TiO2 Nanocomposite Materials Research Articles

RECENT PROGRESS IN THE SYNTHESIS AND PHOTOCATALYTIC DEGRADATION OF ORGANIC POLLUTANTS BY GRAPHENE-BASED TiO2 NANOCOMPOSITE: A REVIEW

Numerous sustainable water processing techniques have been widely investigated and are capable of boosting the quality of water. Among these techniques, photonanocatalysis has stood tall with great promises in the last few decades. Nonetheless, a major challenge in the environmental remediation of photocatalyst technology is to develop an ideal photocatalyst that must have excellent photocatalytic efficiency, large specific surface area, maximum harvesting of solar energy, high durability and recyclability. Due to their stability, low toxicity, low cost and superhydrophilicity TiO2 has been used by researchers as an efficient photocatalyst for the degradation of organic pollutants. Unfortunately, it suffers greatly due to its high band gap with 3.2[Formula: see text]eV, insufficient visible light response, fast photogenerated electrons and holes recombination rate and serious agglomeration. Keeping these views, the present review highlights the principal results of studies on current practical synthesis and photocatalytic activity of graphene-based TiO2 nanocomposite materials for the treatment of water. The amalgamation of graphene oxide (GO) and reduced graphene oxide (rGO) with nanoscale TiO2 particles results in synergistic properties thereby tuning and increasing the functionality of the composite. In this regard, the review also addressed the progress and insight into graphene-based TiO2 nanocomposite in photocatalytic removal of organic pollutants including basis mechanism, possible key strategies of the composite, and an overview of how to elevate efficacy. Finally, brief challenges and future perspectives in this field are also presented. Indeed, this work illustrated that graphene-based TiO2 composite nanomaterials can be a green signal in the future of photocatalysis targeting water pollution remediation.

Remarkable upgrade of hydrogen evolution activity up to 40.8 folds and mechanistic investigation of expediting charge transfer achieved by Bi2O3-modified TiO2 photocatalyst

Targeting on significantly promoting the hydrogen generation activity of titanium dioxide-based photocatalysts without the modification of noble metals by a straightforward synthetic strategy, simultaneously unveiling the photocatalytic mechanism of expedited charge transfer in photocatalyst are necessary but remains challenging. In this work, Bi2O3-modified TiO2 nanocomposite materials were directly synthesized via employing a solid-state synthesis method at mild conditions. The Bi2O3–modified TiO2 photocatalyst enable to achieve a remarkable hydrogen generation rate, dramatically outperforming commercial titanium oxide by 40.8 times. Photoelectric measurements were well matched with the broaden light absorption range and expedited charge transfer in photocatalyst, which are primarily responsible for the high-performance photocatalytic hydrogen evolution. The partially formed metallic Bi serves as a mediator between Bi2O3 and commercial TiO2 to facilitate photoexcited carriers’ separation and migration. The density functional theory simulations were further executed to calculate the differential charge distribution. It successfully unveils the electron transferring property (0.97 e−) in photocatalysts during photocatalytic process, which is well-matched with experiments derived from photoelectric measurements and uncovers the underlying photocatalytic mechanism. This work offers an efficient strategy for modifying the TiO2-based photocatalysts and dramatically achieving high-performance photocatalytic hydrogen evolution activity.

TiO2 Nanocomposite Coatings and Inactivation of Carbapenemase-Producing Klebsiella Pneumoniae Biofilm-Opportunities and Challenges.

The worldwide increase of multidrug-resistant Gram-negative bacteria is a global threat. The emergence and global spread of Klebsiella pneumoniae carbapenemase- (KPC-) producing Klebsiella pneumoniae represent a particular concern. This pathogen has increased resistance and abilities to persist in human reservoirs, in hospital environments, on medical devices, and to generate biofilms. Mortality related to this microorganism is high among immunosuppressed oncological patients and those with multiple hospitalizations and an extended stay in intensive care. There is a severe threat posed by the ability of biofilms to grow and resist antibiotics. Various nanotechnology-based strategies have been studied and developed to prevent and combat serious health problems caused by biofilm infections. The aim of this review was to evaluate the implications of nanotechnology in eradicating biofilms with KPC-producing Klebsiella pneumoniae, one of the bacteria most frequently associated with nosocomial infections in intensive care units, including in our department, and to highlight studies presenting the potential applicability of TiO2 nanocomposite materials in hospital practice. We also described the frequency of the presence of bacterial biofilms on medical surfaces, devices, and equipment. TiO2 nanocomposite coatings are one of the best long-term options for antimicrobial efficacy due to their biocompatibility, stability, corrosion resistance, and low cost; they find their applicability in hospital practice due to their critical antimicrobial role for surfaces and orthopedic and dental implants. The International Agency for Research on Cancer has recently classified titanium dioxide nanoparticles (TiO2 NPs) as possibly carcinogenic. Currently, there is an interest in the ecological, non-toxic synthesis of TiO2 nanoparticles via biological methods. Biogenic, non-toxic nanoparticles have remarkable properties due to their biocompatibility, stability, and size. Few studies have mentioned the use of nanoparticle-coated surfaces as antibiofilm agents. A literature review was performed to identify publications related to KPC-producing Klebsiella pneumoniae biofilms and antimicrobial TiO2 photocatalytic nanocomposite coatings. There are few reviews on the antibacterial and antibiofilm applications of TiO2 photocatalytic nanocomposite coatings. TiO2 nanoparticles demonstrated marked antibiofilm activity, but being nano in size, these nanoparticles can penetrate cell membranes and may initiate cellular toxicity and genotoxicity. Biogenic TiO2 nanoparticles obtained via green, ecological technology have less applicability but are actively investigated.

Thermoelectric properties and microstructure of nanocomposite Sb-GeO2 and Sb–TiO2 thin films

This work reports on fabrication and thermoelectric properties of Sb-GeO2 and Sb–TiO2 nanocomposite thin films. The formation of nanocomposite structure includes the precipitation of Sb phase and the amorphous GeO2 or TiO2 phase. In the Sb-GeO2 nanocomposite, the formation of large rhombohedral Sb grains is observed, where monoclinic Sb are formed as intermediate phase. This contributes remarkably to the elevation of conductivity, while results in the reduction of Seebeck coefficient and power factor. Contrary, the effective inhibition of Sb crystallization caused by TiO2 leads to the smaller monoclinic and rhombohedral Sb grains with homogeneous distribution in annealed Sb–TiO2 thin film. The existence of monoclinic Sb facilitates to acquire excellent thermoelectric properties. Tiny grains within the films introduce more grain boundaries, making it possible to scatter and filter low energy carriers. This leads to high conductivity, remarkable rise of the Seebeck coefficient, and excellent power factor of 765.5 μW/mK2 at 650 K. The results demonstrate that the Sb–TiO2 nanocomposite materials with high power factor can be a candidate for thermoelectric devices.

Development of a TiO2/Sepiolite Photocatalyst for the Degradation of a Persistent Organic Pollutant in Aqueous Solution.

A clay-based TiO2 nanocomposite material was synthesized by a facile method, to investigate its structure and photocatalytic efficiency. The supported TiO2 nanoparticles were generated using a sol-gel method, and subsequently, mixed with a suspension of sepiolite. The material was recovered in powder form (Mc-80) and then calcined to properly arrange the crystal lattice of the TiO2 particles for use in heterogeneous photocatalysis (Mc-80-500). A powder X-ray diffractogram of Mc-80-500 revealed a dispersion of anatase and rutile phase TiO2 particles on the clay surface, exhibiting a size in the order of 4–8 nm. TEM images of Mc-80-500 confirmed the presence of isolated TiO2 beads on the surface of the fibrous sepiolite. The specific surface area of Mc-80-500 was larger than that of raw sepiolite and that of free TiO2 nanoparticles. Mc-80-500 was found to be more efficient in heterogeneous photocatalysis compared to other TiO2 materials based on sepiolite. Total depollution of a reactive dye (Orange G) was achieved after 1 h irradiation time, which is relatively quick compared to previous reports. The photocatalyst material can be washed with distilled water without chemical additives or calcination, and can be reused several times for photocatalysis, without loss of efficiency.

N, S-CDs decorated mesoporous TiO2 composite with improved photocatalytic activity under visible light

The development of photocatalysts for efficient utilization and conversion of solar energy is the main strategy for photocatalytic degradation of pollutants. In this study, for the first time, novel N,S doped carbon quantum dots decorated mesoporous TiO2 composites (N,S-CDs/TiO2) with high specific surface areas were successfully prepared via a simple procedure, which exhibited excellent visible activity in the degradation of organic contaminants (Rhodamine B, oxytetracycline and phenol). The excellent photocatalytic performance of the catalysts was mainly ascribed to their large specific surface area, the enhanced visible light absorption and the reduced recombination rate of the photo-generated electron-hole pairs. The photocatalytic performance was affected by the N,S-CDs content and solution pH. The superoxide radicals played a dominant role in the photocatalytic process. Furthermore, a probable mechanism for the enhanced activity of N,S-CDs/TiO2 nanocomposite materials was proposed.

Improvement of Hydrophilicity for Polyamide Composite Membrane by Incorporation of Graphene Oxide-Titanium Dioxide Nanoparticles.

In this work, the polyamide (PA) membrane surface has been modified by coating of nanomaterials including graphene oxide (GO) and titanium dioxide (TiO2) to enhance membrane separation and antifouling properties. The influence of surface modification conditions on membrane characteristics has been investigated and compared with a base membrane. Membrane surface properties were determined through scanning electron microscope (SEM) images and Fourier transform infrared-attenuated total reflectance (FTIR-ATR) spectroscopy. Membrane separation performance was determined through the possibility for the removal of methylene blue (MB) in water. Membrane antifouling property was evaluated by the maintained flux ratios (%) after 120 minutes of filtration. The experimental results showed that the appearance of hydrophilic groups after coating of GO and TiO2 nanocomposite materials with or without UV irradiation onto membrane surface made an improvement in the separation property of the coated membranes. The membrane flux increased from 28% to 61%; meanwhile, the antifouling property of the coated membranes was improved clearly, especially for UV-irradiated PA/GO-TiO2 membrane.

Irradiation-catalysed degradation of methyl orange using BaF2-TiO2 nanocomposite catalysts prepared by a sol-gel method.

BaF2–TiO2 nanocomposite material (hereinafter called the composite) was prepared by a sol–gel method. The composite surface area, morphology and structure were characterized by Brunauer–Emmett–Teller method, X-ray diffraction analysis and a scanning electron microscopy. The results showed that BaF2 and TiO2 form a PN-like structure on the surface of the composite. Composites were used to catalyse the degradation of methyl orange by irradiation with ultraviolet light, γ-rays and an electron beam (EB). It was demonstrated that the composite is found to be more efficient than the prepared TiO2 and commercial P25 in the degradation of methyl orange under γ-irradiation. Increasing the composite catalyst concentration within a certain range can effectively improve the decolorization rate of the methyl orange solution. However, when the composite material is used to catalyse the degradation of organic matter in the presence of ultraviolet light or 10 MeV EB irradiation, the catalytic effect is poor or substantially ineffective. In addition, a hybrid mechanism is proposed; BaF2 absorbs γ-rays to generate radioluminescence and further excites TiO2 to generate photo-charges. Due to the heterojunction effect, the resulting photo-charge will produce more active particles. This seems to be a possible mechanism to explain γ-irradiation's catalytic behaviour.

Synthesis and characterization of Ag0(NPs)/TiO2 nanocomposite: insight studies of triclosan removal from aqueous solutions

ABSTRACT Nanocomposite mesoporous Ag0(NPs)/TiO2 thin film materials were synthesized and assessed for its efficient application in the elimination of potentially important drug triclosan from aqueous solutions. A template synthesis using the polyethylene glycol was enabled to obtain Ag0(NPs)/TiO2 nanocomposite materials where zerovalent Ag was in situ doped to the titania network. The nanocomposite materials were characterized by the scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDX), transmission electron microscope (TEM), EDX elemental mapping, X-ray diffraction (XRD) analyses and Brunauer-Emmett-Teller (BET) methods. Further, the diffuse reflectance spectroscopy (DRS) was introduced to estimate the band gap of these solids. The thin film materials were subjected to the remediation of water contaminated with triclosan using the UV-A light. The oxidative elimination of triclosan was demonstrated as a function of pH, concentration of triclosan and presence of several co-existing ions. Increase in pH (4.0–10.0) and triclosan concentrations (0.5–15.0 mg/L) had decreased significantly the percentage degradation of triclosan. The pseudo-first-order kinetics was shown in the degradation of triclosan and rate constant was significantly decreased with the increase in pollutant concentration (0.5–15.0 mg/L) and pH (4.0–10.0). The 1000 times presence of scavengers showed that •OH were, predominantly, caused the oxidation of triclosan. Moreover, multiple application of nanocomposite Ag0(NPs)/TiO2(B) revealed that the thin film was fairly intact since the photocatalytic efficiency of triclosan removal was almost unaffected.

Morphological expedient flower like nanostructures WO3–TiO2 nanocomposite material and its multi applications

The prepare WO3 -TiO2 nanocomposite material has been successfully achieved precipitation route and sonication technique. The experimental results expose that 400 °C of WO3–TiO2 nanocomposite material exhibited the higher photoatalytic activity for the degradation of azo dye Acid block 1(AB 1) under UV-Light. This nanocomposite material was characterized by High-resolution scanning electron microscopy (HR-SEM) with elementary dispersive X-ray (EDX), High-resolution transmission electron microscopy (HR-TEM), XRD analysis, photoluminescence spectroscopy (PL), UV–Vis DRS and BET. The HR-SEM images reveal that most nanoflower are linked together by an edge-to-flat-surface combination. EDX studies that Ti, O and W are in higher mediation. The HR-TEM images indicate nanorod structure. As a reaction of this nanoparticle was found to be stable and reusable. This nanoparticle was antibacterial activity and electrochemical activity showed highest activity by WO3–TiO2 compared that of TiO2 nanocomposite material was reported.

WITHDRAWN: Morphological expedient flower like nanostructures WO3-TiO2 Nanocomposite material and its multi applications

Abstract The prepare WO3 -TiO2 nanocomposite material has been successfully achieved precipitation route and sonication technique. The experimental results expose that 400 °C of WO3–TiO2 nanocomposite material exhibited the higher photoatalytic activity for the degradation of azo dye Acid block 1(AB 1) under UV-Light. This nanocomposite material was characterized by High-resolution scanning electron microscopy (HR-SEM) with elementary dispersive X-ray (EDX), High-resolution transmission electron microscopy (HR-TEM), XRD analysis, photoluminescence spectroscopy (PL), UV–Vis DRS and BET. The HR-SEM images reveal that most nanoflower are linked together by an edge-to-flat-surface combination. EDX studies that Ti, O and W are in higher mediation. The HR-TEM images indicate nanorod structure. As a reaction of this nanoparticle was found to be stable and reusable. This nanoparticle was antibacterial activity and electrochemical activity showed highest activity by WO3–TiO2 compared that of TiO2 nanocomposite material was reported.

Hierarchically structure CrO4–TiO2 nanocomposite material and its multi application

The CrO4–TiO2 nanocomposite material has been successfully achieved the precipitation route and sonication technique. The experimental results exposes that 400 °C of CrO4–TiO2 nanocomposite material exhibited in the higher photoatalytic activity for the degradation of azo dye Trypan Blue (TB) under UV-light. This nanocomposite material was characterized by High-resolution scanning electron microscopy (HR-SEM) with elementary dispersive X-ray (EDX), High-resolution transmission electron microscopy (HR-TEM), XRD analysis, photoluminescence spectroscopy (PL), UV–Vis DRS and BET-Surface analysis. The HR-SEM images reveal that most nanoflakes are linked together by an edge-to-flat-surface by the conjunction of EDX studies that Ti, O and Cr are in higher mediation. The HR-TEM images indicate a spherical and hexagonal in structure. The CrO4–TiO2 nanocomposite material was found to be the stable and reusable. This nanocomposite material was an antibacterial activity and an electrochemical activity as showed highest activity that of TiO2 nanocomposite material was reported.

Reduction of Cr6+ from Wastewater Using a Novel in Situ-Synthesized PANI/MnO2/TiO2 Nanocomposite: Renewable, Selective, Stable, and Synergistic Catalysis

An in situ synthesis of a new nanocomposite, polyaniline/manganese dioxide/titanium dioxide (PANI/MnO2/TiO2), via a one-pot oxidative polymerization method at room temperature is described in this article. The characterization was done on the synthesized nanocomposite using UV–vis, FT-IR, XRD, TGA, SEM, and TEM analysis. A superior catalytic activity is exhibited by the synergistic PANI/MnO2/TiO2 nanocomposite in the conversion of toxic Cr6+ to benign Cr3+ in comparison with PANI, MnO2, TiO2, PANI/MnO2, PANI/TiO2, MnO2/TiO2, and other nanocomposite materials reported. The reduction rate is dependent on the concentration of substrate (Cr6+), oxidant (HCOOH), and catalyst, pH, temperature, and foreign ions. The PANI/MnO2/TiO2 reveals an excellent conversion (99.9%), rate constant (15.97 × 10–2 min–1), and turnover frequency (0.3333 mmol/mg/min) in the reduction of Cr6+. The results obtained from this study illustrate that the prepared nanocomposite, PANI/MnO2/TiO2, can be very well used as an effective and ...

Poly(methyl methacrylate) with TiO2 nanoparticles inclusion for stereolitographic complete denture manufacturing − the fututre in dental care for elderly edentulous patients?

ObjectivesThe aim of this study was to obtain a Poly(methylmethacrylate) (PMMA)-TiO2 nanocomposite material with improved antibacterial characteristics, suitable for manufacturing 3D printed dental prosthesis. Methods0.2, 0.4, 0.6, 1, 2.5 by weight% of TiO2 nanoparticles have been added to the commercially available stereolithographic PMMA material and the obtained nanocomposites have been analyzed using FTIR, SEM and also tested for antimicrobial efficacy against bacterial cultures from Candida species (C. scotti). ResultsSEM images and EDX results highlighted the presence of TiO2 in PMMA nanocomposites. The elemental composition (EDX) also showed the presence of other fillers included in stereolithographic PMMA solution. FTIR analysis clearly revealed changes in polymeric matrix structure when adding TiO2 nanoparticles.Sample containing 0.4, 1 and 2.5wt% TiO2 nanoparticles inhibited the growth of Candida scotti strain in standard conditions according to the toxicity control method (DHA).Increasing quantity of nano-titania has resulted in particles fooling, forming new aggregates instead of the homogenous dispersion of nanoparticles with modified viscosity characteristics and expected lower mechanical parameters. ConclusionsSignificant improvements in polymer characteristics and nice dispersion of the TiO2 nanoparticles have been noticed for 0.4wt%, therefore it was used for stereolitographic complete denture prototyping. Clinical significanceIncorporation of TiO2 nanoparticles in PMMA polymer matrix was proved to have antibacterial effects, specifically on Candida species. The newly obtained 0.4% nanocomposite was successfully used with stereolitographic technique for complete denture manufacturing. However, mechanical and biocompatibility tests need to be performed in order to extend the clinical usage.

Synthesis of InMoO3–TiO2 nanocomposite – photocatalysis of genotoxic dye multiapplication study

Development of coupled semiconductor oxides makes considerable development in the photocatalytic functional materials. InMoO3–TiO2 nanocomposite material was synthesized by co-precipitation method and sonication technique. The synthesized nanomaterial was characterized by HR-SEM with EDX, HR-TEM, XRD, FT-RAMAN, PL, UV–vis DRS, AFM and BET surface area measurements. The photocatalytic activity of InMoO3–TiO2 nanomaterial was evaluated from the photodegradation of methyl green (MEG) under UV-light irradiation at 365nm. The photodegradation of methyl green (MEG) at various parameters are reported. The Photodegradation was found to follow the pseudo-first-order kinetics. Hydroxyl radical formation in the mechanism was confirmed by fluorescence quenching technique. It was proposed that the catalyst is found to be stable and reusable and expandable applications.

Simple synthesis of anatase/rutile/brookite TiO2 nanocomposite with superior mineralization potential for photocatalytic degradation of water pollutants

In this study, we report a simple synthesis procedure of anatase/rutile/brookite TiO2 nanocomposite material, designed for efficient transformation of emerging water pollutants (e.g., bisphenol (A)) to CO2 and H2O as final products of complete photo-oxidation. Sol–gel procedure with a subsequent hydrothermal treatment carried out at mild temperature and in the presence of 3M HCl led to the formation of TiO2 nanomaterial, which consists of anatase (43%), rutile (24%) and brookite (33%) polymorph phases within the same material. For the purpose of efficient evaluation of nanocomposite activity, individual polymorphs of anatase, rutile and brookite were also prepared using the same precursor material. Individual polymorph phases within the nanocomposite material crystallized separately and formed mixed agglomerates; the polymorphs were regularly shaped and randomly distributed in agglomerates, where some of the anatase particles exhibited truncated octahedron morphology, rutile was in the form of tetragonal prisms with pyramidal termination and brookite was shaped as blocky particles, which were found to be the smallest within the nanocomposite material (∼20nm). Newly synthesized TiO2 nanocomposite was highly active in terms of mineralization, since after 60min of irradiation under UV light almost 60% of water dissolved pollutant bisphenol A was successfully transformed into CO2 in H2O. On the other hand, the benchmark TiO2 P25 Degussa catalyst reached a lower extent of mineralization, which is due to significantly less expressed resistance to accumulation of carbonaceous deposits on the catalyst surface.

High-performance Yb, N, P-tridoped anatase-TiO2 nano-photocatalyst with visible light response by sol-solvothermal method

Novel high-performance Yb, N, P-tridoped anatase-TiO2 nano-composite photocatalysts were successfully prepared by a modified sol-solvothermal process. The physicochemical properties of as-prepared samples were characterized X-ray diffraction, N2 physical adsorption–desorption, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, UV–vis absorbance spectroscopy, photoluminescence spectroscopy and zeta potential measurements. The photocatalytic activities were evaluated by degradation of methylene blue (MB) under visible light and UV irradiation, respectively. The results indicated that Yb, N, P-tridoped TiO2 with P-doping amount of 5wt.% exhibited the highest photoactivity not only under UV irradiation but also under visible light irradiation among all as-prepared undoped, single-doped and codoped samples, which should ascribed to a synergetic effect of actions played by Yb, N and P. The possible synergetic mechanism for photocatalysis was also discussed. The excellent performance endows the Yb, N, P-tridoped anatase-TiO2 nano-photocatalysts potential in environmental purification. This research provides an effective strategy for the synthesis of novel high-performance TiO2 nano-composite photocatalytic materials.

Synthesis and Characterization of PCL/TiO2 Nanocomposites Obtained by In Situ Polymerization

The novel biodegradable poly(ε-caprolactone)/TiO2nanocomposite materials were successfully prepared via in situ in the presence of modified-TiO2initiator and Sn(Oct)2 catalyst. The relationships between morphology, molecular weight, and properties were investigated by means of SEM, TGA, DSC and GPC. A tendency of the nanoparticles to form aggregates was observed, especially at higher fillers contents. The molecular weight of PCL matrix was dependent on the amount of the TiO2fillers

Synthesis, optical, and photocatalytic properties of a new visible-light-active ZnFe2O4–TiO2 nanocomposite material

The synthesis of new ZnFe2O4-TiO2 crystalline nanocomposites with enhanced visible- light catalytic performance is reported. Zinc ferrite powders were prepared by a wet method through oxalate precursor at 400 8C during 12 h and the nanocomposite materials were obtained through TiO2 incorporation before (ZnFe2O4/TiO2) and after (TiO2/ ZnFe2O4) the ZnFe2O4 synthesis. The influence of the nanocomposite design in the structural, morphologi- cal, and optical properties of the composite oxide materials was studied, by XRD, SEM/TEM, BET measurements, and DRS. New and improved optical features were observed in the ZnFe2O4-TiO2 absorp- tion spectra comparatively with the TiO2 and ZnFe2O4 ones. These results are discussed based on the interface effect and a proposal for the photogenerated electron transitions in the ZnFe2O4-TiO2 is presented. The photocatalytic performance of the prepared sam- ples was evaluated for the methyl orange (MO) degradation process. From all the tested materials, the TiO2/ZnFe2O4 was the one with the best photo- catalytic activity, even superior to the nanocrystalline TiO2 one. 100 % reduction of the MO concentration was achieved after 10 min of UV-Vis irradiation on a 10 ppm dye aqueous solution with 0.43 g L -1 of TiO2/ZnFe2O4 catalyst. By performing visible-light experiments, it was possible to discuss the influence of the visible-light absorption, charge separation, and photogenerated charge-carrier recombination in the TiO2/ZnFe2O4 photocatalytic performance.