volatile Organic ◽  
High Concern ◽  
Nanostructured Membranes ◽  
Hole Recombination

The abatement of organic pollutants by TiO2 photocatalysis has been established as one of the benchmark applications of advanced oxidation processes for both liquid and gas phase purification. Such solution is particularly suitable for indoor air pollution where volatile organic compounds (VOCs) represent a class of chemicals of high concern for their adverse effects on both environment and human health. However, different shortcomings still affects TiO2 photocatalytic performance in terms of weak adsorptivity and fast electron-hole recombination, limiting its applicability. As a result, different strategies have been investigated over the last years in order to promote a higher TiO2 photo-efficiency. In this study we used electrospun (PVDF) nanofibers as a support for the photo catalytic system obtained by coupling graphene based materials and TiO2 during solvothermal synthesis. The resultant nanostructured membranes have been tested for acetaldehyde and methanol degradation under UV light showing an increase in the photocatalytic activity compared to bare TiO2. Such results may be ascribed to the decrease of band-gap energy and to increased electron mobility in the photocatalytic nanocomposite.

scholarly journals Boron-Doped TiO2-CNT Nanocomposites with Improved Photocatalytic Efficiency toward Photodegradation of Toluene Gas and Photo-Inactivation of Escherichia coli

Catalysts ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 632 ◽  
Author(s):  
Valmiki B. Koli ◽  
Shyue-Chu Ke ◽  
Ananta G. Dodamani ◽  
Shamkumar P. Deshmukh ◽  
Jung-Sik Kim
Keyword(s):  
Tio2 Nanoparticles ◽  
Sol Gel ◽  
Photo Luminescence ◽  
Pure Tio2 ◽  
Electron Hole ◽  
Doped Tio2 ◽  
E Coli ◽  
Boron Doped ◽  
Electron Hole Pair

An in-situ sol-gel method was used for the synthesis of boron-doped TiO2-CNT nanocomposites with varied boron concentrations from 1 to 4 mol%. The synthesized nanocomposites were characterized by various techniques, namely XRD, UV-DRS, TEM, PL, and XPS; all results show that 3 mol% B-TiO2-CNT nanocomposites have superior properties to pure TiO2, 3B-TiO2 nanoparticles, and other nanocomposites. TEM images clearly show the B-TiO2 nanoparticles decorated on the CNT surface. Photo-luminescence studies confirm that boron doping of up to 3 mol% in TiO2-CNT nanocomposites reduces the electron-hole pair recombination rate. The photocatalytic performance of the B-TiO2-CNT nanocomposites was tested against the photodegradation of toluene gas and the photocatalytic inactivation of E. coli in the presence of UV and visible light respectively. B-TiO2-CNT (3 mol%) nanocomposites show the highest photocatalytic activity.

scholarly journals Controlled Growth and Bandstructure Properties of One Dimensional Cadmium Sulfide Nanorods for Visible Photocatalytic Hydrogen Evolution Reaction

Nanomaterials ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 619 ◽  
Author(s):  
Rama Krishna Chava ◽  
Namgyu Son ◽  
Yang Soo Kim ◽  
Misook Kang
Keyword(s):  
Reaction Time ◽  
Low Cost ◽  
Chemical Properties ◽  
Metal Sulfide ◽  
H2 Evolution ◽  
Electron Hole ◽  
One Dimensional ◽  
Cds Nanorods ◽  
Hole Recombination ◽  
And Chemical Properties

One dimensional (1D) metal sulfide nanostructures are one of the most promising materials for photocatalytic water splitting reactions to produce hydrogen (H2). However, tuning the nanostructural, optical, electrical and chemical properties of metal sulfides is a challenging task for the fabrication of highly efficient photocatalysts. Herein, 1D CdS nanorods (NRs) were synthesized by a facile and low-cost solvothermal method, in which reaction time played a significant role for increasing the length of CdS NRs from 100 nm to several micrometers. It is confirmed that as the length of CdS NR increases, the visible photocatalytic H2 evolution activity also increases and the CdS NR sample obtained at 18 hr. reaction time exhibited the highest H2 evolution activity of 206.07 μmol.g−1.h−1. The higher H2 evolution activity is explained by the improved optical absorption properties, enhanced electronic bandstructure and decreased electron-hole recombination rate.

scholarly journals Engineering titania nanostructure to tune and improve its photocatalytic activity

2016 ◽  
Vol 113 (15) ◽  
pp. 3966-3971 ◽  
Author(s):  
Matteo Cargnello ◽  
Tiziano Montini ◽  
Sergey Y. Smolin ◽  
Jacqueline B. Priebe ◽  
Juan J. Delgado Jaén ◽  
...  
Keyword(s):  
Reaction Rates ◽  
Electron Hole ◽  
One Dimensional ◽  
Photocatalytic System ◽  
Wide Range ◽  
Semiconducting Nanostructures ◽  
Fuels And Chemicals ◽  
Yield Values ◽  
Reacting Systems ◽  
Hole Recombination

Photocatalytic pathways could prove crucial to the sustainable production of fuels and chemicals required for a carbon-neutral society. Electron−hole recombination is a critical problem that has, so far, limited the efficiency of the most promising photocatalytic materials. Here, we show the efficacy of anisotropy in improving charge separation and thereby boosting the activity of a titania (TiO2) photocatalytic system. Specifically, we show that H2 production in uniform, one-dimensional brookite titania nanorods is highly enhanced by engineering their length. By using complimentary characterization techniques to separately probe excited electrons and holes, we link the high observed reaction rates to the anisotropic structure, which favors efficient carrier utilization. Quantum yield values for hydrogen production from ethanol, glycerol, and glucose as high as 65%, 35%, and 6%, respectively, demonstrate the promise and generality of this approach for improving the photoactivity of semiconducting nanostructures for a wide range of reacting systems.

Luminescent Nanometer-Sized Si Crystals Formed in an amorphous Silicon Dioxide Matrk by Ion Implantation and Annealing

1995 ◽  
Vol 388 ◽  
Author(s):  
T.S. Iwayama ◽  
Y. Terao ◽  
A. Kamiya ◽  
M. Takeda ◽  
S. Nakao ◽  
...  
Keyword(s):  
Ion Implantation ◽  
Annealing Time ◽  
Band Gap Energy ◽  
Electron Hole ◽  
Quantum Confinement Effects ◽  
Transmission Electron ◽  
Si Nanocrystals ◽  
Average Size ◽  
Si Ion Implantation ◽  
Hole Recombination

AbstractSi ion implantation followed by thermal annealing has been used to synthesize luminescent nanometer-sized Si crystals in an amorphous Si02 matrix. Transmission electron microscopy indicates the formation of Si nanocrystals by annealing at 1100 °C, and the growth in average size of Si nanocrystals with increasing annealing time. the shape of the emission spectrum of the photoluminescence is found to be independent of both excitation energy and annealing time, while the excitation spectrum of photoluminescence increases as the photon energy increases and its shape depends on annealing time. the results indicate that the photons are absorbed by Si nanocrystals, for which the band-gap energy is modified by the quantum confinement effects, and the emission of photons is not due to direct electron-hole recombination inside Si nanocrystals but is related to defects probably at the interface between Si nanocrystals and Si02.

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