Porous TiO2-coated Magnetic Core-Shell Nanocomposites: Preparation and Enhanced Photocatalytic Activity

The core-shell structured TiO₂/SiO₂@Fe₃O₄ photocatalysts were prepared using Fe₃O₄ as magnetic core, tetraethoxysilane (TEOS) as silica source and tetrabutyl titanate (TBOT) as titanium sources. The as-obtained structure was composed of a SiO₂@Fe₃O₄ core and a porous TiO₂ shell. The diameter of SiO₂@Fe₃O₄ core was about 205 nm with thickness of porous TiO₂ of about 5-6 nm. The 9%TiO₂/6% SiO₂@Fe₃O₄ microspheres possess the highest BET surface area and the BJH pore volume, which are 373.5 m²穏^-1 and 0.28 cm³穏^-1, respectively. The 9%TiO₂/6%SiO₂@Fe₃O₄ photocatalyst exhibited an excellent performance for the degradation of methyl orange and methylene blue dyes. Two different dyes were completely decolorized in 60 min under UV irradiation. The photocatalytic activity and the amount of catalyst were almost not decrease after recycling for 6 times by using external magnetic field.     

Photocatalytic properties of the CeO2-xTiO2 and TiO2-xCeO2 (x = 10, 30, and 50 mol%) heterostructures obtained by a MAH

In this work, CeO₂-TiO₂ heterostructures were submitted to the microwave-assisted hydrothermal (MAH) method at 140°C for 30 minute, and varying the CeO₂ and TiO₂ percentages as 10, 30, and 50 mol%. The heterostructures were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), Brunauer-Emmett-Teller methodology (BET), and UV-Vis diffuse reflectance spectroscopy (UV-Vis). The photocatalytic properties were estimated varying the concentration of methylene blue (MB) dye. The diffractograms indicate the formation of TiO₂ anatase and CeO₂ phases, without the formation of secondary phases. TEM images indicate the formation of nanocubes and nanospheres for CeO₂ and TiO₂, respectively. BET analysis indicates that CeO₂ has the largest surface area (62.80 m².g⁻¹), and TiO₂-10%CeO₂ heterostructure has a low surface area (26.13 m².g⁻¹). The addition of TiO₂ to CeO₂ increases the photocatalytic activity from 32% to 80% for CeO₂ and CeO₂-50%TiO₂, respectively. In contrast, the addition of CeO₂ significantly decreases the photocatalytic activity of TiO₂ from 98.9% to 50% for TiO₂ and TiO₂-50%CeO₂, respectively. Reuse tests showed that the TiO₂-xCeO₂ samples maintain the photocatalytic response in subsequent cycles while the CeO₂-xTiO₂ samples have an increase in the response.     

Low thermal conductivity in porous SiC–SiO2–Al2O3–TiO2 ceramics induced by multiphase thermal resistance

The introduction of multiple heterogeneous interfaces in a ceramic is an efficient way to increase its thermal resistance. Novel porous SiC–SiO₂–Al₂O₃–TiO₂ (SSAT) ceramics were fabricated to achieve multiple heterogeneous interfaces by sintering equal volumes of SiC, SiO₂, Al₂O₃, and TiO₂ compacted powders with polysiloxane as a bonding phase and carbon as a template at 600 °C in air. The porosity could be controlled between 66% and 74% by adjusting the amounts of polysiloxane and the carbon template. The lowest thermal conductivity (0.059 W/(m·K) at 74% porosity) obtained in this study is an order of magnitude lower than those (0.2–1.3 W/(m·K)) of porous monolithic SiC, SiO₂, Al₂O₃, and TiO₂ ceramics at an equivalent porosity. The typical specific compressive strength value of the porous SSAT ceramics at 74% porosity was 3.2 MPa cm³/g.     

Mesoporous TiO2–SiO2 aerogels with hierarchal pore structures

Freestanding blocks of binary oxides, TiO₂–SiO₂ aerogel containing highly ordered mesophase structures were successfully prepared by a new synthesis method involving partial solvent evaporation followed by supercritical extraction and drying. The new method allows the routine preparation of large, crack-free aerogels of high titanium content (i.e., Ti/Si ? 0.75 or up to 50 wt.% Ti), ordered mesopores (i.e., 2–20 nm), large surface area (i.e., 400–900 m² g^?1) and pore volume (i.e., 0.7–2.6 cm³ g^?1). Aerogels with well-ordered mesopores were obtained for Ti/Si atom ratios of 0.04–0.08. The size of ordered mesopore domains decreases with increasing titanium loading, and TS75 aerogels with Ti/Si = 0.75 display discontinuous microdomains of ordered mesoporosity within disordered phases interspersed with crystalline anatase TiO₂. The greater permeability of the TS75 pore network resulted in fifteen times better activity for photocatalytic oxidation of airborne trichloroethylene compared to commercial Degussa P25 TiO₂ and more than twice that TiO₂–SiO₂ aerogel (TS100) of similar titanium loading but with disordered and tortuous pore network.     

Effects of SiO2 addition on TiO2 crystal structure and photocatalytic activity

A series of TiO₂–SiO₂ mixtures – having the following stoichiometry Ti_1?xSi_xO₂, with x = 0, 0.1, 0.3 and 0.5 atoms per formula unit – were prepared by using precursor oxides and fired at three temperatures (900, 1000 and 1200 °C). The modifications in the structure and, consequently, on the photocatalytic activity, induced by the addition of SiO₂ into the TiO₂ powder, were thoroughly investigated by using various analytical techniques: X-ray powder diffraction, electron microscopy (FE-SEM and TEM), XPS, FT-IR, DRS and BET analysis. The results underlined as essentially no solid solution occurs between the two crystalline end-members. Nevertheless, silica addition caused a retarding effect on anatase-to-rutile phase transformation and on the crystallite growth.The photocatalytic activity of the powders was assessed in gas phase and the results were explained by taking into account the anatase and rutile relative amounts in the samples, their crystallite size, the surface hydroxyl groups adsorbed on the photocatalysts and the surface area of the mixtures.     

Fabrication of TiO2 nanowhiskers by the heat treatment of bulk Ti3Si0.9Al0.1C2 in rough vacuum

Rutile TiO₂ nanowhiskers with [0 0 1] growth direction were successfully fabricated by treating bulk Ti₃Si_0.9Al_0.1C₂ solid solution at 900 °C in 10⁴ Pa air. In the initial stage, TiO₂ nanowhiskers are preferentially formed on the side facets of Ti₃Si_0.9Al_0.1C₂ grains due to the rapid diffusion of Ti atoms along the basal planes. With the increase of treating time, a mixed oxide scale of TiO₂, SiO₂ and Al₂O₃ is gradually developed. Consequently, the growth of TiO₂ nanowhiskers is controlled by the diffusion of Ti in the mixed oxide scale. In addition, it is found that the growth rate of TiO₂ nanowhiskers strongly depends on the air pressure and the treating temperature. It diminishes dramatically with the decrease of temperature. However, only TiO₂ nanosheets and large grains can be obtained above 1000 °C. In addition, air pressure around 10⁴ Pa is appropriate for the growth of nanowhiskers.     

Determination of interdiffusion coefficients of Si and Al in Ti3SiC2–Ti3AlC2 diffusion couple at 1373-1673 K

In the diffusion couple of Ti₃SiC₂ and Ti₃AlC₂, only interdiffusion of Si and Al occurred during diffusion treatment process. Based on the concentration profiles of Si and Al measured by electron probe microanalysis (EPMA), the interdiffusion coefficients of Si and Al at 1373-1673 K in Ti₃SiC₂–Ti₃AlC₂ diffusion couple were determined by both the Boltzmann-Matano (B-M) method and the Saucer-Freise (S-F) method. At the position of Matano plane with the composition of Ti₃Al_0.5Si_0.5C₂, the interdiffusion coefficient could be expressed as D_int (m²/s) = 5.6 × 10⁻⁴⋅exp [−246 ± 14 (kJ/mol)/RT]. Based on the two methods, the calculated interdiffusion coefficients increased with increasing temperature, and the magnitudes of their absolute values were on the order of 10^–13-10^–11 m²/s at 1373-1673 K. At 1373-1573 K, the calculated interdiffusion coefficients decreased monotonously with the increase of Si concentration, that is, x_Si/(x_Al + x_Si). But at 1673 K, the variation trend of interdiffusion coefficients with x_Si/(x_Al + x_Si) was no longer monotonous, probably due to the presence of Ti₅Si₃ phase and voids on Ti₃AlC₂ side.     

Evolution of TiOx-SiOx nano-composite during annealing of ultrathin titanium oxide films on Si substrate

This paper discusses the formation of the TiO_x-SiO_x nano-composite phase during annealing of ultrathin titanium oxide films (~27 nm). The amorphous titanium oxide films are deposited on silicon substrates by sputtering. These films are important for high-k dielectrics and sensing applications. Annealing of these films at 750 °C in the O₂ environment (for 15–60 min) resulted in the polycrystalline rutile phase. The films exhibit Raman peaks at 150 cm⁻¹ (B_1g), 435 cm⁻¹ (E_g), and 615 cm⁻¹ (A_1g) confirming the rutile phase. The signature TO (1078 cm⁻¹) and LO (1259 cm⁻¹) infrared active vibrational modes of Si–O–Si bond confirms the presence of silicon-oxide. The X-ray photoelectron spectra of the TiO_x films show multiple peaks corresponding to Ti metal (453.8 eV); Ti⁴⁺ state (458.3 eV (Ti 2p_3/2) and 464 eV (Ti 2p_1/2)); and Ti³⁺ state (456.4 eV (Ti 2p_3/2) and 460.8 eV (Ti 2p_1/2)). The O1s XPS spectra peaks at 530–533 eV can be attributed to Ti–O and Si–O bonds of the TiO_x-SiO_x nano-composite phase in the annealed films. The depth profiling XPS study shows that the top surface of the annealed film is mainly TiO_x and the amount of SiO_x increases with the depth.     

Effect of Ti5Si3 on wear properties of Ti3Si(Al)C2

Near-fully dense Ti₃Si(Al)C₂/Ti₅Si₃ composites were synthesized by in situ hot pressing/solid–liquid reaction process under a pressure of 30 MPa in a flowing Ar atmosphere at 1580 °C for 60 min. Compared to monolithic Ti₃Si(Al)C₂, Ti₃Si(Al)C₂/Ti₅Si₃ composites exhibit higher hardness and improved wear resistance, but a slight loss in flexural strength (about 26% lower than Ti₃Si(Al)C₂ matrix). In addition, Ti₃Si(Al)C₂/Ti₅Si₃ composites maintain a high fracture toughness (K_IC = 5.69–6.79 MPa m^1/2). The Ti₃Si(Al)C₂/30 vol.%Ti₅Si₃ composite shows the highest Vickers hardness (68% higher than that of Ti₃Si(Al)C₂) and best wear resistance (the wear resistance increases by 2 orders of magnitude). The improved properties are mainly ascribed to the contribution of hard Ti₅Si₃ particles, and the strength degradation is mainly due to the lower Young's modulus and strength of Ti₅Si₃.     

Thermochemical stability of Y2Si2O7 in high-temperature water vapor

The thermochemical stability of Y₂Si₂O₇ was assessed in a high-temperature high-velocity water vapor environment to improve the understanding of the mechanisms that lead to SiO₂ depletion. Spark plasma sintered Y₂Si₂O₇ specimens were exposed in a steam-jet furnace at 1000°C and 1200°C for 3-250 hours, steam velocities of 131-174 m/s and at 1 atm H₂O pressure. These exposures resulted in the selective volatilization of SiO₂ to form volatile Si(OH)₄ and porous Y₂SiO₅. Microstructural evolution from fine rectangular pores at short times to larger rounded pores at longer times was observed. Mechanisms contributing to the overall depletion reaction kinetics were evaluated and include the interface reaction to form Y₂SiO₅ and Si(OH)₄ (g), Y₂SiO₅ coarsening, development of tortuosity in the pore network and diffusion of H₂O (g) and Si(OH)₄ (g) through pores by molecular diffusion and/or Knudsen diffusion. SiO₂ depletion was found to follow parabolic volatilization kinetics (k_p = 0.38 µm²/h) at 1200°C indicating the reaction is limited by a diffusion process, most likely the outward diffusion of Si(OH)₄ (g) through pores. Results are utilized to assess the viability of Y₂Si₂O₇ and other rare-earth silicates as environmental barrier coating (EBC) materials for SiC ceramic matrix composites (CMCs).     

High strengthening effects and excellent wear resistance of Ti3Al(Si)C2 solid solutions

The Ti₃Al_1.2−xSi_xC₂ (x = 0, 0.2, 0.4) powders were synthesized from Ti, Al, Si, and TiC powders, and nearly pure Ti₃Al_1.2−xSi_xC₂ bulks were fabricated by the means of two-time hot-pressing method. Significant strengthening effect in bulks was found after the addition of 0.2 Si and 0.4 Si to form Ti₃Al(Si)C₂ solid solutions. The flexural strengths of Ti₃AlSi_0.2C₂ and Ti₃Al_0.8Si_0.4C₂ were 485 and 554 MPa, 14% and 30% larger than the strength of Ti₃AlC₂, respectively. The Vickers hardness of these compounds were separately, 6.95 and 7.57 GPa, representing the enhancements of 37% and 49% over those of Ti₃AlC₂. The tribological behavior was studied by dry-sliding method with a S45C steel at the sliding speed of 30 m/s and the normal load of 20-80 N. The results showed that after incorporating different contents of Si, the friction coefficient was between 0.22 and 0.30, correspondingly lower wear rate was 3.19-2.61 × 10⁻⁶ mm³/Nm. These excellent tribological performances were attributed to the presence of continuous self-generated oxidized films during tribological examination. Finally, the phase compositions and microhardness of the oxidized films were analyzed and characterized.     

Photocatalytic decomposition of benzene with plasma sprayed TiO2-based coatings on foamed aluminum

Plasma spraying technique was used to deposit thin TiO₂-based photocatalytic coatings on foamed aluminum. Before plasma spraying, the composites of nano-TiO₂ powder (P25) and nano-ZnO/CeO₂/SnO₂ powders were agglomerated into microsized powders by spray-drying process. X-ray diffraction (XRD), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and photocatalytic activity evaluation by the decomposition of gas-phase benzene (C₆H₆) were applied to characterize the starting powders and the coatings, respectively. The results showed that all the three plasma sprayed TiO₂-based coatings were the mixture phases of anatase and rutile. On the splats’ surfaces of the as-sprayed coatings, fine nano-crystalline particles were observed. However, grain growth occurred on the surface of plasma sprayed 90%TiO₂–10%ZnO coating. The XPS spectra revealed that the Ti, Zn, Ce and Sn elements existed on the surfaces of plasma sprayed TiO₂-based coatings as the chemical states of Ti⁴⁺, Zn²⁺, Ce⁴⁺ and Sn⁴⁺, respectively, whilst, the oxygen element was composed of three kinds of chemical states, i.e. crystal lattice oxygen, hydroxyl oxygen and physical-adsorbed oxygen. It was found that plasma sprayed 90%TiO₂–10%CeO₂ coating and 90%TiO₂–10%SnO₂ coating exhibited similar photocatalytic activity, which was higher than that of plasma sprayed 90%TiO₂–10%ZnO coating. The photocatalytic activity is not only dependent on the anatase content but also on the surface morphology and the hydroxyl content formed on the surface of plasma sprayed TiO₂-based coatings as well as the additive character.     

Zn2+ doped TiO2/C with enhanced sodium-ion storage properties

To improve the performance of anatase TiO₂ as an anode material for sodium-ion batteries, Zn²⁺-doped TiO₂/C composites are synthesized by a co-precipitation method. The results of XRD, EPR and XPS demonstrate that Zn²⁺ occupies at the Ti⁴⁺ site of TiO₂ to form a solid-solution, resulting in an expansion of lattice and an increase of Ti³⁺ content. The expansion of lattice can enhance the stability of the crystal structure of TiO₂. The increase of Ti³⁺ content can improve the conductivity of TiO₂. Therefore, Ti_0.94Zn_0.06O₂/C delivers a reversible capacity of 160 mA h g⁻¹ with a capacity retention of 96% after 100 cycles at 5 C. Even charged/discharged at 10 C, this sample still exhibits a reversible capacity of 117 mA h g⁻¹, comparing to 86 mA h g⁻¹ for TiO₂/C. The enhanced electrochemical performances can be ascribed to the improvement of the conductivity and the structural stability of TiO₂ due to Zn²⁺-doping. Therefore, Ti_0.94Zn_0.06O₂/C is an attractive anode material of sodium-ion batteries.     

Direct Solvothermal Formation of Nanocrystalline TiO2 on Porous SiO2 Adsorbent and Photocatalytic Removal of Nitrogen Oxides in Air over TiO2–SiO2 Composites

Solvothermal decomposition of titanium(IV) tert-butoxide (TTB) in toluene at 573 K in the presence of silica gel (SiO₂) with continuous stirring yielded a titanium(IV) oxide (TiO₂)–SiO₂ composite in which agglomerates of nanocrystalline TiO₂ were deposited on the surfaces of SiO₂ particles. Various TiO₂–SiO₂ composites having different TiO₂ contents can be synthesized by changing the ratio of TTB and SiO₂, and the composites had large surface areas corresponding to porous properties of SiO₂. These TiO₂–SiO₂ composites were used for photocatalytic removal of nitrogen oxides in air and their photocatalytic performances were compared with those of other TiO₂–SiO₂ samples prepared by different methods. Solvothermally synthesized 74 wt.%TiO₂–SiO₂ composite exhibited excellent photocatalytic performance (almost stoichiometric removal of NO _x (98%) and very low NO₂ release (0.3%)) attributable to high photocatalytic activity of TiO₂ and high adsorption property of SiO₂. Lesser performance of 74 wt.%TiO₂–SiO₂ composites prepared by other methods suggested that pore-mouth plugging of SiO₂ by TiO₂ and lower level of mixing of TiO₂ and SiO₂ decreased photocatalytic performance of the composites.     

Variable thermochemical stability of RE2Si2O7 (RE = Sc,Nd, Er,Yb, or Lu) in high-temperature high-velocity steam

Five rare-earth (RE) disilicates (RE₂Si₂O₇, RE = Sc, Nd, Er, Yb, or Lu) were synthesized and exposed to high-velocity steam (up to 235 m/s) for 125 hours at 1400°C. Water vapor reaction products, mass loss, average reaction depths, and product phase microstructural evolution were analyzed for each material after exposure. Similar to steam testing results in the literature, RE₂Si₂O₇ (RE = Er, Yb, Lu) underwent silica depletion producing gaseous silicon hydroxide species, RE₂SiO₅, and RE₂O₃ product phases. Sc₂Si₂O₇ reacted with high-velocity steam to produce only a Sc₂O₃ product layer with no stable Sc₂SiO₅ phase detected by X-ray diffraction or microscopy techniques. Further, Nd₂Si₂O₇ rapidly reacted with steam to produce with no Nd₂SiO₅ or Nd₂O₃ reaction products. All RE₂Si₂O₇ that produced a silicate reaction product (RE = Nd, Er, Yb, Lu) showed densification of the product phase at steam velocities above 150 m/s that resulted in enhanced resistance. The results presented in this work demonstrate that rare-earth silicates show diverse steam reaction products, reaction product microstructures, and total reaction depths after high-temperature high-velocity steam exposure. Of the materials in this study, RE₂Si₂O₇ (RE = Yb, Lu) were most stable in high-temperature high-velocity steam, making them most desirable as environmental barrier coating candidates.     

A direct electrochemical route from oxides to Ti-Si intermetallics

The titanium silicide intermetallics have been directly prepared from the mixture of titanium oxide (TiO₂) and silicon oxide (SiO₂) powder by using the solid-oxygen-ion-conducting membrane (SOM) electrolysis process. The electrochemical process was carried out in a molten flux CaCl₂ at 950 °C with a potential of 3.5-4.0 V. The effects of the stoichiometry of the initial mixture on the electrolysis characteristics and the final product compositions were investigated. It has been found that the molar ratio of TiO₂:SiO₂ dominates the composition of final products. A single-phase silicide Ti₅Si₃ intermetallic was obtained when the TiO₂:SiO₂ molar ratio is 5:3; the TiSi was identified as the dominant phase with a minor amount of TiSi₂ at TiO₂:SiO₂ molar ratio 1:1; three silicide phases, Ti₅Si₄, Ti₅Si₃ and TiSi, were found coexisting in the final product produced from TiO₂-SiO₂ mixture of molar ratio 5:4; the product of electrolysis consisted of the compound Ti₅Si₃ and the pure metal Ti as TiO₂:SiO₂ molar ratio equals to 3:1; and two silicide phases, TiSi and TiSi₂, are formed as TiO₂:SiO₂ molar ratio equals to 1:2. The preliminary experimental results suggest that the electro-deoxidization process is fast and the current efficiency reached 75%.     

Preparation of TiO2-pillared montmorillonite as photocatalyst Part I. Microwave calcination, characterisation, and adsorption of a textile azo dye

Two photocatalysts based on TiO₂-pillared intercalated montmorillonite have been prepared by microwave for 10 min at 700 W or by furnace heating at 673 K. Montmorillonite pillaring with TiO₂ increased the basal spacing to 14.7 Å (conventional heating) and 17.6 Å (microwave heating). XRD patterns of both materials showed the presence of 100% anatase with a slightly higher rate of crystallinity obtained through microwave calcination than by conventional heating at 673 K. The BET specific surface area of the microwave prepared photocatalyst (151 m² g^− 1) was 3 fold higher than those of the Degussa TiO₂ P25. At pH = 5.8, the maximum adsorption capacity of Solophenyl red 3BL (a textile azo dye) on the TiO₂-pillared montmorillonite calcined by microwave was 185 mg g^− 1, whereas it was 1.4 and 3 fold lower on the TiO₂-pillared montmorillonite calcined at 673 K, and on the Degussa TiO₂ P25 respectively. The influence of pH on the adsorption of the dye depended on the pH_ZPC of the pillared montmorillonites.     

Evaluation of the Mn(II) adsorption potential of SiO2 obtained by different wet chemical methods

This paper describes the development of SiO₂ by 2 different wet chemical methods: polymeric precursor (PP) and sol-gel (SG). These samples were used as adsorbents of Mn(II) metal ions. Physicochemical characteristics of the 2 adsorbents were established, while zeta potential, Scanning Electron Microscopy, and Brunauer-Emmett-Teller (BET) surface area methods were further employed for characterization. Efficiencies of the prepared adsorbents in the adsorption of Mn(II) from aqueous solutions were investigated. The BET surface areas of the prepared adsorbent were 171 and 7 m² g⁻¹ for SiO₂ PP and SiO₂ SG, respectively. Optimal adsorption occurred at pH 8.5, 5g L⁻¹ of adsorbent concentration, and 90 minutes of contact time for both adsorbents. The Langmuir and Freundlich isotherms models fitted the experimental data of SiO₂ PP and SiO₂ SG, respectively, and SiO₂ PP showed the highest adsorption capacity due, probably, to its greater specific area.     

Solid acidities of SiO2–TiO2/montmorillonite composites synthesized under different pH conditions

SiO₂–TiO₂/montmorillonite composites were prepared under acidic, neutral and basic conditions and the solid acidity of the resulting composites were determined. All the SiO₂/TiO₂ ratio of the colloidal particles was set at 10 but the resulting SiO₂/TiO₂ ratios were significantly richer in TiO₂. The XRD patterns of the acidic composite showed expanding and broadening of the (001) reflection by intercalation of colloidal SiO₂–TiO₂ particles, but the neutral and basic composites showed only broadening of the reflections and no intercalation. The specific surface areas of the acidic, neutral and basic composites (375, 237 and 247 m²/g, respectively) were much larger than of montmorillonite (6 m²/g). The average pore sizes were about 4, 15 and 50 nm, and the amounts of solid acidic sites measured by the NH₃-TPD were 178, 95 and 86 µmol/g for the acidic, neutral and basic composites, respectively. The solid acid amount of the acidic composite was twice that of a commercial catalyst, K-10, (85 µmol/g) and much higher than the guest phase SiO₂–TiO₂ gel (16 µmol/g) or the host phase montmorillonite (6 µmol/g). The TPD peak temperatures reflect the acid strength, and were similar in all the samples, ranging from 175° to 200 °C.     

Grain-boundary engineering inducing thermal stability,low dielectric loss and high energy storage in Ta+Ho co-doped TiO2 ceramics

How to achieve a giant dielectric constant and high energy storage density at the same time has been the problem to be solved for donor-acceptor co-doped TiO₂ ceramics. In this work, (Ho_0.5Ta_0.5)_0.01Ti_0·99O₂ - x SiO₂, where x = 0, 1, 3, 5 and 7 wt% (HTTO - x wt% SiO₂), nanocomposites were prepared via a conventional mixed oxide technique. Significantly, the HTTO - 5 wt% SiO₂ composite ceramic exhibits a low dielectric loss (tanδ ～ 0.012) and an ultrahigh permittivity (ε_r ～ 1.29 × 10⁴) at 1 kHz. Also, excellent energy storage property with a high breakdown field strength (E_b ～1.86 kV/cm) and energy storage density (η ～ 1.97 mJ/cm³) was obtained in HTTO - 5 wt% SiO₂ ceramic. Besides, the enhancement of E_b is attributed to the finer grains and the presence of SiO₂ blocking layers in the grain boundaries, which hinder the long-range motion of electrons. It can be concluded that the CP and high energy storage properties arise from the combined contribution of enhanced grain boundary effects and electron-pinning type of defect dipole (EPDD) effects. This study not only proposes an effective method improving E_b, but also offers a new routine for how to simultaneously achieve CP and high η in TiO₂ dielectric materials.