Titanate Nanotubes Research Articles

Behavior of the Energy Levels of Hydrogen Titanate Nanotubes Decorated with Au, Ag, Mn, and Ni and Their Effect on the H2 Evolution

Behavior of the Energy Levels of Hydrogen Titanate Nanotubes Decorated with Au, Ag, Mn, and Ni and Their Effect on the H2 Evolution

Direct fabrication of graphitic carbon nitride-wrapped titanate nanotube arrays toward photoelectrochemical water oxidation in neutral medium

Direct fabrication of graphitic carbon nitride-wrapped titanate nanotube arrays toward photoelectrochemical water oxidation in neutral medium

Depositation of sodium titanate nanotubes: superhydrophilic surface and antibacterial approach

Here, the present work aimed to investigate the wettability of the sodium titanate nanotubes films and evaluate the antibacterial activity of the nanotubes powder under light and bacterial adhesion assay. The films were deposited by electrophoretic deposition technique on FTO glass and sodium titanate nanotubes were synthesized via microwave-assisted hydrothermal. Raman analysis, X-ray Diffraction, and Scanning Electron Microscopy confirmed the deposition of the nanotubes. Atomic Force Microscopy showed that the roughness of the films is superior to the roughness of the FTO. The water contact angle decreases from 37.85° (clean FTO) to 9.53° after deposition of the nanotubes. It reaches 0.00° after irradiation under ultraviolet light. The surface free energy of the FTO increases from 69.91 mN/m (clean FTO) to 81.43 mN/m after nanotube deposition and irradiation. Adhesion assays showed inhibition in Escherichia coli and a significant reduction in the adhesion of Staphylococcus aureus on the nanotubes films. Furthermore, in the antibacterial tests performed via the direct contact method showed a considerable inhibitory effect against E. coli (η=25.4%) under UV–Visible light than the dark conditions (η=4.1%). Therefore, nanotubes induce the photoinduced superhydrophilicity of the surface and enhanced inhibitory effect on E. coli after exposure under light due to the production of reactive oxygen species. E. coli and S. aureus have their adhesion inhibited in the nanotubes films probably due to high wettability and roughness at the nanoscale of the films.

Titanate Nanotubes-Based Heterogeneous Catalyst for Efficient Production of Biomass Derived Chemicals

The development of efficient heterogeneous catalytic system to convert plentiful biomass to renewable bio-chemicals is urgent need. Titanate nanotubes-based materials obtained from hydrothermal treatment have been reported as low-cost and efficient catalytic materials in chemical syntheses for bio-based chemicals production with interesting catalytic performance. This mini-review expressly revealed the significance and potential of using titanate nanotubes based material as sustainable and environmentally benign solid catalysts/supports for synthesis of various bio-based chemicals, including glycerol-derived solketal, jet fuel range alkanes precursors, biomass-derived esters, aldehydes, aromatic compounds and so on. From the current knowledge on titanate nanotubes-based material via hydrothermal method here summarized, the future lines of research in the field of catalysis/supports for bio-based chemicals production are outlined.

Photocatalytic degradation of GenX in water using a new adsorptive photocatalyst

GenX, the ammonium salt of hexafluoropropylene oxide dimer acid, has been used as a replacement for perfluorooctanoic acid. Due to its widespread uses, GenX has been detected in waters around the world amid growing concerns about its persistence and adverse health effects. As relevant regulations are rapidly evolving, new technologies are needed to cost-effectively remove and degrade GenX. In this study, we developed an adsorptive photocatalyst by depositing a small amount (3 wt.%) of bismuth (Bi) onto activated-carbon supported titanate nanotubes, Bi/TNTs@AC, and tested the material for adsorption and subsequent solid-phase photodegradation of GenX. Bi/TNTs@AC at 1 g/L was able to adsorb GenX (100 µg/L, pH 7.0) within 1 h, and then degrade 70.0% and mineralize 42.7% of pre-sorbed GenX under UV (254 nm) in 4 h. The efficient degradation also regenerated the material, allowing for repeated uses without chemical regeneration. Material characterizations revealed that the active components of Bi/TNTs@AC included activated carbon, anatase, and Bi nanoparticles with a metallic Bi core and an amorphous Bi2O3 shell. Electron paramagnetic resonance spin-trapping, UV-vis diffuse reflectance spectrometry, and photoluminescence analyses indicated the superior photoactivity of Bi/TNTs@AC was attributed to enhanced light harvesting and generation of charge carriers due to the UV-induced surface plasmon resonance effect, which was enabled by the metallic Bi nanoparticles. •OH radicals and photogenerated holes (h+) were responsible for degradation of GenX. Based on the analysis of degradation byproducts and density functional theory calculations, photocatalytic degradation of GenX started with cleavage of the carboxyl group and/or ether group by •OH, h+, and/or eaq−, and the resulting intermediates were transformed into shorter-chain fluorochemicals following the stepwise defluorination mechanism. Bi/TNTs@AC holds the potential for more cost-effective degradation of GenX and other per- and polyfluorinated alkyl substances.

Efficient Oxidation of Paracetamol Triggered by Molecular-Oxygen Activation at β-Cyclodextrin-Modified Titanate Nanotubes.

Titanate nanotubes (TNTs) were coated with a cyclic oligosaccharide (carboxymethyl-β-cyclodextrin, CM-β-CD) to obtain a photocatalyst (CM-β-CD-TNT) for efficiently activating molecular oxygen and removing the target contaminant. The hydrophobic cavity and the large specific surface area of the photocatalyst provide abundant active sites for activating molecular oxygen. The free radical capture experiment and quenching experiment showed that cyclodextrin could facilitate adsorption and activation of molecular oxygen to produce O2 .- . Therefore, compared with the pristine TNT, CM-β-CD-TNT accelerated the oxidation efficiency of paracetamol (APAP) by 3.4 times. Moreover, the ring cleavage reaction induced by CM-β-CD-TNT effectively reduced the acute toxicity of wastewater containing APAP. Furthermore, 100% of bisphenol A (BPA), bisphenol S (BPS), phenol, 2,4-dichlorophen (2,4-DCP), and carbamazepine (CBZ) were degraded by CM-β-CD-TNT after 2.5 h ultraviolet (UV) light irradiation. This strategy provides a new dimension for the advanced treatment of organic wastewater by organic macrocyclic molecule-modified materials.

Removal of Methyl Violet Dye by Adsorption Process on Hydrogen Titanate Nanotubes: Experimental-Theoretical Study

Removal of Methyl Violet Dye by Adsorption Process on Hydrogen Titanate Nanotubes: Experimental-Theoretical Study

Future Paradigm of 3D Printed Ni-Based Metal Organic Framework Catalysts for Dry Methane Reforming: Techno-economic and Environmental Analyses.

Dry reforming of biogas is referred as an attractive path for sustainable H2 production over decades. Meanwhile, in the Malaysian context, the abundance of palm oil mill effluent (POME) produced annually is deemed as a potential renewable source for renewable energy generation. Conventionally, nickel (Ni) is the most common catalyst used in the industrial-scale dry reforming of methane (DRM) to yield H2, but it is subject to the drawbacks of sintering and deactivation after a long reaction time at high temperatures (>500 °C). Therefore, this work aims to provide an insight on the feasibility of the application of modified Ni-based catalysts in DRM, specifically in the economic and environmental aspects. From the benchmarking study of various Ni-based catalysts (e.g., bimetallic (Ni-Ce/Al2O3), alumina support (Ni/Al2O3), protonated titanate nanotube (Ni-HTNT), and unsupported), the Ni-MOF catalyst, notably, had proven its prominence in both economic and environmental aspects on the same basis of 10 tonnes of H2 production. The MOF-based catalyst not only possessed a better economic performance (net present value 61.86%, 140%, and 563.08% higher than that of Ni-Ce/Al2O3, Ni/Al2O3, and Ni-HTNT) but also had relatively lower carbon emissions (13.18%, 20.09%, and 75.72% lower than that of Ni/Al2O3, Ni-HTNT, and unsupported Ni). This work also accounted for 3D printing technology for the mass production of Ni-MOF catalysts, where the net present value was 2 to 3% higher than that of the conventional production method. Additionally, sensitivity analysis showed that the H2 price has the greatest impact on the feasibility of DRM as compared to other cost factors.

Physical and mechanical properties of hybridized elastomeric foam based on ethylene-propylene-diene-monomer, multiwall carbon nanotube, and barium titanate

The use of hybrid fillers in rubbers can provide additional benefits to rubber foams compared to individual micro- or nano-scale particles due to an optimum packaging and synergic effects. The present work reports the development of vulcanized ethylene-propylene-diene-monomer nanocomposite hybrid foams filled with barium titanate and multiwall carbon nanotube (BT/MWCNT), prepared via a scalable protocol. The developed foams presented a high shear-thinning behavior, suggesting the formation of a 3D interconnected physical network of MWCNT within the polymer matrix. This network resulted in a notable improvement of the mechanical properties under tension and compression with increasing of MWCNT content. Also, the incorporation of MWCNT and BT enhanced thermal stability and thermal conductivity. Meanwhile, BT did not show any influence on the measured physical properties, due to the lack of interaction between BT and the EPDM matrix.

Autoclave and pulsed ultrasound cavitation based thermal activation of persulfate for regeneration of hydrogen titanate nanotubes as recyclable dye adsorbent.

In the dye removal application, regeneration of hydrogen titanate nanotubes (HTN, H2Ti3O7) has been achieved via thermal activation of persulfate anion (PS, S2O82-) by using the conventional hot plate technique which has limitations from the commercial perspective since it does not provide any precise control over the thermal generation process typically during the scale-up operation. To overcome this drawback, HTN have been synthesized via hydrothermal process which exhibit the methylene blue (MB) adsorption of 93% at the initial dye concentration and solution pH of 90µM and 10 respectively. HTN have been regenerated via the thermal activation of PS by varying its initial concentration and regeneration temperature, within the range of 0.27-1 wt% and 40-80°C, under the thermal conditions set by the autoclave and pulsed ultrasound (US) cavitation process. The results of recycling experiments suggest that the optimum values of initial PS concentration and temperature, for the regeneration of HTN under the autoclave conditions, are 1 wt% and 70°C with the maximum MB adsorption of 92%, while, the corresponding values for the pulsed US cavitation process are 1 wt%, 80°C, and 91% respectively. Thus, the regeneration and recycling of HTN have been successfully demonstrated by using the autoclave and pulsed US cavitation process. Under the optimum conditions, MB degradation involves the generation and attack of SO4•- for both the thermal generation techniques. The regeneration techniques developed here may be utilized in future during the scale-up operation and also for the regeneration of adsorbents besides HTN.

Mechanism of One-Step Hydrothermally Synthesized Titanate Catalysts for Ozonation.

A titanate nanotube catalyst for ozonation was synthesized with a simple one-step NaOH hydrothermal treatment without energy-consuming calcination. The synthesized titania catalysts were characterized by X-ray diffraction (XRD), Raman, porosimetry analysis, high-resolution transmission electron microscopy (HR-TEM), Fourier transformed infrared (FTIR), and electron paramagnetic resonance (EPR) analysis. The catalyst treated with a higher concentration of NaOH was found to be more catalytically active for phenol removal due to its higher titanate content that would facilitate more OH groups on its surface. Furthermore, the main active oxidizing species of the catalytic ozonation process were recognized as singlet oxygen and superoxide radical, while the hydroxyl radical may only play a minor role. This work provides further support for the correlation between the properties of titania and catalytic performance, which is significant for understanding the mechanism of catalytic ozonation with titania-based materials.

Titanate nanotubes: Effect of rare earth insertion, thermal treatment and their optical properties

Titanate nanotubes (TiNTs) were synthesized by the microwave-assisted alkaline hydrothermal method, ionically exchanged with rare earth ions (RE) (La3+, Ce4+, Pr3+, Nd3+, Er3+, and Yb3+) (RE-TiNTs), and subjected to thermal treatment. The thermal treatment aimed at structural and morphological changes in the nanotubes in order to generate differentiated optical properties. The RE-TiNTs displayed significant changes in optical absorption and PL intensity compared to the NaTiNTs, which correlated with the temperature of treatment. The PL spectra of the samples was related to the morphological and structural changes of the TiNTs intercalated with RE, indicating that the RE insertion together with the existing oxygen vacancies directly influence the PL emission. The optimization/engineering of the optical properties of the produced nanomaterials could enable their use in applications in optoelectronics and photonics, such as photoluminescent devices, displays, and lasers.

Concentrate and degrade PFOA with a photo-regenerable composite of In-doped TNTs@AC

“Concentrate-and-degrade” is an effective strategy to promote mass transfer and degradation of pollutants in photocatalytic systems, yet suitable and cost-effective photocatalysts are required to practice the new concept. In this study, we doped a post-transition metal of Indium (In) on a novel composite adsorptive photocatalyst, activated carbon-supported titanate nanotubes (TNTs@AC), to effectively degrade perfluorooctanoic acid (PFOA). In/TNTs@AC exhibited both excellent PFOA adsorption (>99% in 30 min) and photodegradation (>99% in 4 h) under optimal conditions (25 °C, pH 7, 1 atm, 1 g/L catalyst, 0.1 mg/L PFOA, 254 nm). The heterojunction structure of the composite facilitated a cooperative adsorption mode of PFOA, i.e., binding of the carboxylic head group of PFOA to the metal oxide and attachment of the hydrophobic tail to AC. The resulting side-on adsorption mode facilitates the electron (e‒) transfer from the carboxylic head to the photogenerated hole (h+), which was the major oxidant verified by scavenger tests. Furthermore, the presence of In enables direct electron transfer and facilitates the subsequent stepwise defluorination. Finally, In/TNTs@AC was amenable to repeated uses in four consecutive adsorption-photodegradation runs. The findings showed that adsorptive photocatalysts can be prepared by hybridization of carbon and photoactive semiconductors and the enabled “concentrate-and-degrade” strategy is promising for the removal and degradation of trace levels of PFOA from polluted waters.

Formation of core-shell nanostructure through wrapping of cuprous oxide nanowires by hydrogen titanate nanotubes

Recent developments of heterojunction-based devices through bottom-up approach such as sensors, light-emitters, energy generation and storage have emerged with great interest due to their wide range of operation and application related flexibilities. This work demonstrates how as-grown hydrogen titanate nanotubes (HTNT) bend and wrap on pristine curpous oxide nanowires (CONW) when mixed together. The unique architecture of wrapping followed by junction formation enhances the active surface area and reduces the contact resistance between the adjacent CONW and HTNT. Such a film upon further ion beam irradiation produces a large-scale network of hetero- and homo-junctions. This newly formed thin film surface upon irradiation shows strong water repelling properties and higher electrical conductivity. The wrapping mechanism, bond formation and the change of conductivity are explained using first principles calculations. The ion beam modifications and large-scale joining are predicted by state-of-the-art TRI3DYN simulation, which is based on binary collision approximation and simulated in a Monte Carlo approach. The observed wrapping and heterojunction are expected to provide excellent mechanical strength and flexibility, which are suitable for fabrication of flexible electronic devices.

Enhanced Catalytic Activity and SO2/H2O Tolerance for Selective Catalytic Reduction of NOx with NH3 over Titanate Nanotubes Supported MnOx–CeO2 Catalyst at Low Temperature

Enhanced Catalytic Activity and SO2/H2O Tolerance for Selective Catalytic Reduction of NOx with NH3 over Titanate Nanotubes Supported MnOx–CeO2 Catalyst at Low Temperature

Performance of TFN nanofiltration membranes through embedding internally modified titanate nanotubes

Performance of TFN nanofiltration membranes through embedding internally modified titanate nanotubes

Removal of Cd2+ from water containing Ca2+ and Mg2+ using titanate nanotubes modified by carbon.

Calcium and magnesium ions usually exist in natural water. When Cd2+ is removed from water by adsorption, it will be inhibited by these two ions. Titanate nanotubes (TNTs) have an effective adsorption capacity for Cd2+ due to extraordinary ion exchange property. However, TNTs also adsorb Ca2+ and Mg2+ in water. In this study, carbon-modified TNT (TNT/C) and TNT/C further treated with acid (TNT/HC) were synthesized by hydrothermal synthesis. The transmission electron microscope (TEM) images show that TNT/C or TNT/HC still keep nanotube morphology. The experimental results show the order of adsorption amount to Cd2+ is TNT (171.56mg/g) > TNT/C (166mg/g) > TNT/HC (159.88mg/g) when there is no Ca2+ or Mg2+. But when there is 0.1M Ca2+ or Mg2+ in the water, the order of Cd2+ adsorption capacity becomes TNT/HC (44.28, 49.04mg/g) > TNT/C (58.84, 69.32mg/g) > TNT (65.52, 70.6mg/g). It indicates that the surface carbon modification can alleviate the hindrance of Ca2+ or Mg2+ to Cd2+ removal. This is because the carbon on the surface of TNT captured part of Ca2+ or Mg2+; it made more Cd2+ be successfully absorbed by TNT through ion exchange. This mechanism was confirmed by the X-ray photoelectron spectroscopy (XPS) spectra analysis. The results of this paper can provide ideas for the adsorption and removal of Cd2+ in water in the presence of Ca2+ or Mg2+.

“Dual-functional” strontium titanate nanotubes designed based on fusion peptides simultaneously enhancing anti-infection and osseointegration

Currently, there is an increasing clinical demand for implants that effectively resist bacterial infections while promoting osseointegration. In this study, the fusion peptide technology was used to linearly fuse the antimicrobial peptide (AMP, HHC36) and the bone-promoting peptide (RGD), so that the titanium (Ti)-based implant modified by the polypeptide had the dual function of “antibacterial-promoting bone”. Firstly, self-organized vertically-oriented strontium-doped titanium dioxide nanotubes (STN) were manufactured by anodizing and hydrothermal synthesis methods. Secondly, the fusion peptide (HHC36-RGD) was loaded into the tubular structure by a simple vacuum-assisted physical adsorption method. Finally, STN loaded with HHC36-RGD (H-R-STN) was obtained. The characterization results demonstrated that the surface of the H-R-STN had a roughness and hydrophilicity that promoted cell adhesion. Additionally, electrochemical tests showed that H-R-STN coating can reduce the corrosion rate of pure Ti. The fusion peptide and Sr2+ in H-R-STN were released in the initial fast and subsequent slow kinetic model. Expected, H-R-STN can kill more than 99% of clinically common pathogenic bacteria (Staphylococcus aureus and Escherichia coli), and significantly inhibit the formation of bacterial biofilms. Simultaneously, under the synergistic effect of RGD in the fusion peptide and strontium in STN, H-R-STN markedly promoted the adhesion and proliferation of mouse osteoblasts, and significantly promoted osteogenic markers (alkaline phosphatase, runt-related transcription, collagen, mineralization) expression. In summary, the bifunctional titanium-based implant constructed by H-R-STN in this article can effectively prevent bacterial infections and promote early osseointegration. The main advantage of the titanium surface treatment method of the study was that its simplicity, low cost, especially its versatility made it a promising anti-infective bone repair material.

Facile Synthesis of Graphene Oxide/Titanate Nanotube Composites and Their Application for Cobalt(II) Removal

In this work, the novel graphene oxide/titanate nanotubes (GTNT) composites were synthesized through a facile and high-yield alkaline hydrothermal method. SEM, TEM, XRD, BET, and TGA/DTA were applied to study the morphology and structure of the GTNT composites. The results show that a huge number of titanate nanotubes are closely attached to the graphene sheet structure and overlap each other. This hierarchical morphology endows the GTNT composites with not only the high specific surface area of 236.9 m2/g but also abundant porous structure, both of which are benefit for Co(II) adsorption. The batch adsorption experiments demonstrate that the GTNT composites have a high adsorption capacity and rapid kinetics for Co(II) adsorption (10 min for equilibrium). The adsorption capacity of the GTNT composites reaches 211.1 mg/g. The adsorption kinetics of the GTNT composites fits well to the pseudo-second-order model, while the adsorption isotherm of which fits well to the Langmuir model. The adsorption performance of Co(II) ions on the GTNT composites has a great relationship with the pH value, in the pH range of 1–7, the Co(II) adsorption capacity of the GTNT composites greatly increases with the increase of the pH value. In addition, the effect of coexisting anions on fluoride removal is also investigated. Na+, K+, and Mg2+ ions have shown a negligible effect on the Co(II) adsorption efficiency of the GTNT composites. However, the existences of Cu2+, Cd2+, and Pb2+ ions would clearly have an effect on the Co(II) adsorption of the GTNT composites. The adsorption mechanism is also discussed. It is believed that the GTNT composites can be considered as a potential functional material for removing the radioactive metals containing wastewater.

Application of Titanate Nanotubes for Photocatalytic Decontamination in Water: Challenges and Prospects

Application of Titanate Nanotubes for Photocatalytic Decontamination in Water: Challenges and Prospects