Thickness Of TiO2 Shell Research Articles

Preparation of Au@TiO2 yolk-shell nanocomposites for solar-light degradation of methylene blue

A novel synthetic approach has been developed to prepare Au@TiO2 yolk-shell (Au@TiO2-YS) structures using silica as a template with controllable size, shape, crystal phase. This approach shows a few unique features, including tunable TiO2 shell thickness, high repeatability, low cost, and easy operation. The morphology, composition and the corresponding properties were characterized by several advanced techniques, such as TEM, XRD, and UV-vis spectroscopy. The Au@TiO2-YS structures consist of Au NPs as cores and TiO2 hollow spheres as shells. The Au NPs can be controlled in various diameters (e.g., 100 nm, 50nm, and 30 nm), wh ile the TiO2 shell can form cavities with diameters of 255 nm and the thickness of ∼45 nm. The absorption peak of the product can be changed by adjusting the size of Au cores. In addition, the photocatalytic activities of the synthesized composites were systematically measured by degrading methylene blue (MB) under simulated solar light irradiation. The photocatalytic performance test reveals that the reaction kinetic constants of the Au@TiO2-YS structures with different Au core sizes are superior to that of the TiO2 hollow spheres (0.00521 min−1). A mong the yolk-shell structures, the YS-50 show highest kinetic constant (0.00704 min−1), wh ich is 1.35 times higher than that of pure TiO2 hollow spheres. These findings provide an effective way for design and construction of TiO2-based photocatalysts for solar-light degradation of organic pollutant.

Constructing a Z-scheme Heterojunction of Egg-Like Core@shell CdS@TiO₂ Photocatalyst via a Facile Reflux Method for Enhanced Photocatalytic Performance.

A well designed and accurate method of control of different shell thickness and electronic transmission in a Z-scheme core@shell system is conducive to obtaining an optimum photocatalytic performance. Herein, the Z-scheme heterojunction of egg-like core@shell CdS@TiO2photocatalysts with controlled shell thickness (13 nm, 15 nm, 17 nm, 22 nm) were synthesized by a facile reflux method, and the CdS@TiO2 structure was proved by a series of characterizations. The photodegradation ratio on methylene blue and tetracycline hydrochloride over the 0.10CdS@TiO2 composites with TiO2 shell thickness of 17 nm reached 90% in 250 min and 91% in 5 min, respectively, which was almost 9.8 times and 2.6 times than that of TiO2 and CdS on rhodamine B respectively under visible light. Besides, the higher total organic carbon removal ratio indicated that most of the pollutants were degraded to CO2 and H2O. The Z-scheme electronic transfer pathway was studied through radical species trapping experiments and electron spin resonance spectroscopy. Moreover, the relationship between shell thickness and photocatalytic activity demonstrated that different shell thickness affects the separation of the electron and holes, and therefore affected the photocatalytic performance. In addition, the effects of pollutants concentration, pH, and inorganic anions on photocatalytic performance were also investigated. This work can provide a novel idea for a well designed Z-scheme heterojunction of core@shell photocatalysts, and the study of photocatalytic performance under different factors has guiding significance for the treatment of actual wastewater.

Three-dimensional hollow SnO2@TiO2 spheres encapsulated in reduced graphene oxide aerogels as promising anodes for lithium-ion storage

Three-dimensional hollow SnO2@TiO2 spheres encapsulated in reduced graphene oxide aerogels (HSTGAs) were successfully fabricated through self-assembly from SnO2@TiO2 hollow spheres and graphene oxide nanosheets using a simple hydrothermal process. The hollow spheres possess an average size of 360 nm. The thickness of SnO2 shell is 10–15 nm, and the thickness of TiO2 shell is 20–35 nm. The TiO2 shell was anchored onto the surface of hollow SnO2 spheres to effectively limit volume change. Afterward, hollow SnO2@TiO2 spheres were wrapped in graphene oxide nanosheets to build a three-dimensional conductive structure. The applications of HSTGAs as anode for lithium ion storage were explored. Systematic electrochemical results show that HSTGAs electrode maintains a high-discharge capacity of about 668.2 mA h g−1 at 100 mA g−1 after 200 cycles. Compared with pure metal oxide hollow spheres, HSTGAs can greatly enhance the electrochemical performance due to the synergistic effects of metal oxide hollow spheres and graphene oxide nanosheets. HSTGAs are prospective multifunctional nanomaterials that can be used to solve the current energy storage issues.

Electrochemical study of the Li-ion storage process in MWCNT@TiO2–SiO2 composites

Tuning the Li-ion storage mechanism from battery-like to pseudocapacitive is a current strategy to improve the rate capability of intercalation materials. A widespread methodology is decreasing the particle size of the active material, offering larger number of active sites available to storage Li-ions on the surface of the materials. Core@shell composites were obtained by hydrolyzing TTIP and TEOS, at different ratios, over previously dispersed home-made MWCNTs in Isopropanol, in order to obtain a TiO2 shell modified with 1 mol% and 9 mol% of SiO2. This led to a detriment in the anatase crystalline size (TEM and XRD) and an increment in the specific surface area (BET) of the composite, but kept constant the TiO2 shell thickness formed around the MWCNTs. A change in the Li-ion storage process from mostly insertion (at SiO2 1 mol%) to entirely pseudocapacitive (at SiO2 9 mol%), was observed. This allowed a better capacity retention at high cycling rates, when the material was tested between 3 and 1 V vs. Li/Li+. Nonetheless, when the potential windows during cycling was increased from 3 to 0.5 V, the specific capacity of the composite modified with 9 mol% of SiO2, vanished at high cycling rates. The thoroughly EIS characterization in the whole potential window (from 3 to 0.5 V) of the tested half cells, evidenced the enlargement of charge transfer resistance; which was associated to highly reactive –OH groups (FTIR and TGA) present in the composite, promoted by the addition of SiO2 in the shell.

P-n heterostructured TiO2/NiO double-shelled hollow spheres for the photocatalytic degradation of papermaking wastewater

P-n heterostructured TiO2/NiO double-shelled hollow spheres were prepared through sol–gel and hydrothermal processes. TiO2/NiO nanomaterials were comprehensively characterized, and the results reveal that a cubic-structured NiO layer is successfully grown on the surface of the anatase TiO2 hollow sphere to achieve a p-n heterostructure. The thickness of TiO2 shell is ∼20 nm, and that of NiO shell is 10–25 nm. Compared with the pure TiO2 hollow spheres, the prepared p-n heterostructures display a considerably higher photocatalytic activity for papermaking wastewater degradation under UV light irradiation. The chemical oxygen demand removal rate of papermaking wastewater reaches 98.1% after 6 h of photodegradation with DSTN2 as the photocatalyst. The enhanced photocatalytic activity is due to the synergetic effects of p-n heterostructures and the large specific surface area of the catalyst; these effects may promote the separation of photogenerated electron–hole pairs.

Complex ZnO-TiO2 Core-Shell Flower-Like Architectures with Enhanced Photocatalytic Performance and Superhydrophilicity without UV Irradiation.

ZnO-TiO2 core-shell photocatalysts of a complex flower-like architecture were synthesized, using a well-controlled sol-gel coating reaction of presynthesized ZnO flower-like structures. The samples were characterized by X-ray diffraction, field emission scanning and transmission electron microscopy, energy-dispersive X-ray spectroscopy, diffuse reflectance UV-vis and attenuated total reflectance-Fourier transform infrared spectroscopy, nitrogen adsorption-desorption measurements, and photoluminescence measurements. Well-defined, core-shell flowers with a wurtzite ZnO core and anatase TiO2 shells, with variable shell thickness, were acquired by appropriately adjusting the ZnO/Ti precursor mass feed ratio in the reaction. Moreover, hollow TiO2 flowers were obtained, and they retained their morphology following the etching of the ZnO core in an acidic solution. The photocatalytic performance of the core-shell and hollow semiconductors was evaluated via the decoloration of a methylene blue dye solution under UV-vis irradiation. The core-shell flowers exhibited a higher decoloration rate, when compared with bare ZnO flowers, TiO2 particles, and hollow TiO2 flowers, and the photoactivity was dependent on the TiO2 shell thickness. This was attributed to the efficient separation of the photogenerated holes and electrons at the ZnO-TiO2 interface. Moreover, the most photoactive core-shell catalyst exhibited excellent reusability and stability for at least three photocatalytic cycles and excellent superhydrophilicity without UV irradiation, which is due to the increased roughness of the flower-like structures.

MIL-125-NH2@TiO2 Core–Shell Particles Produced by a Post-Solvothermal Route for High-Performance Photocatalytic H2 Production

Metal-organic frameworks (MOFs) have proven to be an interesting class of sacrificial precursors of functional inorganic materials for catalysis, energy storage, and conversion applications. However, the controlled synthesis of MOF-derived materials with desirable compositions, structures, and properties still remains a big challenge. Herein, we propose a post-solvothermal route for the outer-to-inner loss of organic linkers from MOF, which is simple, rapid, and controllable and can be operated at temperature much lower than that of the commonly adopted pyrolysis method. By such a strategy, the MIL-125-NH2 particles coated by TiO2 nanosheets were produced, and the thickness of TiO2 shell can be easily tuned. The MIL-125-NH2@TiO2 core-shell particles combine the advantages of highly active TiO2 nanosheets, MIL-125-NH2 photosensitizer, plenty of linker defects and oxygen vacancies, and mesoporous structure, which allows them to be utilized as photocatalysts for the visible-light-driven hydrogen production reaction. It is remarkable that the hydrogen evolution rate by MIL-125-NH2@TiO2 can be enhanced 70 times compared with the pristine MIL-125-NH2. Such a route can be easily applied to the synthesis of different kinds of MOF-derived functional materials.

CuO–TiO2p–n core–shell nanowires: Sensing mechanism and p/n sensing-type transition

The sensing properties and underlying sensing mechanisms of CuO–TiO2p–n type core–shell (C–S) nanowires (NWs) were investigated as a function of the TiO2 shell thickness. An extraordinary p/n transition in the sensing behavior was found to depend on the shell thickness: p-type CuO-core NWs dominate the sensing type up to a shell thickness of 40 nm, likely through a tunneling effect, but for thicker shells, n-type TiO2 shells dominate. In C–S NWs with thin shells that allow gas molecules to interact with the CuO-core NWs, less resistance modulation is developed due to the compensation of both n- and p-type conduction from the two materials. In contrast, in the case of shells that are too thick, partially depleted n-type shells deteriorate the resistance modulation. The results indicate that the shell thickness should be controlled in between these two edge cases to attain optimal sensing capabilities of the CuO–TiO2p–n C–S NWs: thick enough to prevent the interaction of gas molecules with the core NWs, while simultaneously thin enough to achieve high electron depletion.

Synthesis of titania wrapped cadmium sulfide nanorods for photocatalytic hydrogen generation

Herein we report a simplified synthetic approach for a semiconductor photocatalyst (CdS) wrapped with a nanoscale thin-layer of semiconducting material (TiO2) to overcome the instability issues, besides the improved catalytic efficiency. Images of HR-TEM and elemental mapping evidenced the presence of CdS that covered by ultra thin-layer of TiO2 as shell. The UV–vis diffuse reflectance spectra showed red-shift in absorption edge in visible region. The photocatalytic water splitting towards hydrogen production using Na2S/Na2SO4 as sacrificial agent was evaluated under UV–vis and visible light irradiation. The essential variables such as thickness of TiO2 shell, amount of sacrificial agent and solution pH were fine tuned to achieve hydrogen generation of 5791 mL h−1 g−1 of catalyst. The higher efficiency is ascribed to core/shell morphology of CdS/TiO2 system that channelled the excitons to the surface for the red-ox reactions rather than recombination. The catalytic stability result ascertained that the photo-corrosion is greatly suppressed.

A facile coating method to construct uniform porous α-Fe2O3@TiO2 core-shell nanostructures with enhanced solar light photocatalytic activity

A new synthetic approach has been developed to prepareα-Fe2O3@TiO2 core-shell nanostructures at ambient conditions (e.g., in water, ≤100 °C). This approach shows a few unique features, including: short reaction time (a few minutes) for forming core-shell nanostructures, no requirement of high temperature calcinations for generating TiO2 (e.g., at 80–100 °C), tunable TiO2 shell thickness, high yield and good reproducibility. The experimental results show that the α-Fe2O3@TiO2 core-shell nanostructures exhibit enhanced photocatalytic activity compared to the pure TiO2 and pure Fe2O3 in degradation of organic dye molecules with solar light irradiation. This could be attributed to the large surface area of TiO2 nanoparticles for maximum harvesting light adsorption, enhanced visible light absorption, and the effective charge separation at the heterojunction of α-Fe2O3 and TiO2. The findings may open a new strategy to synthesize TiO2-based photocatalysts with enhanced efficiency for environmental remediation applications.

Highly Active Ni2P Catalyst Supported on Core–Shell Structured Al2O3@TiO2 and Its Performance for Benzofuran Hydrodeoxygenation

Highly active Ni2P catalyst supported on Al2O3@TiO2 (core@shell) for hydrodeoxygenation (HDO) of benzofuran (BF) was described. The effect of the TiO2 shell thickness on the structure and HDO properties of Ni2P/Al2O3@TiO2 was studied. The results showed that an appropriate TiO2 shell thickness can effectively suppress the formation of AlPO4 and change the transmission mechanism of Ni2P particles, which is beneficial to the formation of highly dispersed Ni2P particles on the Al2O3 core. The Ni2P/A@T-25 showed the best HDO activity of 95% with oxygen-free products yield of 87% among the as-prepared Ni2P/Al2O3@TiO2 catalysts. As compared with Ni2P/Al2O3 (BF conversion of 78% with oxygen-free products yield of 47%), the BF conversion and yields of oxygen-free products over Ni2P/A@T-25 catalyst were increased by 22% and 85%, respectively.

Na2Ti6O13@TiO2 core-shell nanorods with controllable mesoporous shells and their enhanced photocatalytic performance

In this study, dispersive and free-standing Na2Ti6O13 nanorods with diameter of about 500nm and length of about 10μm were synthesized by the molten salt method. The Na2Ti6O13@TiO2 (denoted as TTO) core-shell nanorods were fabricated by a versatile kinetics controlled coating method. The TiO2 shells were uniform and mesoporous with exposed {101} facets. The thickness of TiO2 shells can be well controlled by the content of Ti(OC4H9)4, ranging from 0nm, 15nm, 60nm to 70nm corresponding to Na2Ti6O13, 0.25-TTO, 0.50-TTO and 0.75-TTO nanorods respectively. The crystalline phases, microstructure, porosity, photoabsorption and photocatalytic performance of all the samples were investigated systematically. The nanoscale heterojunction structure between Na2Ti6O13 and TiO2, reductive TiO2 {101} facets and high aspect ratio Na2Ti6O13 nanorods resulted in the enhanced photocatalytic performance of TTO nanorods. The optimized thickness of TiO2 shells were about 60nm for 0.50-TTO nanorods, which possessed superior BET surface area, optical absorption and photocatalytic performance.

Preparation of a p-n heterojunction BiFeO3@TiO2 photocatalyst with a core–shell structure for visible-light photocatalytic degradation

Magnetically separable bismuth ferrite (BiFeO3) nanoparticles were fabricated by a citrate self-combustion method and coated with titanium dioxide (TiO2) by hydrolysis of titanium butoxide (Ti(OBu)4) to form BiFeO3@TiO2 core–shell nanocomposites with different mass ratios of TiO2 to BiFeO3. The photocatalytic performance of the catalysts was comprehensively investigated via photocatalytic oxidation of methyl violet (MV) under both ultraviolet and visible-light irradiation. The BiFeO3@TiO2 samples exhibited better photocatalytic performance than either BiFeO3 or TiO2 alone, and a BiFeO3@TiO2 sample with a mass ratio of 1:1 and TiO2 shell thickness of 50–100 nm showed the highest photo-oxidation activity of the catalysts. The enhanced photocatalytic activity was ascribed to the formation of a p-n junction of BiFeO3 and TiO2 with high charge separation efficiency as well as strong light absorption ability. Photoelectrochemical Mott–Schottky (MS) measurements revealed that both the charge carrier transportation and donor density of BiFeO3 were markedly enhanced after introduction of TiO2. The mechanism of MV degradation is mainly attributed to hydroxyl radicals and photogenerated electrons based on energy band theory and the formation of an internal electrostatic field. In addition, the unique core–shell structure of BiFeO3@TiO2 also promotes charge transfer at the BiFeO3/TiO2 interface by increasing the contact area between BiFeO3 and TiO2. Finally, the photocatalytic activity of BiFeO3@TiO2 was further confirmed by degradation of other industrial dyes under visible-light irradiation.

Mechanistic insights into TiO2 thickness in Fe3O4@TiO2-GO composites for enrofloxacin photodegradation

Multifunctional Fe3O4@TiO2-GO (FTG) magnetic composites have extensive application potential. However, the effect of TiO2 shell thickness as well as its underlying mechanism remains murky and motivates our study. Herein, FTG composites with the optimized TiO2 shell thickness were synthesized. The characterization results show that the FTG photocatalysts had the advantages of easy magnetic separation, extended light absorption range (>600nm), and efficient charge separation properties. The photocatalytic activity of FTG was performed for photo-degradation of enrofloxacin (ENR) under visible light. The FTG composites with TiO2 layer thickness of 17nm exhibited the highest photocatalytic activity, and significant recycle efficiency. The photocatalytic mechanism, as characterized using electrochemistry, ESR, and in-situ QXAFS analysis, indicates that this optimal TiO2 shell thickness delicately balances the generation and effective transport of electrons, and therefore is optimal for the production of hydroxyl radicals. This study provides new insights into the fabrication of TiO2-based materials and their photocatalytic application.

Experimental and theoretical studies of V2O5@TiO2 core-shell hybrid composites with high gas sensing performance towards ammonia

This study reports a facile but efficient synthesis method for the preparation of titanium oxide coated vanadium oxide (V2O5@TiO2) core-shell nanostructures in water bath at mild temperatures (≤100°C). This method is featured as short reaction time, no requirement of high temperature calcination (>500°C) for TiO2 crystallization, easily tunable TiO2 shell thickness, high yield, and good reproducibility. The as-prepared V2O5@TiO2 nanocomposites can exhibit a large surface area, and good stability. The gas-sensing properties of V2O5@TiO2 core-shell nanoparticles were investigated, it was found that the core-shell materials exhibit superior sensing performance (high response, good selectivity, and short response time) toward ammonia than pure TiO2 or V2O5 sensor materials. Besides experimental studies, theoretical simulations using Density Functional Theory (DFT) method were conducted to fundamentally understand the adsorption behavior of different target gases, such as ammonia, ethanol, methanol, acetone and n-butylamine on the anatase TiO2 (101) surface. The results show that the ammonia is of the lowest adsorption energy (−1.04eV), which can help explain why the V2O5@TiO2 core-shell sensor exhibits excellent response toward ammonia. These findings may bring a new insight into the designing of TiO2-based nanocomposites with diverse functions; meanwhile, provide a better understanding on interactions, at atomic scale, between the TiO2 crystalline surface and the reducing gases.

Enhancing Energy Efficiency in Saccharide–HMF Conversion with Core/shell Structured Microwave Responsive Catalysts

Core/shell structured microwave responsive catalysts with carbon nanotube (CNT) core and acidified TiO2 shell were synthesized in this work for catalytic conversion of saccharide to 5-hydroxymethylfurfural (HMF). The microstructures and surface properties of these hybrid composites were carefully characterized. With such a structure of inner microwave absorber and outer catalyst shell, the heat generated at the core area by microwave radiation can be translated to the shell catalyst directly. Such localized heating allows maximum heat utilization in the reaction and enhances the energy efficiency of the catalytic reaction. The energy efficiency of HMF formation reaches up to 4.2 mol·kJ–1·L–1 by using CNT/TiO2 catalyst, which is six-times higher compared to pure TiO2. The reaction can be completed within 30 min. The effects of TiO2 shell thickness, annealing temperature, catalyst concentration, and microwave power on the saccharide conversion and HMF yield were systematically investigated. These catalysts ...

Substantial enhancement of energy storage capability in polymer nanocomposites by encapsulation of BaTiO3 NWs with variable shell thickness.

Dielectric polymer nanocomposites have received keen interest due to their potential application in energy storage. Nevertheless, the large contrast in dielectric constant between the polymer and nanofillers usually results in a significant decrease of breakdown strength of the nanocomposites, which is unfavorable for enhancing energy storage capability. Herein, BaTiO3 nanowires (NWs) encapsulated by TiO2 shells of variable thickness were utilized to fabricate dielectric polymer nanocomposites. Compared with nanocomposites with bare BaTiO3 NWs, significantly enhanced energy storage capability was achieved for nanocomposites with TiO2 encapsulated BaTiO3 NWs. For instance, an ultrahigh energy density of 9.53 J cm-3 at 440 MV m-1 could be obtained for nanocomposites comprising core-shell structured nanowires, much higher than that of nanocomposites with 5 wt% raw ones (5.60 J cm-3 at 360 MV m-1). The discharged energy density of the proposed nanocomposites with 5 wt% mTiO2@BaTiO3-1 NWs at 440 MV m-1 seems to rival or exceed those of some previously reported nanocomposites (mostly comprising core-shell structured nanofillers). More notably, this study revealed that the energy storage capability of the nanocomposites can be tailored by the TiO2 shell thickness. Finite element simulations were employed to analyze the electric field distribution in the nanocomposites. The enhanced energy storage capability should be mainly attributed to the smoother gradient of dielectric constant between the nanofillers and polymer matrix, which alleviated the electric field concentration and leakage current in the polymer matrix. The methods and results herein offer a feasible approach to construct high-energy-density polymer nanocomposites with core-shell structured nanowires.

Tunable design of yolk–shell ZnFe2O4@RGO@TiO2 microspheres for enhanced high-frequency microwave absorption

Yolk–shell ZnFe2O4@RGO@TiO2 microspheres with a tunable void size and TiO2 shell thickness possess enhanced high-frequency microwave absorption properties.

Dynamics of Electron Injection in SnO2/TiO2 Core/Shell Electrodes for Water-Splitting Dye-Sensitized Photoelectrochemical Cells.

Water-splitting dye-sensitized photoelectrochemical cells (WS-DSPECs) rely on photoinduced charge separation at a dye/semiconductor interface to supply electrons and holes for water splitting. To improve the efficiency of charge separation and reduce charge recombination in these devices, it is possible to use core/shell structures in which photoinduced electron transfer occurs stepwise through a series of progressively more positive acceptor states. Here, we use steady-state emission studies and time-resolved terahertz spectroscopy to follow the dynamics of electron injection from a photoexcited ruthenium polypyridyl dye as a function of the TiO2 shell thickness on SnO2 nanoparticles. Electron injection proceeds directly into the SnO2 core when the thickness of the TiO2 shell is less than 5 Å. For thicker shells, electrons are injected into the TiO2 shell and trapped, and are then released into the SnO2 core on a time scale of hundreds of picoseconds. As the TiO2 shell increases in thickness, the probability of electron trapping in nonmobile states within the shell increases. Conduction band electrons in the TiO2 shell and the SnO2 core can be differentiated on the basis of their mobility. These observations help explain the observation of an optimum shell thickness for core/shell water-splitting electrodes.

Hexagonal Hollow Mesoporous TiO2 Nanoparticles As an Advanced Anode Material for Lithium-Ion Batteries

Recently, TiO2 received tremendous attention due to its low cost, chemical stability, excellent rate performance, proper Li-intercalated potential and environmental friendliness1-3. However, the poor electronic conductivity and relatively low specific capacity lead to the major obstacles for large-scale application in the LIBs. To overcome these deficiencies, a series of efforts have been made to enhance the performance of TiO2 anode. It has been demonstrated that the morphology and nanostructure show significant impacts on the performance of electrochemical performance. However, most of the reported hollow structures have a spherical shape so far, non-spherical hollow structure might exhibit unusual propertioes when used as the anode materials.Hence, we explore the synthesis of the non-spherical hollow structures with favourable shell architectures, and used as the anode materials of LIBs. Here, we introduced an easy scale-up strategy for the fabrication of well-organized hexagonal hollow mesoporous TiO2(HHM-TiO2)materials by a facile, cost-effective template-engaged method at room temperature. We further introduce a conformal carbon coating layer on the hexagonal hollow mesoporous TiO2, and investigate the electrochemical performance. The hollow TiO2 is designed on the basis of the interplay and synergy of controlled hydtolysisi of Ti4+ and accompaning gradual etching of Cd(OH)2. During the process, interfacial reaction between (NH4)2TiF6 and Cd(OH)2 occurred simultaneously,TiO2 layer is deposited on the scaffold of Cd(OH)2 template through accelerated hydrolysis of [TiF6]2 - by consumption of H+.To evaluate the promising use of the TiO2 as an anode material for LIBs, a conformal carbon coating layer was introduced to coat on the porous TiO2 particles by hydrothermal method using glucose as the carbon source.Fig. 1 The morphology characterizations of HHM-TiO2 and HHM-TiO2/C. (a) SEM, (b) TEM and (c) HRTEM of HHM-TiO2, (d) TEM and (e)HRTEM of HHM-TiO2/C, (f) the SEAD pattern of HHM-TiO2 The morphology of the as-prepared HHM-TiO2 and HHM-TiO2/C were characterized by scanning electron microscopy (SEM) and high resolution transmission electron microscopy (HR-TEM.). Fig. 1a indicated that the HHM-TiO2 is consisted of hexagonal particles with the particle-size range from 250 to 350 nm. Meanwhile, the hollow interior can be directly observed from the broken nanoparticle (inset in Fig. 1a) and TEM images (Fig. 1b), while the thickness of TiO2 shell is about 30 nm. A close examination (HRTEM images in Fig. 1c) of the sample reveals a highly porous shell that is consisted of small TiO2 nanoparticles with a size of several nanometers.After introducing the carbon coating layer, the feature of HHM-TiO2/C was analyzed in Fig. 1d-f. The TEM images of HHM-TiO2/C matching well with the pure HHM-TiO2 confirmed that the carbon coating process does not alter the structure of the HHM-TiO2. The selective area electron diffraction (SAED) pattern (Fig. 1f) showed bright diffraction rings indexed to (101), (004), (200), (211), and (204) planes of anatase TiO2, indicating its polycrystalline natureIn summary, a new structure and well-organizedhexagonal hollow mesoporous TiO2 was fabricated by a simple cost-effective method. After wrapping with an elastic carbon matrix, The HHM-TiO2/C electrode showed better rate, with a good rate capability of 175 mA h g-1 at 5 C, 152 mA h g-1 at 10 C and 126 mAh g-1 at 20 C. The higher capacity retention at higher current rates demonstrates a superior rate capability for the HHM-TiO2/C composite. Acknowledgements This work was supported by the Natural Science Foundation of China (21336003, 21333007).