Surface Area Of TiO2 Nanoparticles Research Articles

Ultrasensitive detection of xylene gas by cauliflower-like Au-TiO2 core-shell nanoparticles

TiO2 nanoparticles (NPs) and Au-TiO2 core-shell NPs (C-S NPs) were synthesized for xylene gas detection. Morphological, phase, and chemical studies demonstrated the successful generation of Au-TiO2 C-S NPs with a cauliflower-like morphology and desired composition. Also, the surface area of TiO2 NPs was 8.46, which increased to 23.88 m2/g for Au-TiO2 C-S NPs, due to the creation of a porous TiO2 shell around the Au core. The response of the TiO2 NPs to 50 ppm xylene was 14.19 at 500°C, while it increased to 165.77 at a lower temperature (450°C). Furthermore, while the TiO2 NPs gas sensor has no selectivity to xylene gas, the TiO2 C-S NP gas sensor exhibited excellent selectivity. Overall, incorporation of Au in TiO2 in the form of a C-S structure improved the performance of the sensor to sense xylene. Improved xylene sensing for the TiO2 C-S NPs stemmed from the high surface area and porous nature, oxygen defects, and formation of Au-TiO2 Schottky barriers. This research demonstrates the development of high-output xylene sensors by means of Au-TiO2 with a C-S structure.

Visible light-induced photocatalytic and antibacterial adhesion properties of superhydrophilic TiO2 nanoparticles

Bacterial infections triggered by patient or healthcare worker contact with surfaces are a major cause of medically acquired infections. By controlling the kinetics of tetrabutyl titanate hydrolysis and condensation during the sol–gel process, it is possible to regulate the content of Ti3+ and oxygen vacancies (OVs) in TiO2, and adjust the associated visible light-induced photocatalytic performance and anti-bacterial adhesion properties. The results have shown that the Ti3+ content in TiO2 was 9.87% at the calcination temperature of the reaction system was 300 °C and pH was 1.0, corresponding to optimal photocatalytic and hydrophilic properties. The formation of a hydrated layer on the superhydrophilic surface provided resistance to bacterial adhesion, preventing cross-contamination on high-touch surfaces. The excellent photocatalytic self-cleaning performance and anti-bacterial adhesion properties can be attributed to synergistic effects associated with the high specific surface area of TiO2 nanoparticles, the mesoporous structure, and the presence of Ti3+ and OVs. The formation of superhydrophilic self-cleaning surfaces under visible light can serve as the basis for the development of a new class of anti-bacterial adhesion materials.

Investigation on optical properties and photovoltaic performance of solid-state dye-sensitized solar cells comprised of photoanodes of titanium dioxide nanoparticles calcinated at different temperatures

Dye-sensitized solar cells (DSSCs) were constructed using photoanodes of TiO2 nanoparticles (Degussa P25) calcinated at diverse temperatures. The calcinated TiO2 nanoparticles were characterized by X-ray diffraction (XRD) technique and N719 dye anchored TiO2 thin films were subjected to diffuse reflectance spectral and dye desorption studies. The band gaps of TiO2 nanoparticles calcinated at higher temperatures (700 and 900 °C) were shifted to lower energy levels by predominant anatase phase transformation into rutile and increase in the particles size. The performance of DSSCs with TiO2 (Degussa P25) nanofiller incorporated solid-state PEO electrolyte was examined at light intensity of 60 mW cm−2. The DSSC with TiO2 (Degussa P25) nanoparticles photoanode was exhibited overall efficiency of 1.86%, which was ∼4.9 and 9.8-folds greater over the DSSCs having photoanodes of TiO2 nanoparticles calcinated at 700 and 900 °C, respectively. This can be attributed to higher surface area of TiO2 nanoparticles that facilitates higher dye adsorption and predominant anatase phase for favorable electron transfer. The DSSCs stability was confirmed through chronoamperometry experiments.

Decoration of TiO2 nanoparticles on TiO2 microcone array with holes as photoanodes of fiber-shaped dye-sensitized solar cells

Fiber-shaped dye-sensitized solar cell (FDSC) is one of efficient energy generation devices for soft electronics, owing to low-cost and dim-light operable features. The key component of FDSC is photoanode, which is responsible for absorbing incident light and generating charges. Designing TiO2 structure is significant for fabricating efficient photoanode of FDSC. In this study, it is the first time to fabricate TiO2 nanoparticle-decorated TiO2 microcone array (TMC) with holes using simple two-step anodization and dip-coating processes as semiconductor on photoanode of FDSC. Different H2SO4 concentrations is used to creating holes on TMC. Holes are generated on TMC in anodization process, but TMC are detached from Ti wire more seriously when higher H2SO4 concentration is used. The optimized photoanode of FDSC is prepared using 30 mM H2SO4. The optimized FDSC shows solar-to-electricity conversion efficiency (η) of 2.52%, while the FDSC with the pure TMC photoanode only shows η of 1.68%. The better photovoltaic performance of FDSC comprising TiO2 nanoparticle-decorated TMC with holes photoanode is owing to abundant contacts between TMC and TiO2 nanoparticles and high surface area of TiO2 nanoparticles for dye adsorption. The highest collection efficiency of 92.21% is also achieved for the FDSC with the optimized photoanode, analyzed using intensity modulated photocurrent/voltage spectroscopy spectra.

Phosphorus-doped TiO2 for visible light-driven oxidative coupling of benzyl amines and photodegradation of phenol

A kind of phosphorus-doped TiO2 (P-TiO2) is fabricated by boric acid-induced hydrolysis of tetrabutyl titanate in ethanol solution of triphenylphosphine, then calcination and removal of boron oxide resulted from boric acid. Under the irradiation of blue light-emitting diode (LED), P-TiO2 can successfully realize the oxidative coupling of benzylamine (conversion >95%, selectivity >99%) with air as an oxidant. The photocatalyst exhibits excellent recycling stability and broad applicability for various benzylamine derivatives. Besides, the photodegradation of phenol can also be conducted smoothly with the photocatalyst under the irradiation of Xenon lamp. Control experiments demonstrate that boric acid-induced hydrolysis and calcination temperature determine the size-distribution and surface area of TiO2 nanoparticles, which further impact the photocatalytic performance. Density Functional Theory (DFT) calculations demonstrate that the orthophosphate species covalently bonding to the titania surface facilitates the adsorption of oxygen molecule on the surface of P-TiO2 by forming P–O bond.

Influence of nickel and lanthanum ions co-doping on photocatalytic properties of TiO2 for effective degradation of reactive yellow 145 in the visible region

Nickel and lanthanum co-doped TiO2 nanoparticles with different metal loading, narrow particle size distribution, and high surface area are synthesized using the sol–gel method. The nanoparticles are further characterized using different techniques like flame atomic absorption spectroscopy (FAAS), specific surface area and porosity measurements, X-ray diffraction (XRD) analysis, fourier transform infrared spectroscopy (FT-IR), UV–vis diffused reflectance spectroscopy (DRS), raman analysis, scanning electron microscopic studies (SEM), photoluminescence (PL) studies, X-ray photoelectron spectroscopy (XPS) and electrochemical impedance spectroscopic measurements (EIS). The experimental results of XRD analysis indicated that the co-doping of TiO2 with lanthanum (La) and nickel (Ni) results in an increased in the surface area of TiO2 nanoparticles accomplished by a decrease in the crystallite size from 18.00 to 10.42 nm. The appearance of a new absorption band in DRS spectra at 721 nm caused by the Ni+2 and La+3 doping is responsible for the enhancement of the photocatalytic degradation under visible light. The increased oxygen vacancies, surface defects as well as reduced recombination of charge carriers are confirmed by the PL studies. The photocatalytic experiment for Reactive Yellow-145 (RY-145) is carried out using 1.00 g/L of modified TiO2 suspension at different values of pH and temperature. The experimental results revealed that 96.5% of RY-145 is degraded after a short time of irradiation. The maximum degradation is achieved in case of nanoparticles co-doped with 5% Ni and 3% La ion. Furthermore, the adsorption experiment is also carried out to explore the adsorption of dye by photocatalytic support. The photocatalytic degradation of dye is further confirmed by measuring chemical oxygen demand (COD) values before and after degradation.

Poly 3-Thenoic acid sensitized, Copper doped anatase/brookite TiO2 nanohybrids for enhanced photocatalytic degradation of an organophosphorus pesticide

A series of heterogeneous poly 3-Thenoic acid (P3TA) sensitized, Copper (Cu) doped anatase/brookite TiO2 (Cu-TiO2) nanohybrid photocatalysts (P3TA/Cu-TiO2) were facilely synthesized using modified sol-gel method by taking different weight percentages (wt%) of P3TA to TiO2 at 20 °C temperature. X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, Thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), Ultraviolet-Visible diffuse reflectance spectroscopy (UV–vis DRS), Field emission scanning electron microscopy (FESEM) with energy dispersive X-ray spectroscopy (EDX), High resolution transmission electron microscopy (HRTEM) and Brunauer-Emmet-Teller (BET) surface area analyses were performed to characterize the as prepared nanohybrids and their photocatalytic performances were then investigated by degrading an organophosphorous pesticide (malathion) under visible light irradiation. The characterization results revealed that P3TA surface sensitization and Copper doping in TiO2 lead to formation of agglomerated multi-particle nanohybrids with good thermal stability compared to pure TiO2. The nanohybrids exhibited a strong and broad absorption in visible range, good adsorption capacity and enhanced photocatalytic activity indicated the narrowed bang gap, decreased particle size and increased surface area of TiO2 nanoparticles. Surface chemical composition analysis showed the presence of the constituent elements of both the P3TA and Cu-TiO2 nanoparticles confirmed the strong interfacial interaction between the P3TA and Cu-TiO2,which further supported by FT-IR results. Photoluminescence and radical scavenger experiments confirmed that hydroxyl radicals (OH) are the main reactive species responsible for the oxidative degradation of malathion. Effects of different nanohybrid/malathion operating conditions on the photocatalytic activity were investigated and a simple plausible mechanism was proposed accordingly.

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.

Dielectric and thermal properties of epoxy resins with TiO2 nanowires

Epoxy based composites with reinforced dielectric properties were successfully synthesized by using TiO2 nanowires as inorganic filler. TiO2 nanoparticle/epoxy composites were also prepared as a contrast. TiO2 nanowires were synthesized by a hydrothermal method, with an average diameter of 50 nm and a length of 5 µm. TiO2 nanoparticles were purchased with average diameter of ~60 nm. Scanning electron microscopy images show that two types of fillers are both homogeneously dispersed in the matrix. Although the specific surface area of TiO2 nanoparticles is about twice of that of TiO2 nanowires, remarkable improved dielectric constant, enhanced electrical and thermal conductivity, higher space charge accumulation and stronger charge carrier mobility were observed in nanowire filled epoxy resin at the same filler content. Meanwhile, nanowires composites exhibit excellent glass transition temperature and thermal stability. These results indicated that the geometry of filler had a profound impact on the performance of epoxy composites, and nanowire filling is more effective than nanoparticle filling to enhance the properties of epoxy resin.

Synthesis of graphene quantum dots from corn powder and their application in reduce charge recombination and increase free charge carriers

GQDs have been synthesized by using a novel and green precursor (corn powder). Furthermore, GQDs/TiO2 composite has been prepared by using graphene quantum dots as capping agent. Incorporation of graphene quantum dots in TiO2 nanoparticles reduce charge recombination, extend the absorption spectrum of TiO2 to the visible region, and increase the accessible surface area of TiO2 nanoparticles. Therefore, the significant enhancement of photocatalytic activity for degrading the Rhodamin B has been achieved. Characterization of the samples was carried out by Fourier transformed infrared (FT-IR) spectroscopy, UV–Vis spectroscopy, Field-emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM), and photoluminescence (PL).

Modification of TiO2 nanoparticles by HZSM-5 for the enhancement in photodegradation of Acid Green 25

A great approach for the preparation of TiO2 supported on HZSM-5 photocatalyst was employed by an energy efficient microwave assisted technique. Titanium tetraisopropoxide (TTIP) was used as a titanium precursor and medium pore size HZSM-5 with high thermal and chemical resistance used as a support. The amount of TTIP was varied in order to obtain different TiO2 loading of 20, 30 and 40 wt% on HZSM-5. The obtained nanomaterials were studied by a set of complementary characterization techniques including X-ray diffraction, transmission electron microscopy, scanning electron microscopy, energy dispersive spectroscopy, Fourier transform-infrared spectroscopy, surface area measurement (BET) and diffuse reflectance spectroscopy. The present research is mainly focused on the enhancement of surface area of TiO2 nanoparticles by using HZSM-5 as a support. The obtained nanomaterials were tested for the degradation of Acid Green 25 under UV light (365 nm). A maximum 96 % photodegradation of dye was achieved by utilizing most efficient TiO2(30 %)/HZSM-5 at 0.1 g/dm3 catalyst within 60 min under UV light.

Preparation of TiO2-based nanotubes/nanoparticles composite thin film electrodes for their electron transport properties

The composite thin film electrodes were prepared with one-dimensional (1D) TiO2-B nanotubes (NTs) and zero-dimensional TiO2 nanoparticles (NPs) based on different weight ratios. The electron transport properties of the NTs/NPs composite thin film electrodes applied for dye-sensitized solar cells had been investigated systematically. The results indicated that although the amount of dye adsorption decreased slightly, the devices with the NTs/NPs composite thin film electrodes could obtain higher open-circuit voltage and overall conversion efficiency compared to devices with pure TiO2 NPs electrodes by rational tuning the weight ratio of TiO2-B NTs and TiO2 NPs. When the weight ratio of TiO2-B NTs in the NTs/NPs composite thin film electrodes increased, the density of states and recombination rate decreased. The 1D structure of TiO2-B NTs can provide direct paths for electron transport, resulting in higher electron lifetime, electron diffusion coefficient and electron diffusion length. The composite thin film electrodes possess the merits of the rapid electron transport of TiO2-B NTs and the high surface area of TiO2 NPs, which has great applied potential in the field of photovoltaic devices.

Carbon nanotubes-dispersed TiO2 nanoparticles with their enhanced photocatalytic activity

A novel carbon nanotubes (CNTs)-dispersed route is used to prepare high-activity titanium dioxide nanoparticles (TiO2). Field-emission scanning electron microscopy and transmission electron microscopy reveals that the irregular TiO2 nanoparticles with diameters of 10–20nm are highly dispersed. X-ray diffraction and specific surface area measurement show that high-activity anatase crystal is formed and the specific surface area of TiO2 nanoparticles is 147.36m2/g. The photoactivity of TiO2 was tested by photodegradation of Rhodamine B. The result shows that the photocatalytic activity of TiO2 nanoparticles prepared by the CNTs-dispersed route is three times higher than that by conventional hydrothermal treatment.

Hybrid Ag@TiO2 core–shell nanostructures with highly enhanced photocatalytic performance

A new synthetic approach has been developed to prepare silver@titanium dioxide (Ag@TiO2) core–shell nanostructures with controllable size, shape, crystal phase and function 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 ∼100 ° C in our case), tunable TiO2 shell thickness, high yield and good reproducibility. The experimental results show that the Ag@TiO2 core–shell nanostructures exhibit excellent photocatalytic activity compared to the commercial TiO2 (P25) and Ag-doped TiO2 nanocomposite in the degradation of organic dye molecules (e.g. methyl orange) with ultraviolet (UV) irradiation. This could be attributed to the large surface area of TiO2 nanoparticles for maximum harvesting of UV light, mixed anatase and rutile crystalline phases in the TiO2 shell and the effective charge separation between Ag and TiO2 that can reduce the possible recombination of electron–hole (e−–h+) pairs within TiO2 generated under UV radiation. To further understand the charge separation situation within Ag–TiO2 composites, theoretical simulation (e.g. density functional theory, DFT) was employed in this study. The DFT simulation results indicate that for the Ag@TiO2 core–shell nanostructures, photo-generated electrons transfer readily from the external TiO2 layer to the internal Ag layer with heavy accumulation compared to those doping Ag on TiO2 surfaces, which may reduce the recombination of e−–h+ pairs and thus enhance the photocatalytic efficiency. The findings may open a new strategy to synthesize TiO2-based photocatalysts with highly enhanced efficiency for environmental remediation applications.

Oriented ZnO nanotubes arrays decorated with TiO2 nanoparticles for dye-sensitized solar cell applications

Dye-sensitized solar cells (DSSCs) based on a novel composite photoanode of TiO2 nanoparticles coating on electrodeposited ZnO nanotube arrays are fabricated and characterized. An efficiency of 3.94 % is achieved for the composite cell, increasing 86.7 % than 2.11 % of the ZnO nanotubes cell. The short-circuit current (Jsc) and open-circuit voltage (Voc) are also enhancing 52.9 % and 25.3 %, respectively. The improvements are because of the high surface area of TiO2 nanoparticles, as well as fast electron transport and light scattering effect of ZnO nanotubes.

H2 production by γ and He ions water radiolysis, effect of presence TiO2 nanoparticles

The effect of TiO2 particles on the yield of H2 formation under water radiolysis is measured. Irradiations were performed using a 60Co γ−ray source as well as with He ions particles (4He2+) generated by a cyclotron with an external beam energy of 6 MeV. The resulting hydrogen as a stable product of radiolysis was measured by mass spectrometry. G(H2) obtained for water radiolysis by He ions−irradiation in aerated and argon water are found to be 1.91 × 10−7 and 1.35 × 10−7 mol J−1, respectively. In the presence of titanium oxide anatase−type dispersed in water, under He ions−irradiation, G(H2) is found to increase slightly from 1.04 × 10−7 to 1.35 × 10−7 mol J−1 by increasing the specific surface from 8 to 253 m2/g, respectively. Under γ-irradiation, G(H2) is found to be 0.41 × 10−7 mol J−1 close to primary yield of hydrogen in presence of OH. Radical scavenger. In addition, radiolysis of water adsorbed in the titanium oxide with low water content, which corresponds to a few layers of water sorbed onto the solid surface gives a huge values of the G(H2). For the same amount of water, with using the dose absorbed by TiO2 particles, for He ions-irradiation, G(H2) increases from 14.5 × 10−7 to 35 × 10−7 mol J-1 by increasing the surface area of TiO2 nanoparticles from 4 to 52 m2/g, respectively. For γ−irradiation G(H2) is found to be 5.25 × 10−7 mol J-1 for the sample with 8 m2/g specific surface area.

Superhydrophilic surface modification of copper surfaces by Layer-by-Layer self-assembly and Liquid Phase Deposition of TiO2 thin film

A new method has been developed for the superhydrophilic surface modification of copper using versatile solution-based fabrication techniques. The high surface area of TiO(2) nanoparticles was exploited to create a thin film with increased surface energy that transformed copper materials from relatively hydrophobic to superhydrophilic. Copper exposed to ambient conditions resulting in a thin layer of copper oxide has a water contact angle near 90°, but following TiO(2) modification, the contact angle dropped to 0°. The thin film responsible for this drastic improvement in wettability proved durable by retaining its excellent properties throughout an extended application of thermal stress. SEM and Raman Spectroscopic analysis confirmed the structural integrity of the film before and after a durability test.

Electrochromic Properties of Asymmetric 4,4′-Bipyridinium Nanocomposites with Inorganic Nanoparticles

Asymmetric mono cationic 4,4'-bipyridiniums, 1-butyl-4,4'-bipyridinium bromide (BUBP) and 1-methyl-4,4'-bipyridinium iodide (MEBP) showed electrochromic properties from blue to transparent yellow. The electrochromic bipyridiniums, BUBP and MEBP, were introduced to solid state electrochromic cells by using a solution of the bipyridinium, TiO2, and polymer electrolyte composite. The 4,4'-bipyridinium derivatives was attached to TiO2 nanoparticles and decreased aggregation of TiO2 to afford EC dye-TiO2 nanoparticles with average diameter smaller than 20 nm, as determined by FE-SEM. An all solid state electrochromic cells prepared from the dye-TiO2 nanoparticles showed improved electrochromic response compared to that without TiO2. Thus the cell from the BUBP- TiO2 nanoparticles responded to a step potential of +/-2 V within 7 sec with coloration efficiency of 117. The redox cyclability of the bipyridinium-TiO2 nanoparticles cell was longer than that of the TiO2 free cells. The enhanced properties were attributed to the conductivity and the large surface area of TiO2 nanoparticles.