Mesoporous TiO2 Nanofibers Research Articles

Solar-powered commercial diesel fuel desulfurization: Exploring the factors affecting and recyclability of mesoporous Tl-doped TiO2 nanofiber photocatalysts

The study aims to fabricate mesoporous TiO2 nanofibers (NFs) with different thallium (Tl) doping ratios (1–2 wt%) using the solution electrospinning method and examine their photocatalytic oxidation activity in the desulfurization of commercial diesel fuel. The results show that the Tl doping restricted the transition of the anatase to rutile fraction, shifting it from an initial composition of 58.3% rutile and 41.7% anatase to a significantly altered state with only 2.4% rutile and 97.6% anatase. Additionally, Tl-doping resulted in a decrease in crystalline size (from 55.4 to 9.5 nm), a reduction in the band gap from 3.2 to 2.93 eV, and a decrease in the diameter of the nanofibers from 200 nm to 100 nm, compared to pristine TiO2 NFs. The most efficient photocatalyst, 1 wt% Tl-doped TiO2 NFs, demonstrated remarkable performance with 98.74% sulphur removal under Xenon lamp irradiation (450 nm, 500 Watts) for 90 min. Under sunlight, the photocatalytic oxidation activity in the desulfurization process resulted in a remarkable reduction of 99.2% in sulphur content, decreasing from 11500 ppm to 98 ppm. Notably, this photocatalyst demonstrated efficient oxidative photocatalytic desulfurization and maintained the recyclability of the solvent over eight cycles without any loss.

Fabrications of Electrospun Mesoporous TiO2 Nanofibers with Various Amounts of PVP and Photocatalytic Properties on Methylene Blue (MB) Photodegradation.

The superior chemical and electrical properties of TiO2 are considered to be suitable material for various applications, such as photoelectrodes, photocatalysts, and semiconductor gas sensors; however, it is difficult to commercialize the applications due to their low photoelectric conversion efficiency. Various solutions have been suggested and among them, the increase of active sites through surface modification is one of the most studied methods. A porous nanostructure with a large specific surface area is an attractive solution to increasing active sites, and in the electrospinning process, mesoporous nanofibers can be obtained by controlling the composition of the precursor solution. This study successfully carried out surface modification of TiO2 nanofibers by mixing polyvinylpyrrolidone with different molecular weights and using diisopropyl azodicarboxylate (DIPA). The morphology and crystallographic properties of the TiO2 samples were analyzed using a field emission electron microscope and X-ray diffraction method. The specific surface area and pore properties of the nanofiber samples were compared using the Brunauer-Emmett-Teller method. The TiO2 nanofibers fabricated by the precursor with K-30 polyvinyl pyrrolidone and diisopropyl azodicarboxylate were more porous than the TiO2 nanofibers without them. The modified nanofibers with K-30 and DIPA had a photocatalytic efficiency of 150% compared to TiO2 nanofibers. Their X-ray diffraction patterns revealed anatase peaks. The average crystallite size of the modified nanofibers was calculated to be 6.27-9.27 nm, and the specific surface area was 23.5-27.4 m2/g, which was more than 150% larger than the 17.2 m2/g of ordinary TiO2 nanofibers.

Decoration of conjugated polyquinoxaline dots on mesoporous TiO2 nanofibers for visible-light-driven photocatalysis

The photocatalysis of a heterostructured composite material composed of conjugated polymer dots (CPdots) on the surface of TiO2 nanofibers was investigated in terms of organic dye degradation, photooxidative coupling, and reduction under visible-light irradiation. Visible-light harvesting was used to transfer the excited electrons of the CPdots to visible-light-inactive, electrospun, mesoporous TiO2 nanofibers for photocatalysis. The CPdots were electrostatically bound to the TiO2 nanofibers and each CPdot was spatially located with some separation, and thus water and reagents could easily access the photocatalytic TiO2 nanofibers. This resulted in high efficiencies of dye degradation (97%), oxidative coupling (98%), and reduction (90%) under visible lighting. The nanofiber-based photocatalyst provided flexibility and easy handling, enabling repeated use simply by washing after the photocatalytic reaction.

Hydrogen producing water treatment through mesoporous TiO2 nanofibers with oriented nanocrystals

The development of well-defined TiO2 nanoarchitectures is a versatile strategy to achieve high-efficiency photocatalytic performance. In this study, mesoporous TiO2 nanofibers consisting of oriented nanocrystals were fabricated by a facile vapothermal-assisted topochemical transformation of preformed H-titanate nanobelts. The vapothermal temperature is crucial in tuning the microstructures and photocatalytic redox properties of the resulting mesoporous TiO2 nanofibers. The microstructures were characterized with XRD, TEM, XPS and nitrogen adsorption-desorption isotherms, etc. The photocatalytic activities were evaluated by photocatalytic oxidation of organic pollutant (Rhodamine B as an example) as well as photocatalytic reduction of water to generate hydrogen (H2). The nanofibers vapothermally treated at 150°C showed the highest photocatalytic activity in both oxidation and reduction reactions, 2 times higher than that of P25. The oriented alignment and suitable mesoporosity in the resulting nanofiber architecture were crucial for enhancing photocatalytic performances. The oriented alignment of anisotropic anatase nanocrystals shall facilitate faster vectorial charge transportation along the nanofibers architecture. And, the suitable mesoporosity and high surface area would also effectively enhance the mass exchange during photocatalytic reactions. We also demonstrate that efficient energy-recovering photocatalytic water treatments could be accomplished by a cascading oxic-anoxic process where the dye is degraded in the oxic phase and hydrogen is generated in the successive anoxic phase. This study showcases a novel and facile method to fabricate mesoporous TiO2 nanofibers with high photocatalytic activity for both clean energy production and environmental purification.

In Situ Synthesis of Mesoporous TiO2 Nanofibers Surface-Decorated with AuAg Alloy Nanoparticles Anchored by Heterojunction Exhibiting Enhanced Solar Active Photocatalysis.

We designed an electrospinning synthesis protocol to obtain in situ, the mesoporous TiO2 nanofibers, which are surface-decorated with plasmonic AuAg nanoparticles (AuAg-mTNF-H). Such alloy nanoparticles are found to be partially exposed on the surface of the nanofibers. Characterization by HRTEM and EDS confirmed the formation of 1:1 AuAg alloy nanoparticles on the surface of TiO2 nanofibers with heterojunction at the interfaces. On the basis of electron microscopic characterization, we proposed that, during the formation of the nanofibers, the incorporated metal ions with surface capping of negative charges migrated toward the outer surface of the nascent fibers under the influence of high positive voltage required for electrospinning. As a result, after the subsequent thermal treatment, the crystallization of TiO2 nanofibers and the formation of alloy nanoparticles took place, leading to the formation of a deep heterojunction through partial embedment of the nanoparticles. The formation of AuAg alloy also restricted the oxidation of Ag, thus making the nanoparticles highly stable in ambient condition. Accordingly, such unique AuAg-mTNF-H photocatalyst shows strong light absorption property covering the entire range of visible wavelengths with stability. The solar light harvesting property of AuAg-mTNF-H was verified by monitoring solar light induced H2 evolution via water splitting and photodecomposition of MB. In both the cases AuAg-mTNF-H showed excellent H2 evolution and photodecomposition of dye.

Mesoporous TiO2 Nanofiber as Highly Efficient Sulfur Host for Advanced Lithium\u2013Sulfur Batteries

Currently, lithium–sulfur batteries suffer from several critical limitations that hinder their practical application, such as the large volumetric expansion of electrode, poor conductivity and lower sulfur utilization. In this work, TiO2 nanofibers with mesoporous structure have been synthesized by electrospinning and heat treating. As the host material of cathode for Li–S battery, the as prepared samples with novelty structure could enhance the conductivity of cathode composite, promote the utilization of sulfur, and relieve volume expansion for improving the electrochemical property. The initial discharge capacity of TiO2/S composite cathode is 703 mAh/g and the capacity remained at 652 mAh/g after 200 cycles at 0.1 C, whose the capacity retention remains is at 92.7%, demonstrating great prospect for application in high-performance Li–S batteries.

High-Efficient Photocatalytic Performance under Visible Light of Functionalized TiO2 Nanofibers via Steam and Pressure Co-Modification

Surface structure plays a key role on the sensitization process. Mesoporous TiO2 nanofibers with high surface area and improved dye coupling mode were successfully fabricated via a simple, template...

Mesoporous TiO2 Nanofibers as Advanced Sulphur Host Materials for Lithium Storage

Mesoporous TiO2 Nanofibers as Advanced Sulphur Host Materials for Lithium Storage

Significantly Improved Photocatalytic Hydrogen Production Activity over Ultrafine Mesoporous TiO2 Nanofibers Photocatalysts

AbstractIn present work, we report the fabrication of fabrication of ultrafine mesoporous TiO2 nanofibers via a versatile foaming‐assisted electrospinning method for efficient photocatalytic hydrogen production. The diameter and the porous structure could be precisely controlled, making the controlled fabrication of mesoporous ultrafine TiO2 nanofibers. As compared to P25 as well as other TiO2 nanofiber counterparts, the as‐prepared ultrafine mesoporous TiO2 nanofibers in 85 nm diameter yielded the highest activity photocatalytic H2 release rate of 710.8 μmol • g −1• h−1, suggesting their promising applications in clean energy production.

Symbiotic organism search algorithm for simulation of J-V characteristics and optimizing internal parameters of DSSC developed using electrospun TiO2 nanofibers

In the present investigation, the recently developed, simple, robust, and powerful metaheuristic symbiotic organism search (SOS) algorithm was used for simulation of J-V characteristics and optimizing the internal parameters of the dye-sensitized solar cells (DSSCs) fabricated using electrospun 1-D mesoporous TiO2 nanofibers as photoanode. The efficiency (η = 5.80%) of the DSSC made up of TiO2 nanofibers as photoanode is found to be ∼ 21.59% higher compared to the efficiency (η = 4.77%) of the DSSC made up of TiO2 nanoparticles as photoanode. The observed high efficiency can be attributed to high dye loading as well as high electron transport in the mesoporous 1-D TiO2 nanofibers. Further, the validity and advantage of SOS algorithm are verified by simulating J-V characteristics of DSSC with Lambert-W function.

Highly efficient visible-light active photocatalyst: thoroughly mesoporous Fe doped TiO2 nanofibers

Fe-doped TiO2 nanofibers with a thoroughly mesoporous structure were prepared via a facile foaming-assisted electrospinning method. The foaming agents and FeAcAc were introduced in the raw materials to create the mesopores and incorporate the Fe dopants into the conventional solid TiO2 nanofibers, respectively, which could be accomplished simultaneously over a one-step calcination process. The photocatalytic experimental results demonstrate that the mesoporous Fe-doped TiO2 nanofibers exhibit significantly enhanced activity toward the RhB degradation and splitting water for hydrogen generation under visible-light illumination, as compared to those of Fe-doped solid and intrinsic thoroughly mesoporous counterparts. The photocatalytic mechanism is proposed that the one-dimensional mesoporous nanostructure can enhance the transportation of the reactant and products, and the Fe-doping induces the shift of the absorption edge into the visible-light range and restrains the recombination of photo-generated electrons and holes, which can synergistically improve their activity.

Water steam modified crystallization and microstructure of mesoporous TiO2 nanofibers

High surface area and high crystallinity structure of TiO2 have been concentrated for the synergistic promotion of performance in the previous studies. As high temperature heat treatment can lead the opposite development of crystallinity and surface area, high surface area TiO2 with high crystallinity at a lower temperature has been focused. In the present work, crystallized and mesoporous TiO2 nanofibers (NFs) with a high surface area were obtained by a simple water steam treatment at the low temperature of 150°C without any template agents. We demonstrated that water steam could promote not only the removal of organic component but also the crystallization and phase transformation of TiO2 NFs. The mechanisms of the low-temperature phase transformation and the formation of mesoporous of TiO2 NFs in water steam atmosphere have been analyzed. The change of the surface area and pore size distribution of the mesoporous structures with increasing temperatures were also studied. Furthermore, photocatalytic properties of the mesoporous TiO2 NFs were characterized by the photodegradation of methyl orange. It suggested that the mesoporous TiO2 NFs heat-treated at 550°C exhibited the highest photocatalytic activity for the synergistic effect of the crystallinity and surface area. In the future, such a facile, scalable, cost-effective approach can be used for the fabrication of mesoporous TiO2 NFs.

Hierarchically ordered mesoporous TiO2 nanofiber bundles derived from natural collagen fibers for lithium and sodium storage

To date, most of reported high performance TiO2 anode materials for both lithium and sodium ion batteries rely on employing tedious, high cost, and complex preparation procedures, which impede its scalable production and practical uses. Here, we demonstrate a facile synthetic strategy to engineer a one-dimensional (1D) hierarchically ordered mesoporous TiO2 nanofiber bundles (TBs) by using low-cost natural collagen fibers as the biotemplate. The as-prepared TBs are mainly constructed by hierarchical organization of ordered nanofibers (∼50–100 nm in diameter) each of which composed of well-crystallized TiO2 nanoparticles with a particle size of ∼10–20 nm, endowing a well-defined mesoporous structrue of the TBs along with a large specific surface area of 100.89 m2 g−1. This 1D hierarchical mesoporous structure is not only able to offer shortened ion diffusion paths, but also to ensure efficient electrolyte penetration for ion access and keep the structure integrity. As a result, the TBs-based anode materials show excellent electrochemical lithium and sodium storage prorperties. When evaluated in a lithium ion cell, TBs delivery a high discharge capacity of 120 mAh g−1 under 5C rate, and exhibits long-term cycling stability with an extremely low capacity decay of 0.03% over 500 cycles. Even for sodium ion cell tests, a remarkable capacity of nearly 130 mAh g−1 is also achieved at a current density of 200 mA g−1, suggesting the reversible sodium storage capability of the TBs. This synthetic approach is promising for developing low cost, high efficient and practical TiO2 anode materials available for lithium and sodium ion batteries.

Fabrication of hierarchical TiO2 nanofibers by microemulsion electrospinning for photocatalysis applications

Abstract Hierarchical titanium dioxide (TiO2) nanofibers with distinctive microstructures were fabricated successfully via microemulsion electrospinning (ME-ES) followed by pyrolysis. The chemical composition, morphology and microstructure of hierarchical TiO2 nanofibers were characterized by Fourier transfer infrared (FT-IR), Energy dispersive X-ray (EDX) spectroscopy, Field emission-scanning electron microscopy (FE-SEM) and Transmission electron microscopy (TEM), respectively. The photocatalytic performances were evaluated by decomposing methylene blue (MB) aqueous solution with UV light embedded with 365 nm light filter as the light sources. The results indicated that multi-channel, hollow, irregular hollow and mesoporous TiO2 nanofibers with mixed crystalline were obtained only by adjusting the ratio of tetrabutyl titanate (TBT)/paraffin oil in the microemulsion system. In addition, the pores in the TiO2 nanofibers were axial-aligned for both the multi-channel and hollow nanofibers. All the TiO2 nanofibers prepared by microemulsion electrospinning displayed improved photocatalytic performances compared with the solid TiO2 nanofibers. The results has proved that microemulsion electrospinning is indeed a simple and convenient method for fabricating hierarchical TiO2 nanofibers with improved photocatalytic performances.

Electrospun nanoporous TiO2 nanofibers wrapped with reduced graphene oxide for enhanced and rapid lithium-ion storage

A high reversible Li-ion storage capacity (200mAh/g) with C/10 rate and good rate capability is achieved in reduced graphene oxide (rGO) wrapped anatase mesoporous TiO2 nanofiber anodes fabricated by electrospinning. X-ray analysis of rGO wrapped TiO2 nanofibers confirmed the crystalline anatase structure of TiO2, while Raman spectroscopy established high frequency shift caused by the interaction of TiO2 with 2–4 layers of rGO. FT-IR analysis of rGO wrapped TiO2 nanofibers revealed disappearance of CC, CO, and COH stretching frequencies suggesting the successful reduction of GO to graphene, further confirmed by X-ray Photoelectron spectroscopy. The BET surface area of TiO2 nanofibers (54m2g−1) increased to 105m2g−1 after wrapping rGO leading to mesoporous structure with pore diameters 5–20nm, complementary observations with scanning and transmission electron microscopies. The oxidation/reduction peaks revealed lithium insertion and lithium extraction mechanism, from 1D TiO2 fibers with superior electrode/electrolyte contacts, with shorter Li-ion diffusion length and improved ionic conductivity. Successful anchoring of rGO on TiO2 nanofiber with Ti3+-C bonds energetically favors the electrochemical reaction yielding high rate and specific TiO2 capacity as a promising anode of lithium ion battery.

Nitrogen-Doped Ordered Mesoporous Anatase TiO2 Nanofibers as Anode Materials for High Performance Sodium-Ion Batteries.

Nitrogen-doped ordered mesoporous TiO2 nanofibers (N-MTO) have been fabricated by electrospinning and subsequent nitridation treatment. The N-doping in TiO2 leads to the formation of Ti(3+) , resulting in the improved electron conductivity of TiO2 . In addition, one-dimensional (1D) N-MTO nanostructure possesses very short diffusion length of Na(+) /e(-) in N-MTO, easy access of electrolyte, and high conductivity transport of electrons along the percolating fibers. The N-MTO shows excellent sodium storage performance.

Mesoporous TiO2 nanofibers with controllable Au loadings for catalytic reduction of 4-nitrophenol

The Au/TiO2 hybrid nanofibers composed of mesoporous TiO2 nanofibers and Au nanoparticles were synchronously fabricated by integrating a facile electrospinning technique and subsequent annealing in air. The Au loading content in the hybrid nanofibers was regulated by varying the dosage of chlorauric acid added in the precursor solution. The compositions, microstructures and optical response properties of the Au/TiO2 hybrid nanofibers were characterized. The UV–vis spectra of the as-prepared hybrid fibers reveal two absorption bands belonging to the band gap absorption of TiO2 and the surface plasmon resonance (SPR) of Au nanoparticles. For the catalytic reduction of 4-nitrophenol to 4-aminophenol by sodium borohydride, the apparent reaction rate constant is raised but TOF value of the catalyst decreases, as the Au loading amount in the hybrid fibers increases. This is because the Au nanoparticles with smaller sizes have higher total surface areas at the same weight and therefore show higher catalytic activity. This method for producing Au/TiO2 hybrid nanofibers is versatile and can be extended to the fabrication of other hybrid nanofibers composed of various noble metal nanoparticles and other mesoporous metal oxide nanofibers, designing of highly efficient catalysts for more important chemical reactions.

Facile Synthesis of Mesoporous MoS2‐TiO2 Nanofibers for Ultrastable Lithium Ion Battery Anodes

AbstractTiO2 hybrid nanocomposites are promising electrode materials for lithium‐ion batteries because of the large specific capacity, excellent rate capability, and high cycling stability. We have developed an effective facile incipient wetness impregnation method that can be used to fabricate novel mesoporous MoS2–TiO2 fibrous nanocomposites. The MoS2–TiO2 nanocomposites exhibited notable electrochemical performance with a high capacity of 120 mA h g−1 at a rate of 40 C and long‐term, stable capacity of 124 mA h g−1 with a capacity retention of 75.2 % after 1000 cycles. These results suggest that the structure of mesoporous TiO2 nanofibers composited with a thin, uniform, well‐dispersed MoS2 layer improve the rate performance and cycling stability. Such good performance may be derived from the dispersed MoS2 layer, which accelerates the surface electrochemical reactions and offers a stable structure.

Superior photocatalytic performance of reduced graphene oxide wrapped electrospun anatase mesoporous TiO2 nanofibers

Reduced graphene oxide (rGO) wrapped with anatase mesoporous TiO2 nanofibers (TNFs) were synthesized, by using the electrospinning technique along with easy chemical methods. The structural and morphological results demonstrate the success of wrapping of nanofibers with rGO. Wrapping with rGO leads to an efficient photogenerated charge carrier separation across the interface of rGO and TNFs. As a result, the photocatalytic activity of the composites is enhanced to 96% compared to only 43% for TNFs alone, in the photo degradation of methyl orange. This simple synthetic method can be applied not only to wrap rGO over other nanostructures of different morphology, but also for enhancing the properties of multifunctional materials.

Enhanced photocatalytic CO₂-reduction activity of electrospun mesoporous TiO₂ nanofibers by solvothermal treatment.

Photocatalytic reduction of CO2 into renewable hydrocarbon fuels using semiconductor photocatalysts is considered as a potential solution to the energy deficiency and greenhouse effect. In this work, mesoporous TiO2 nanofibers with high specific surface areas and abundant surface hydroxyl groups are prepared using an electrospinning strategy combined with a subsequent calcination process, followed by a solvothermal treatment. The solvothermally treated mesoporous TiO2 nanofibers exhibit excellent photocatalytic performance on CO2 reduction into hydrocarbon fuels. The significantly improved photocatalytic activity can be attributed to the enhanced CO2 adsorption capacity and the improved charge separation after solvothermal treatment. The highest activity is achieved for the sample with a 2-h solvothermal treatment, showing 6- and 25-fold higher CH4 production rate than those of TiO2 nanofibers without solvothermal treatment and P25, respectively. This work may also provide a prototype for studying the effect of solvothermal treatment on the structure and photocatalytic activity of semiconductor photocatalysts.