Synthesis and study of photoacoustic properties of (Pd/TiO<Subscript>2</Subscript>)/polystyrene nanocomposites

In this work, nanocomposites (Ncs) from Pd nanoparticles and TiO₂ (Pd-Nps-TiO₂) were supported on a polystyrene matrix (PS). Chemical liquid deposition, solvated metal atom dispersion and in situ polymerization were used in order to synthesize these Ncs. Colloid and nanocomposite characterization were performed by TEM, SEM, EDX, SAED and TGA. TEM analysis revealed a particle size of 7 nm for Coll-Styrene and 11 nm for Pd-Nps supported on TiO₂ after radical polymerization. SAED showed phases corresponding to both metallic Pd and TiO₂ anatase in the polymeric matrix. Molecular weight (MW) was determined by viscosimetric method. MW varies according to the initiator concentration and nanoparticle amount used for polymerization. The amount of nanoparticles increased the decomposition temperature of the Ncs by 10 °C, improving the thermal stability of these hybrid materials. Photoacoustic properties were evaluated in order to determine the effect of nanoparticles on thermal diffusivity (α) inside the matrix. Significant values of (α) were found for Ncs with Pd-Nps in contrast to PS and Pd/TiO₂ Ncs. Structural aspects and colloidal aggregation of Ncs were also studied.     

Preparation and characterization of mesoporous TiO<Subscript>2</Subscript>-pillared titanate photocatalyst

Mesoporous anatase TiO₂-pillared titanate has been successfully prepared by the exfoliation-restacking route. The resulting nanocomposite was characterized by powder X-ray diffraction, scanning electron microscope, thermogravimetric analysis, IR and UV–Vis spectroscopy, specific surface area and porosity measurements. It was revealed that the present nanocomposite exhibits greatly expanded specific surface area (~200 m² g⁻¹) with 2.8- and 6.6-nm-in-diameter mesopore structure, and that there exists an electronic coupling between the host titanate sheets and the guest anatase TiO₂ nanoparticles in the pillared system. The results of degradation of methylene blue under ultraviolet and visible radiation show that the present nanocomposite exhibits much higher photocatalytic activities than that of TiO₂ nanoparticles or layered titanate alone, which are based on the bandgap excitation and the dye sensitization.     

Synthesis of TiO<Subscript>2</Subscript> Nanoparticles by Microemulsion/Heat Treated Method and Photodegradation of Methylene Blue

In this work, TiO₂ nanoparticles were prepared by microemulsion (ME)/heat treated method and its photodecomposition property of methylene blue. Microemulsion (ME) consisted of water, cyclohexane and an anionic surfactant such as bis (2-ethylhexyl) sodium sulfosuccinate (AOT). Titanium tetraisopropoxide (TTIP) was dropped into the ME solution and then then TiO₂ nanoparticles were formed by the hydrolysis reaction between TTIP in the organic solvent and the water in the core of ME. The smallest diameter of the particles was 20 nm in the system of cyclohexane with surfactant when the molar ratio of water to surfactant was 2. The effect of the process parameters (water/surfactant ratio, different temperatures) on the final characteristics has been investigated, in terms of structural phase and particle size. The TiO₂ nanoparticles were characterized by means of X-ray diffraction, Transmission and scanning electron microscopy, Fourier-Transformed infrared and differential thermal analysis. TiO₂ nanoparticles prepared in this condition were collected as amorphous powder, and converted to anatase phase at less than 350 °C, which is lower than the ordinal phase transition temperature. The crystallite size and crystallinity increase with an increase of heat treated s temperature. The particles are shown to have a spherical shape and have a uniform size distribution. The size of nanoparticles raises with an increase of water/surfactant ratio. In the photocatalytic decomposition of methylene blue, the photocatalytic activity is mainly determined by the crystallinity of TiO₂. In addition, the TiO₂ heat treated at 350 °C shows the highest activity on the photocatalytic decomposition of methylene blue (k = 1.7 × 10⁻² min⁻¹).     

The TiO2–Clay-LDPE Nanocomposite Packaging Films: Investigation on the Structure and Physicomechanical Properties

The role of nanoclays and TiO₂ nanoparticle loadings were investigated on low density polyethylene crystalline structure, in addition to studying packaging film properties such as barrier, thermal and mechanical properties. The polymer crystal study indicated for the orthorhombic crystal phase and about 20% lower degree of crystallinity for nanocomposites containing more than 2 wt.% TiO₂ nanoparticles. Based on the X-ray diffraction technique, the dispersion of nanoclays was improved to almost good degree of clay exfoliation with the company of 4 wt.% TiO₂ nanoparticles. In agreement with XRD results, the TEM morphological studies mainly suggest that TiO₂ has a helpful effect on nanoclay exfoliation. The increase in degradation temperature of nanocomposites may be attributed to the formation of inorganic char on polymer melt. The barrier properties of TiO₂/clay nanocomposite packaging films depend mainly on nanoclay loading with an unclear trend from TiO₂ nanoparticles. The increase in elastic modulus and the yield stress of nanocomposite films showed great effects on film mechanical properties by nanoclays.     

Synthesis and characterization of sol–gel derived PVA-titanium dioxide (TiO<Subscript>2</Subscript>) nanocomposite

Novel PVA/TiO₂ polymer nanocomposites have been prepared at low temperature via sol–gel route. XRD analysis showed the particles to be elongated along a- and b-direction but contracted along c-direction. PVA-assisted TiO₂ nanocomposite samples dried at a temperature of 35 °C were found to have ~12 nm particle size. It was found that the composite nanoparticles had an increased degree of crystallinity in comparison to pure TiO₂ dried at 80 °C. TEM analysis depicted the formation of highly dense nanorods (and prism)-like structure of increasing length and diameter depending on PVA concentration. Our studies revealed that by increasing the concentration of PVA in TiO₂ the band gap was lowered from 3.55 to 1.65 eV. The photoluminescence studies showed that emission shifts towards higher wavelength (417–457 nm) accompanied by a reduction in impurity centres with increasing concentration of PVA in TiO₂.     

Hydrophilicity and crystallization behavior of PVDF/PMMA/TiO<Subscript>2</Subscript>(SiO<Subscript>2</Subscript>) composites prepared by in situ polymerization

Composites with enhanced hydrophilicity were prepared by adding TiO₂ or SiO₂ nanoparticles during the in situ polymerization of methyl methacrylate (MMA) in poly(vinylidene fluoride) (PVDF). The hydrophilicities of the PVDF/PMMA/TiO₂(SiO₂) composites generated in this manner were characterized by contact angle measurements and atomic force microscopy (AFM). The hydrophilicity was dependent on nanoparticle content; it gradually increased with increasing TiO₂ (or SiO₂) content when the TiO₂ (or SiO₂) content was no more than 4 wt% of PVDF. A homogeneous dispersion of the TiO₂ (or SiO₂) nanoparticles in the composite matrix was observed in scanning electron microscope (SEM) images. Based on Fourier transform infrared (FTIR) spectra and wide angle X-ray diffraction (WAXD) analyses, the crystalline phase composition of PVDF was not influenced by the addition of TiO₂ (or SiO₂); PVDF crystallized predominantly in the α phase after in situ polymerization. Nevertheless, the nanoparticles can promote the formation of the β phase of PVDF in composites; the β-phase content increased with increasing TiO₂ content, while it was almost independent of SiO₂ content.     

Synthesis of well-dispersed polyimide/TiO2 nanohybrid films using a pyridine-containing aromatic diamine

The sol–gel fabrication of new well-dispersed polyimide (PI)/TiO₂ nanohybrid films is reported. The PI matrixes are synthesized via the polycondensation of pyromellitic dianhydride and a diamine monomer containing several constructive functional groups which introduced some interesting features to the final nanocomposite (NC) materials. The TiO₂–heteroatom interactions associated with the flexible characteristic of polymer backbone (which facilitates the stated interactions) have been led to the fabrication of well-dispersed nanoparticles with less than 100 nm in sizes, as confirmed by means of transmission electron microscopy. Thermal analysis techniques (TGA and DSC) have shown the superior thermal stability of fabricated NCs. The UV–Vis spectroscopy has illustrated a growing trend in the absorption efficiency along with the increase in TiO₂ contents. The created TiO₂ nanoparticles showed amorphous structures according to the X-ray diffraction patterns.     

Multifunctionality of poly(vinyl alcohol) nanofiber webs containing titanium dioxide

We prepared titanium dioxide/PVA nanocomposite fiber webs for application in multifunctional textiles by electrospinning. The morphological properties of the TiO₂/PVA nanocomposite fibers were characterized using scanning electron microscopy and transmission electron microscopy. Layered fabric systems with electrospun TiO₂ nanocomposite fiber webs were developed using various concentrations of TiO₂ and a range of web area densities, and then the UV‐protective properties, antibacterial functions, formaldehyde decomposition ability, and ammonia deodorization efficiency of the fabric systems were assessed. Layered fabric systems with TiO₂ nanocomposite fiber webs containing 2 wt% TiO₂ nanoparticles at 3.0 g m^?2 web area density exhibited an ultraviolet protection factor of greater than 50, indicating excellent UV protection. The same system showed a 99.3% reduction in Staphylococcus aureus. Layered fabric systems with TiO₂ nanocomposite fiber webs containing 3 wt % TiO₂ nanoparticles at 3.0 g m^?2 web area density exhibited a 85.3% reduction in Klebsiella pneumoniae. Titanium dioxide nanocomposite fiber webs containing 3 wt % TiO₂ nanoparticles at 3.0 g m^?2 web area density exhibited a formaldehyde decomposition efficiency of 40% after 2 h, 60% after 4 h, and 80% after 15 h under UV irradiation. The same system showed an ammonia deodorization efficiency of 32.2% under UV irradiation for 2 h. These results demonstrate that TiO₂ nanocomposite fibers can be used to produce advanced textile materials with multifunctional properties. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Electrochemical polymerization and characterization of a poly(azulene)-TiO<Subscript>2</Subscript> nanoparticle composite film

A poly(azulene)-TiO₂ composite film (PAz-TiO₂) was synthesized electrochemically by oxidation of azulene in an electrolyte medium containing TiO₂ nanoparticles. Polymerization was performed under magnetic stirring in an acetonitrile solution containing tetrabutylammonium hexafluorophosphate as the electrolyte salt. Influence of the concentration of TiO₂ in the reaction suspension on the electrochemical and optical properties and on the structure of the composite films was studied by cyclic voltammetry, ex situ Raman and FTIR reflection spectroscopy and in situ UV–vis and FTIR spectroelectrochemical techniques. Morphology of the composite films was studied by Scanning Electron Microscopy and the amount and distribution of the TiO₂ nanoparticles within the polymeric matrix by Inductively Coupled Plasma Mass Spectrometry with laser ablation. Addition of TiO₂ in the reaction suspension had a small catalytic activity for the polymerization of Az. Inclusion of TiO₂ nanoparticles in PAz did not affect the voltammetric behavior or the chemical structure of the formed polymer films. However, a different chain conformation and morphology of the film was formed when synthesized in presence of TiO₂ compared to the plain PAz film. It was also found that the film morphology was more homogeneous when the concentration of TiO₂ was ≥10 mM in the polymerization solution than films polymerized without any TiO₂.     

Transparent and flexible films of new segmented polyurethane nanocomposites incorporated by NH2-functionalized TiO2 nanoparticles

In this work, TiO₂ nanoparticles are surface modified by NH₂-terminated organic moieties arised from 4,4′-methylene diphenyl diisocyanate (MDI). These nanoparticles are incorporated into ether-based segmented polyurethane (SPU) matrix. MDI is utilized as monomer together with poly(tetramethylene oxide) (PTMO) comonomer for preparing the final polymer as well. The NH₂-functionalized TiO₂ nanoparticles are covalently linked to the NCO terminals of the resulting SPU macromolecules during film preparation stage. Therefore, in addition to butylene glycol, these surface modified nanoparticles with enhanced organophilicity could play the role of the second chain extender of NCO-capped SPU macromolecules through formation of urea linkages. Optical and thermal behaviors of the transparent and flexible film (SPU/TiO₂–MDI) is compared with those of unmodified TiO₂ (SPU/TiO₂) and TiO₂-unloaded SPU films. Though the particle loading is only 5 wt.%, incorporation of TiO₂ and TiO₂–MDI nanoparticles into the SPU polymer enhances significantly the light absorption in UV region at 300–400 nm. SEM images of the prepared films clearly show a considerable decrease in particle aggregation for TiO₂–MDI into SPU matrix compared to that of unmodified TiO₂. TG analyses indicate a one-step decomposition pattern with onset temperatures of about 360 and 380 °C for neat SPU and SPU/TiO₂–MDI, respectively. Moreover, DTA thermograms of both nanocomposites show obviously two exothermic phase transitions in the thermal range of 330–440 °C.     

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.     

Structural and ultraviolet‐protective properties of nano‐TiO2‐doped polypropylene filaments

Textiles, with appropriate light absorbers and suitable finishing methods, can be used as ultraviolet (UV) protection materials. In this study, we investigated the effects of nano‐TiO₂ particles on the UV‐protective and structural properties of polypropylene (PP) textile filaments. Master batches of PP/TiO₂ nanoparticles were prepared by melt compounding before spinning, and filaments incorporating 0.3, 1, and 3% TiO₂ nanoparticles were spun in a pilot melt‐spinning machine. The structural properties of the nanocomposite fibers were analyzed with scanning electron microscopy, X‐ray diffractometry, differential scanning calorimetry, and tensile tests. The UV‐protection factor was determined to evaluate the UV‐protective properties of the filaments. In conclusion, although the structure and mechanical properties of the nanocomposite filaments were slightly affected by the addition of nano‐TiO₂, the UV‐protective properties of the PP filaments improved after treatment with nano‐TiO₂, and the nanocomposite filaments exhibited excellent UV protection. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Effect of Nickel as Dopant in Mn/TiO<Subscript>2</Subscript> Catalysts for the Low-Temperature Selective Reduction of NO with NH<Subscript>3</Subscript>

Nickel doped manganese oxide supported on titania materials were investigated for the low-temperature NH₃-SCR. For this purpose, a series of Ni modified Mn/TiO₂ catalysts were prepared and evaluated for the low-temperature SCR of NO with ammonia in the presence of excess oxygen. The catalytic performance of these materials was compared with respect to the nickel weight percentage in order to examine the correlation between physicochemical characteristics and reactivity of optimized materials. It was found that the 5% Mn–2% Ni/TiO₂ catalyst showed the highest activity and yielded 100% NO conversion at 200 °C. XRD results reveal highly dispersed manganese–nickel species on TiO₂ support for the Mn–Ni/TiO₂ catalysts. Our TPR data results suggested an increase in reducibility of manganese species in Mn–Ni/TiO₂ catalysts. The absence of the high-temperature (736 K) peak indicates that the dominant phase is MnO₂. This increase of reducibility and dominant MnO₂ phase seems to be the reason for the enhanced activity and time on stream patterns of nickel-promoted titania-supported manganese catalysts. BET results illustrate that the high NO conversion is strongly dependant on the specific surface area and pore volume of this catalyst. All the physicochemical techniques we used suggested that the composition of manganese and nickel oxides on the support surface is playing an important role for the enhancement of NO conversion and the prominent time on stream stability.     

Mechanism of formation of the complex oxide Na<Subscript>2</Subscript>Nd<Subscript>2</Subscript>Ti<Subscript>3</Subscript>O<Subscript>10</Subscript>

The processes of phase formation in the Nd₂O₃-TiO₂-Na₂CO₃ system have been investigated in the temperature range 500–1100°C. The mechanism of the high-temperature solid-phase reaction of formation of the complex oxide Na₂Nd₂Ti₃O₁₀ has been studied. It has been established that the Na₂Nd₂Ti₃O₁₀ compound is formed from the intermediate product Na_0.5Nd_0.5TiO₃ with a perovskite structure in the temperature range 830–890°C and from the NaNdTiO₄ oxide with a perovskite-like layered structure in the temperature range 960–1100°C.     

Manganese oxide nanocomposites with improved surface area prepared by one-pot surfactant route for electro catalytic and biosensor applications

Braunite phase manganese oxide is naturally available in manganese–silicate rocks with minor amount of silicate content. New synthetic route is attempted to prepare the manganese oxide nanoparticle and silica incorporated manganese oxide nanocomposite in the present study. XRD patterns reveal the braunite phase formation for as synthesized manganese oxide nanocomposite and silica incorporated MnO₂ nanocomposite materials. Improved BET surface area values are achieved by one step surfactant assisted method (i.e., 82 and 151 m²/g) compared to conventional route prepared manganese oxide nanomaterial. Flaky pastry type morphology was observed for as synthesized Si–MnO₂ nanocomposites. Cyclic voltammetry studies predict the electrocatalytic activity of manganese oxide nanoparticle and Si–MnO₂ nanocomposite in presence of electroactive redox couple. Si–MnO₂ nanocomposite modified glassy carbon (GC) electrode shows the effective electroactive response in presence of Fe²⁺/Fe³⁺ redox couple at 0.69 V with current density of 0.343 × 10⁻⁵ A/cm² compared to manganese oxide nanoparticle modified GC electrode. The biosensor responses for ascorbic acid have been tested in the present study and manganese oxide nanoparticle modified GC electrode shows effective response at low concentration of (1 × 10⁻⁵ M) ascorbic acid in phosphate buffer solution. Manganese oxide nanoparticle modified electrode shows the better response with current density value of 0.115 × 10⁻⁵ A/cm² compared to Si–MnO₂ nanocomposite.     

Single-step polyol synthesis of alloy Pt<Subscript>7</Subscript>Sn<Subscript>3</Subscript> versus bi-phase Pt/SnO<Subscript>x</Subscript> nano-catalysts of controlled size for ethanol electro-oxidation

Disordered alloy and bi-phase PtSn nanoparticles of nominal Pt:Sn ratio of 70:30 atomic % with controlled size and narrow size distribution were synthesized using a single-step polyol method. By adjusting the solution pH it was possible to obtain Pt₇Sn₃ nanoparticles of various sizes from 2.8 to 6.5 nm. We found that the presence of NaOH in the synthesis solution not only influenced the nanoparticle size, but as it was revealed by XRD, it apparently also dictated the degree of Pt and Sn alloying. Three catalysts prepared at lower NaOH concentrations (C_NaOH < 0.15 M) showed disordered alloy structure of the nominal composition, while the other three catalysts synthesized at higher NaOH concentrations (C_NaOH > 0.15 M) consisted of bi-phase nanoparticles comprising a crystalline phase close to that of pure Pt together with an amorphous Sn phase. These observations are plausibly due to the phase separation and formation of monometallic Pt and amorphous SnO_x phases. A proposed reaction mechanism of Pt₇Sn₃ nanoparticle formation is presented to explain these observations along with the catalytic activities measured for the six synthesized carbon-supported Pt₇Sn₃ catalysts. The highest catalytic activity towards ethanol electro-oxidation was found for the carbon-supported bi-phase catalyst that formed the largest Pt (6.5 nm) nanoparticles and SnO_x phase. The second best catalyst was a disordered alloy Pt₇Sn₃ catalyst with the second largest nanoparticle size (5 nm), while catalysts of smaller size (4.5–4.6 nm) but different structure (disordered alloy vs. bi-phase) showed similar catalytic performance inferior to that of the 5 nm disordered alloy Pt₇Sn₃ catalyst. This work demonstrated the importance of producing bi-metallic PtSn catalysts with large Pt surfaces in order to efficiently electro-oxidize ethanol.     

Synthesis, characterization, and antibacterial activity of metal nanoparticles embedded into amphiphilic comb-type graft copolymers

The synthesis, spectroscopic characterization, and antimicrobial efficiency of gold and silver nanoparticles embedded in novel amphiphilic comb-type graft copolymers having good film-forming properties have been described. Amphiphilic comb-type graft copolymers were synthesized by the reaction of chlorinated polypropylene (PP) (M _w = 140,000 Da) with polyethylene glycol (PEG) (M _n  = 2,000 Da) at different molar ratios. Metal nanoparticles embedded graft copolymers were prepared by reducing solutions of the salts of silver or gold and the copolymer in tetrahydrofuran. The optical properties of the metal nanoparticle embedded copolymers were determined by using UV–visible spectroscopy. Surface plasmon resonance (SPR) of the gold and silver nanoparticle embedded copolymers in toluene was observed at a maximum wavelength (λ_max) of 428 and 551 nm in the UV–VIS absorption spectra, respectively. The average particle diameters of the gold and silver nanoparticles were found to be 50 nm from the high resolution scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). Amphiphilic polymer films containing silver and gold nanoparticles were found to be highly antimicrobial by virtue of their antiseptic properties to Escherichia coli and Staphylococcus aureus.     

Magnetic electrospun fluorescent polyvinylpyrrolidone nanocomposite fibers

Magnetic nanoparticles (MNPs) were synthesized from facile thermodecomposition of iron pentacarbonyl and the subsequent silica coating on the MNP surface was achieved via a modified Stöber process to obtain the core–shell composite structured particles (MNPs-SiO₂). MNPs-SiO₂ were then incorporated into polyvinylpyrrolidone (PVP) to form nanocomposite fibers via an electrospinning process with optimized operational parameters such as polymer concentration, applied electrical voltage, feed rate and tip-to-collector distance. All these parameters show an unusual effect on the produced fiber diameter. Contrary to the conventional observation, i.e., increasing the applied voltage and feed rate or decreasing the distance could increase the fiber diameter; a reduced average fiber diameter was observed in this study and could be explained from the stretching and contraction force balance within the fiber during electrospinning. The size of the resulting PVP fibers is correlated to the corresponding rheological behaviors of the PVP solutions with different concentrations. The MNPs-SiO₂/PVP nanocomposite fibers exhibit a similar thermal decomposition temperature (386.3 °C) as that (387.8 °C) of pure PVP. Meanwhile, unique fluorescent and magnetic properties have been incorporated simultaneously in the nanocomposite fibers with the addition of small amount of MNPs-SiO₂ nanoparticles.     

Water vapor adsorption and photocatalytic pollutant degradation with TiO2–sepiolite nanocomposites

A new nanocomposite containing a titanium dioxide photocatalyst and low-cost sepiolite was prepared and tested for its potential multifunctional application in water vapor adsorption and pollutant photodegradation. The nanocomposite was characterized by X-ray diffraction (XRD), X-ray fluorescence (XRF), thermogravimetric and differential thermogravimetric analyses (TGA/DTG), scanning electron microscopy (SEM) with energy dispersive X-ray analysis (EDX) and surface area (BET) measurements. The XRD patterns of the nanocomposites exhibited the characteristic sepiolite and anatase reflections, while the SEM images revealed the surface morphology of the raw sepiolite after the modification with the sol gel prepared with TiO₂. In the TGA/DTG, up to 100 °C, three stages of water removal were analyzed and attributed to surface and zeolitic water loss. Upon TiO₂ loading, the overall mass loss of sepiolite was reduced to half, but the three stages of water loss were rearranged with low loading (10 wt.%) or were reduced to two stages with higher loading (20 wt.%). The hydrophilic nature of the raw sepiolite was retained after the TiO₂ loading, while the water vapor uptake was reduced to 20–30% with relative humidities from 30 to 80% and loadings up to 20 wt.%. In addition, the efficiencies of the supported photocatalysts were investigated using β-naphthol as a model pollutant compound. All prepared catalysts exhibited higher activities than when using the bare TiO₂ sample. Therefore, the TiO₂–sepiolite nanocomposite can be potentially applied for combined photocatalytic degradation processes and water vapor adsorption to allow for evaporative cooling.     

Photoelectrochemical reaction of biomass-related compounds in a biophotochemical cell comprising a nanoporous TiO<Subscript>2</Subscript> film photoanode and an O<Subscript>2</Subscript>-reducing cathode

Photoelectrochemical decomposition of bio-related compounds such as ammonia, formic acid, urea, alcohol, and glycine by a biophotochemical cell (BPCC) comprising a nanoporous TiO₂ film photoanode and an O₂-reducing cathode generating simultaneously electrical power was investigated. The bio-related compounds studied were all photodecomposed by the present BPCC when they were either liquid or soluble in water. It was shown that ethanol exhibits similar characteristics both under 1 atm O₂ and air as studied by cyclic voltammograms. Although the present BPCC utilizes only UV light, a solar simulator at AM 1.5G and 100 mW cm⁻² light intensity gave also moderate photocurrent–photovoltage (J–V) characteristics with about 2/5 of the short circuit photocurrent (J _sc) values (J _sc) of that under a Xe lamp irradiation at the intensity of 503 mW cm⁻². It was demonstrated that varieties of bio-related compounds can be used as a direct fuel simultaneously for photodecomposition and electrical power generation. The charge transport processes in the BPCC operation were analyzed using glycine by an alternating current impedance spectroscopy, showing that the charge transfer reactions on the photoanode and the cathode surfaces compose the major resistance for the cell performance.