One-pot synthesis of bifunctionalized TiO<Subscript>2</Subscript> mesoporous photocatalyst with visible light response

A series of Fe-doped SH/TiO₂ mesoporous photocatalysts have been firstly prepared by one-pot method using P123 as structure-directing agent. This bifunctionalized mesoporous TiO₂ possesses perfect anatase crystal structure and high surface area. The surface area of Fe-doped SH/TiO₂ mesoporous material is 4 times higher than that of P25. Based on the EPR results, it was found that trivalent Fe ions exist at low spin state and substitutes a part of Ti⁴⁺ ions into TiO₂ lattice. Fe-dropping in TiO₂ extends the adsorption band side of the resulting material to about 600 nm. Much high photocatalytic activity in the degradation of phenanthrene was obtained on the bifunctionalized mesoporous TiO₂ under visible light irradiation (λ > 420 nm), which is 6 times higher than that of pristine mesoporous TiO₂. The enhancement in the photocatalytic activity of bifunctionalized TiO₂ is ascribed to the extended absorption to visible light and strong interaction between SH-groups and PHE molecules.     

Preparation and Characterization of Mesoporous MoO<Subscript>3</Subscript>/TiO<Subscript>2</Subscript> Composite with High Surface Area by Self-Supporting and Ammonia Method

Abstract  

A mesoporous MoO₃/TiO₂ composite was prepared from titanate derivative by consecutive self-supporting and ammonia method. All samples were characterized by X-ray Diffraction, N₂ adsorption–desorption, Raman Spectra and Field-Emission Scanning Electron Microscopy. The results showed that mesoporous MoO₃/TiO₂ composite had a higher surface area (173 m²/g) and a better MoO₃ dispersion than that prepared by traditional impregnation (90 m²/g). As for hydrodesulfurization tests, mesoporous MoO₃/TiO₂ composite in this case presented a better catalytic performance, attributed to its high surface area and good dispersion of MoO₃. It can be found that self-supporting played a key role in preparing mesoporous MoO₃/TiO₂ composite with high surface area. Additionally, aqueous ammonia could effectively dissolve excess MoO₃, which helped to obtain mesoporous MoO₃/TiO₂ composite with better dispersion of MoO₃.     

Effects of templating surfactant concentrations on the mesostructure of ordered mesoporous anatase TiO2 by an evaporation-induced self-assembly method

We prepared ordered hexagonal mesoporous TiO₂ by an evaporation-induced self-assembly (EISA) method using Pluronic P123 and tetrabutyl orthotitanate (Ti(OBuⁿ)₄, TBOT) as the templating agent and the titanium source, respectively. The main purpose of this study was to elucidate the effects of surfactant concentrations on the pore arrangement, pore size, specific surface area and structure of mesoporous TiO₂ by the EISA method. The mesostructures of mesoporous TiO₂ were characterized with X-ray diffraction (XRD), nitrogen adsorption/desorption isotherms, and transmission electron microscopy (TEM). By varying the concentration of the block copolymer, mesoporous TiO₂ of various pore sizes and pore ordering were prepared. Because the mesostructure is governed by the concentration of P123 surfactant at gelation of the solution, a higher P123/TBOT mole ratio favored the formation of highly ordered mesoporous TiO₂ with a maximum pore volume of 0.26 cm³/g, a high specific surface area of 244 m²/g, and a BJH average pore size of 4.7 nm.     

Al-doped TiO<Subscript>2</Subscript> mesoporous materials: synthesis and photodegradation properties

Aluminium-doped TiO₂ mesoporous material was successfully fabricated by solid-state reaction with cetyltrimethylammonium bromide as a template agent and tetrabutyl orthotitanate as a precursor. The characteristic results from low-angle and wide-angle X-ray diffraction, high resolution transmission electron microscopy and energy dispersive spectroscopy, N₂ absorption–desorption, Fourier transform infrared spectroscopy, Raman spectroscopy, ultraviolet visible light spectroscopy and X-ray photoelectron spectroscopy (XPS) clearly showed that the mesoporous architecture of aluminium-doped TiO₂ was composed of crystal wall and micro-/mesopore formed gradually by the mesopore degradation of anatase TiO₂, and aluminium had been doped into the framework of anatase TiO₂. The mesoporous Al-doped TiO₂ material, not only possessed high thermal stability hexahedral mesostructure, large BET surface area and narrow distribution of pore size, but also showed excellent photodegradation behavior for Congo Red. Furthermore the medium UV–Vis absorption peak of mesoporous aluminium-doped TiO₂ in the range 210–370 nm was the absorption peak of aluminium oxide nanoparticles locating the extraframework of TiO₂. A small quantity of aluminium doped into anatase TiO₂ could obviously improve photodegradation activity, and the photodegradation activity of aluminium-doped TiO₂ was higher than that of pure TiO₂.     

Direct Biomass Fuel Cell (BMFC) with Anode/Catalyst Comprising a Nanocomposite of a Mesoporous n-Semiconductor Film and a Metal Thin Layer: A New Concept of Catalyst Design

Abstract  

We designed an efficient direct biomass fuel cell (BMFC) anode and prepared a nanocomposite [base electrode/mesoporous n-semiconductor (SC) thin film/metal thin layer]. A Pt thin layer was photodeposited onto a mesoporous 20-μm thick TiO₂ thin film having a roughness factor of 2000, which was coated on an F-doped tin oxide/glass base electrode (FTO). This anode/catalyst nanocomposite was efficient at decomposing aqueous solutions of glucose and other biomass-related compounds in combination with an O₂-reducing cathode the other side of which was exposed to ambient air. The nanocomposite exhibited sharp optimum conditions at the atomic ratio of Pt/Ti = 0.33 in the BMFC, generating high electrical power of 2 mW cm⁻² without any light irradiation or bias potential when using a 1 M glucose aqueous solution. This output power is 20 times as large as that generated by a mesoporous TiO₂ film anode under UV-light (18 mW cm⁻²) irradiation. At this ratio, the coated Pt specifically exhibited metallic luster, and its average Pt thickness on the mesoporous TiO₂ nanostructure was calculated to be 0.40 nm. The high BMFC activity was interpreted by the simultaneous Schottky-junction/Ohmic contact nature of the nanocomposite. Other biomass compounds such as sucrose, ethanol and polysaccharides were also effective as direct fuels for the BMFC. Immediately after soaking this composite anode without a cathode in a glucose aqueous solution, continuous evolution of H₂ bubbles was observed from the anode surface. The electrical power generation and H₂ production are easily changed by connecting and disconnecting a cathode, respectively. Based on a simple design and calculation, the present system with glucose fuel has the potential to construct a module stack of 2 kW m⁻³. Simultaneous material/energy circulation by using the BMFC with biomass and its waste fuel is proposed for application in future social systems.     

A VOx/meso-TiO2 catalyst for methanol oxidation to dimethoxymethane

Mesoporous TiO₂ was prepared by simply controlling the hydrolysis of Ti(OBu)₄ with the help of acetic acid. The mesoporous TiO₂ had a well-crystallized anatase phase and a high surface area of 290 m² g⁻¹ with a pore size of about 4 nm. The anatase phase and the mesoporous structure were maintained in the VO_x/TiO₂ catalyst with a monolayer dispersion of V₂O₅, however, the surface area decreased to 126 m² g⁻¹. The catalyst was highly active and selective for methanol oxidation, giving about 55% conversion of methanol and 85% selectivity to dimethoxymethane at 423 K.     

Efficient Photocatalytic Decomposition of Glucose,Starch, and Cellulose to CO<Subscript>2</Subscript> Using a Mesoporous Semiconductor Thin Film

Abstract  

UV light-activated highly efficient photocatalytic decomposition of aqueous glucose and polysaccharides (starch and cellulose) to CO₂ was successfully achieved by using a mesoporous TiO₂ thin film coated on a fluorine-doped transparent conductive glass (FTO). The external quantum efficiency (η) of 0.08 (=8%) was obtained for glucose photodecomposition at neutral pH based on the total incident UV light, and the internal quantum efficiency (η′) was 8 (=800%) based on the photon that was effective for activating the reactant, demonstrating that the major decomposition mechanism is dark auto-oxidation of the activated reactant by O₂. Glucose gave η′ values of 19 at pH 12 and 25 at pH 2 demonstrating that when a glucose molecule was once activated by one photon, the molecule can undergo auto-oxidative decomposition to CO₂ at these pH under dark. Water-soluble starch was also photodecomposed completely to CO₂ with estimated η′ value of 8.6. Water-soluble carboxymethyl cellulose (CMC) also underwent decomposition to CO₂ with similar efficiency of η′ = 5. Solid state cellulose powders could be photodecomposed to CO₂ by sandwiching them between FTO-coated TiO₂ thin films.     

Intense Red Photoluminescence Emission of Sol–Gel‐Derived Nanocrystalline Mg2TiO4 Thin Films

In this work, undoped Mg₂TiO₄ thin films were fabricated on p‐type Si(111) substrates by the sol–gel method, and the red photoluminescence (PL) of the films is introduced and discussed. According to the experimental results, the red emission appears when the films have been thermally treated at higher temperatures, which have a long range and well‐organized crystalline arrangement. Furthermore, to have better realization of the red emission mechanism of Mg₂TiO₄ films, the optical band gap of Mg₂TiO₄ (E_g^Mg2TiO4) was estimated at ~3.7 eV; furthermore, 325 nm (corresponding energy, hν = 3.82 eV > E_g^Mg2TiO4) and 633 nm (corresponding energy, hν = 1.96 eV < E_g^Mg2TiO4) excited light sources were used to clarify the position of the defect levels. In addition, the influence of annealing atmospheres (O₂, air, and vacuum) on the red emission of our samples is also discussed. A significant variety of red emissions can be found between these annealing conditions: the red emission can be effectively enhanced by O₂ annealing, but weakened by vacuum annealing. Results reveal that the red emission of Mg₂TiO₄ thin films may be highly dependent on the completeness of the O–X–O (X = Mg, Ti) bonds.     

Low-temperature fabrication of TiO<Subscript>2</Subscript> film on flexible substrate by atmospheric roll-to-roll CVD

Titanium dioxide (TiO₂) thin film was fabricated using titanium isopropoxide as a precursor through an atmospheric low-temperature roll-to-roll chemical vapor deposition method. TiO₂ was deposited on the PET substrate in the temperature range of room temperature to 100°C, and the working pressure was 740 Torr. The surface morphology of TiO₂ thin film was analyzed by field emission scanning electron microscopy and a 2D surface profiler. The results revealed that the growth rate of TiO₂ film was 31 nm/min at 100°C, and it also showed that the surface is uniform and smooth. Moreover, the lowest root mean square roughness (R _q) value of 1.87 nm was obtained for TiO₂ film prepared at 100°C. The composition of TiO₂ film was confirmed by X-ray photoelectron spectroscopy (XPS) analysis. The film showed very good chemical and optical properties while increasing the substrate deposition temperature. The UV–Vis spectroscopy analysis revealed that TiO₂ films exhibited excellent optical transmittance, more than 91% observed in the visible region.     

Enhanced photoelectric efficiency by surface modification of TiO<Subscript>2</Subscript> thin film using various acidic species

This study examined the photoelectric conversion efficiency of the dye-sensitized solar cell (DSSC) when the surface of a nanometer-sized TiO₂ film, which was prepared using the solvothermal method, was modified by five acid compounds. The TiO₂ film exhibited an anatase structure with an average particle size in the range of 10–15 nm, and the maximum absorption band was shown in the UV-visible spectrum around 360 nm. The surface colors of the carboxylic acid-modified TiO₂ films were changed to light or dark with differing energy conversion efficiencies. Particularly, the conversion efficiency was considerably enhanced from approximately 6.25% for the non-modified TiO₂ film to approximately 7.50% for the film treated by acetic acid of 1.0 mole, with the N719 dye under 100 mW/cm² of simulated sunlight. FT-IR analysis of the films after N719 dye adsorption confirmed that the IR spectrum of the modified TiO₂ showed a sharp and strong band at 500 cm⁻¹, which was assigned to a metal-O bond, due to the formation of a new Ti-O bond between the O of COO⁻ and the Ti atom, which was relatively weaker in the non-modified TiO₂. Furthermore, these results were in agreement with an electrostatic force microscopy (EFM) study showing that the electrons were transferred rapidly to the surface of the acetic acid-modified TiO₂ film, compared with that on the nonmodified TiO₂ film.     

Chemical and electrochemical characterization of TiO<Subscript>2</Subscript>/Al<Subscript>2</Subscript>O<Subscript>3</Subscript> atomic layer depositions on AZ-31 magnesium alloy

In this study, innovative TiO₂/Al₂O₃ mono/multilayers were applied by atomic layer depositions (ALD) on ASTM-AZ-31 magnesium/aluminum alloy to enhance its well-known scarce corrosion resistance. Four different configurations of ALD layers were tested: single TiO₂ layer, single Al₂O₃ layer, Al₂O₃/TiO₂ bilayer and Al₂O₃/TiO₂/Al₂O₃/TiO₂ multilayer deposited using Al[(CH₃)]₃ (trimethylaluminum, TMA), and TiCl₄ and H₂O precursors. All depositions were performed at 120°C to obtain an amorphous-like structure of both oxide layers. The four coatings were then investigated using different techniques, such as scanning electron microscope (SEM), stylus profilometer, glow discharge optical emission spectrometry (GDOES) and polarization curves in 0.05-M NaCl solution. The thickness of all the coatings was around 100 nm. The layers compositions were successfully investigated by the GDOES technique, although obtained data seem to be affected by substrate roughness and differences in sputtering rates between ceramic oxides and metallic magnesium alloy. Corrosion resistance showed to be strongly enhanced by the nanometric coatings, giving lower corrosion current densities in 0.05-M NaCl media with respect to the uncoated substrate (from 10⁻⁴ to 10⁻⁶ A/cm² for the single layers and from 10⁻⁴ to 10⁻⁸ A/cm² for the bi- and multilayers). All polarization curves on coated samples also showed a passive region, wider for the bi-layer (from −0.58 to −0.43 V with respect to Ag/AgCl) and multilayer (from −0.53 to −0.38 V with respect to Ag/AgCl) structures.     

Microstructure and electric properties of (Na0.85K0.15)0.5Bi0.5TiO3 composited films with alternative TiO2 layers

In this work, in order to investigate the effect of TiO₂ layer on the microstructure and piezoelectric properties of (Na_0.85K_0.15)_0.5Bi_0.5TiO₃ (NKBT) thin films, TiO₂ layer was inserted at the interface between the NKBT thin film and substrate and on both sides of the NKBT, i.e., at the interface and on the top of the NKBT thin film. NKBT composited films with alternative TiO₂ layer were deposited on Pt/Ti/SiO₂/Si substrate by aqueous sol‐gel method. X‐ray diffraction observation found that the degree of (100) preferred orientation strengthened with TiO₂ layers added, especially on both sides of NKBT thin film. The TiO₂/NKBT/TiO₂ composited film with both TiO₂ layer of 40 nm thickness exhibited a remnant polarization value P_r of 22.6 μc/cm³ and effective piezoelectric coefficient of approximate 77 pm/V, which are much larger than that of the single‐layered NKBT thin film with P_r value of 13.7 μc/cm³ and of 56 pm/V, respectively. According to the investigation of the temperature‐dependent ferroelectric property, it was found that the P_r gradually increased, and in the meantime the coercive voltage gradually moved to higher voltage with testing temperature varied from 20 to ?150°C. Besides, applied voltage dependence of leakage current density measurement indicated that the TiO₂ layer would effectively lower the leakage current of the films, and the TiO₂/NKBT/TiO₂ composited film both TiO₂ layer of 40 nm exhibited the lowest leakage current.     

The role of TiO<Subscript>2</Subscript> layers deposited on YSZ on the electrochemical promotion of C<Subscript>2</Subscript>H<Subscript>4</Subscript> oxidation on Pt

The electrochemical promotion of Pt/YSZ and Pt/TiO₂/YSZ catalyst-electrodes has been investigated for the model reaction of C₂H₄ oxidation in an atmospheric pressure single chamber reactor, under oxygen excess between 280 and 375 °C. It has been found that the presence of a dispersed TiO₂ thin layer between the catalyst electrode and the solid electrolyte (YSZ), results in a significant increase of the magnitude of the electrochemical promotion of catalysis (EPOC) effect. The rate enhancement ratio upon current application and the faradaic efficiency values, were found to be a factor of 2.5 and 4 respectively, higher than those in absence of TiO₂. This significantly enhanced EPOC effect via the addition of TiO₂ suggests that the presence of the porous TiO₂ layer enhances the transport of promoting O²⁻ species onto the Pt catalyst surface. This enhancement may be partly due to morphological factors, such as increased Pt dispersion and three-phase-boundary length in presence of the TiO₂ porous layer, but appears to be mainly caused by the mixed ionic-electronic conductivity of the TiO₂ layer which results to enhanced O²⁻ transport to the Pt surface via a self-driven electrochemical promotion O²⁻ transport mechanism.     

Surface modified nanostructured-TiO<Subscript>2</Subscript> thin films for removal of Congo red

We synthesized nanostructured TiO₂ thin films by the modified sol-gel template method using the polyethylene glycol as filler media. The TiO₂ surface modification for both the thin films, i.e., template and non-template, was done with the ascorbic acid. All the four thin film samples, S1 (TiO₂ (non-template), TiO₂ (template), S3 (S1 modified with ascorbic acid) and S4 (S2 modified with ascorbic acid), were characterized by various analytical methods. Phase evaluation was monitored by the X-Ray diffraction analysis. Moreover, the thin films particle sizes were obtained to be 22.32, 21.20, 14.52 and 16.77 nm, respectively for the samples S1, S2, S3 and S4. The changes in particle size and morphology due to the PEG and ascorbic acid were determined by scanning electron microscopy (SEM). Similarly, thermal gravimetric (TG) and differential scanning calorimetry (DSC) were performed to determine the decomposition behavior of organic compound present in the solid samples. The functional groups were determined by infrared (IR) analysis. The photocatalytic efficiency, as a reference of Congo red, was conducted using all the four samples of TiO₂ thin films. Complete photocatalytic degradation of Congo red was achieved by these samples within 130, 80, 40 and 30 mins of UV illumination.     

Mesoporous semiconducting oxides for gas sensor application

A fabrication procedure of thermally stable mesoporous SnO₂ and TiO₂ powders has been overviewed along with their gas-sensing properties. Treatment of an as-prepared composite material of a supramolecule surfactant and SnO₂, i.e. a self-assembly of the surfactant fringed with a SnO₂ thin wall, with phosphoric acid enabled us to fabricate thermally stable ordered mesoporous SnO₂ powder having a d₁₀₀ value of 3.2 nm, a crystallite size of 2.0 nm and a large specific surface area of 305 m² g⁻¹ even after calcination at 600 °C for 5 h. A thick film sensor fabricated with the ordered mesoporous SnO₂ powder exhibited higher sensing performance than that fabricated with SnO₂ powder prepared by a conventional method and therefore having a lower specific surface area. Surface modification of the conventional SnO₂ powder with a mesoporous SnO₂ layer was also found to be effective for improving the sensing properties. Mesoporous TiO₂ powder could be prepared by employing a modified sol-gel method with Ti(NO₃)₄ and polyethylene glycol having different molecular weights. Higher sensitivity was achieved with a disc-type sensor fabricated with mesoporous TiO₂ powder, in comparison with one fabricated with commercially available TiO₂ powder in the same form, but its sensing properties needed to be further modified.     

Investigation of N<Subscript>2</Subscript>-fixation on polyaniline electrodes in methanol by electrochemical impedance spectroscopy

The ac response of polyaniline thin films on platinum electrodes was measured at different dc potentials during the N₂-fixation in methanol + LiClO₄ electrolyte with 0.03 mol L⁻¹ H₂SO₄ for the first time. The optimum film thickness was found to be 1.5 μm, N₂-pressure 50 bar and an optimum electrolysis potential of −0.12 V (NHE). The diffusion coefficients for N₂ into the polymer film was found to be (5 ± 2)×10⁻⁹ cm² s⁻¹.     

Functionalized Mesoporous SBA-15 with CeF<Subscript>3</Subscript>: Eu<Superscript>3+</Superscript> Nanoparticle by Three Different Methods: Synthesis,Characterization, and Photoluminescence

Luminescence functionalization of the ordered mesoporous SBA-15 silica is realized by depositing a CeF₃: Eu³⁺ phosphor layer on its surface (denoted as CeF₃: Eu³⁺/SBA-15/IS, CeF₃: Eu³⁺/SBA-15/SI and CeF₃: Eu³⁺/SBA-15/SS) using three different methods, which are reaction in situ (I-S), solution impregnation (S-I) and solid phase grinding synthesis (S-S), respectively. The structure, morphology, porosity, and optical properties of the materials are well characterized by X-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy, N₂ adsorption, and photoluminescence spectra. These materials all have high surface area, uniformity in the mesostructure and crystallinity. As expected, the pore volume, surface area, and pore size of SBA-15 decrease in sequence after deposition of the CeF₃: Eu³⁺ nanophosphors. Furthermore, the efficient energy transfer in mesoporous material mainly occurs between the Ce³⁺ and the central Eu³⁺ ion. They show the characteristic emission of Ce³⁺ 5d → 4f (200–320 nm) and Eu^{3+ 5}D₀ → ⁷F _J (J = 1–4, with ⁵D₀ → ⁷F₁ orange emission at 588 nm as the strongest one) transitions, respectively. In addition, for comparison, the mesoporous material CeF₃: Eu³⁺/SBA-15/SS exhibits the characteristic emission of Eu³⁺ ion under UV irradiation with higher luminescence intensity than the other materials.     

Mesoporous TiO<Subscript>2</Subscript> microspheres synthesized via a facile hydrothermal method for dye sensitized solar cell applications

Mesoporous TiO₂ microspheres were successfully synthesized by a facile hydrothermal process and the obtained product was sintered at 450 °C. The sintered TiO₂ powder was characterised by powder X-ray diffraction pattern and the result shows pure anatase phase with good crystalline nature. The morphological image of field emission scanning electron microscopy and high resolution transmission electron microscopy shows spherical shape and size of the particles is around 100 to 300 nm. The Brunauer–Emmett–Teller surface area of synthesized TiO₂ material was 56.32 m² g^?1 and average pore width of synthesized materials was 7.1 and 9.3 nm. Bimodal pore structure of TiO₂ microspheres has been very effective for electrolyte diffusion into photoanode in dye sensitized solar cells. The synthesized anatase TiO₂ microsphere based dye sensitized solar cells have high surface area with light scattering effect to enhance the photocurrent and conversion efficiency than the commercial P25 photoanode material. The power conversion efficiency of synthesized mesoporous TiO₂ microspheres and commercial P25 material is 4.2 and 2.7 % respectively. Therefore bimodal mesoporous anatase TiO₂ microsphere appears to be a promising and potential candidate for dye sensitized solar cells (DSSC) application.     

Removal of gaseous toluene by using TiO<Subscript>2</Subscript> film doped of Ru-dye/Pt in a pilot scale photoreactor

The photodegradation efficiency (PE) of gaseous toluene was investigated by using titanium dioxide (TiO₂) film doped of ruthenium (Ru)-dye/platinum (Pt) in a 3,600 L pilot reactor. Ru-dye was applied as a sensitizer to enhance PE of toluene in both UV and visible wavelength range since its major peaks are 225 nm, 325 nm, 375 nm, and 525 nm. PE by using Pt/TiO₂ was more enhanced since Pt plays a role as an electron trapper in UV light range. The 3.2 μm thickness of TiO₂ film was optimized for the highest PE. The highest PE was 75%, 85%, and 90% by TiO₂, Pt/TiO₂, and Ru-dye/Pt/TiO₂ film, respectively.     

Adsorption and photocatalytic properties of TiO<Subscript>2</Subscript>/mesoporous silica composites from two silica sources (acid-leached kaolinite and Si-alkoxide)

Two different mesoporous silicas (MPS) were synthesized by hydrothermal treatment in NaOH solution of two SiO₂ sources. These were microporous silica (MicroPS) derived from selectively acid leached metakaolinite and tetraethylorthosilicate (TEOS). The hydrothermal syntheses of the MPSs were performed at a ratio of SiO₂/cetyltrimethyl- ammonium bromide (CTABr)/NaOH/H₂O = 1/0.1/0.3/150. The specific surface areas (S _BET) of the MPSs from MicroPS (MPS(M)) and TEOS (MPS(T)) were 1070 and 1020 m²/g, respectively. Composites of MPS (75 mass%) with TiO₂ (25 mass%) were prepared using both SiO₂ and two commercial TiO₂ powders, P25 and ST-01. The adsorption–desorption behavior of methylene blue (MB) by the four resulting composites and the two MPSs alone was unique in showing partially reversible behavior. The maximum MB adsorption, observed in the composite of ST-01 with MPS(M), designated (S/M), was 0.034 mmol/g. The rates of MB adsorption in the dark and photodecomposition under UV illumination were considerably different for the four composites and two TiO₂ powers, and followed the order ST-01 < S/T < P25 < P/T ≈ P/M ≪ S/M. The removal rate of MB by the composite S/M by adsorption and photodecomposition was further enhanced by heating at 700 °C. Direct photodecomposition of MB without adsorption in the dark was greatly enhanced in the composites, especially in that composed of MPS(M) and ST-01.