TiO2 NS Research Articles

Facile synthesis of reduced graphene oxide and graphitic carbon nitride modified titanium dioxide nanospheres for photoanode of dye-sensitized solar cell

Titanium dioxide/reduced graphene oxide nanocomposites (TiO2/rGO NCs) have been broadly utilized as photoanode materials for dye-sensitized solar cell (DSSC). Nevertheless, photoelectric conversion efficiency (PCE) of DSSC is diminished due to recombination of charges takes place between photoanode and electrolyte interface. Herein, we have prepared a triplet structure nanocomposite composed of TiO2 nanospheres, rGO and graphitic carbon nitride (TiO2 NS/rGO/g-C3N4 NC) for photoanode of DSSC. The ternary TiO2 NS/rGO/g-C3N4 NC photoanode has enhanced dye absorption considerably and as a consequence, improved light harvesting efficiency. Besides, the introduction of rGO and g-C3N4 on the TiO2 NS has effectually speeded up the transport of electrons and minimized the recombination of photogenerated charges. Consequently, the DSSC integrated with ternary TiO2 NS/rGO/g-C3N4 NC photoanode has exhibited ∼41 % increment in the PCE of 5.77 % when compared to PCE of the pristine TiO2 NS photoanode (4.10 %). This finding has proposed a simplistic approach to advance photovoltaic performance of the DSSC.

TiO2‐Based Hybrid Nanoscale Light Source

AbstractThe titanium dioxide nanosphere (TiO2 NS) is a moderate refractive index (MRI) nanostructure which can support Mie resonances such as magnetic dipole resonance (MDR), electric dipole resonance (EDR), etc. However, TiO2 is a wide indirect band gap (3.2 eV) semiconductor, and TiO2 NSs cannot be excited to emit luminescence by near‐infrared (NIR, 770 nm–800 nm) femtosecond (fs) lasers. In this paper, a MDR‐induced nanoscale plasmon source is conceived to provide a large number of hot electrons, which can be used to light up TiO2 NSs. The effect of different metals (Titanium‐Ti, Palladium‐Pd, Gold‐Au) as the MDR‐induced nanoscale plasmon sources on the optical response of TiO2‐based hybrid NSs is studied. This work provides a new strategy for the application of TiO2‐based hybrid NSs as integrated efficient nanoscale white light sources.

Plasmonic silver loaded anatase titanium dioxide nanospheres photoanode for dye-sensitized solar cell

Silver (Ag) loaded TiO2 nanospheres (Ag-TiO2 NS) are synthesized by a combination of solvothermal and chemical reduction routes and characterized by FESEM, HRTEM, EDAX, UV–Vis DRS, XRD and PL techniques. The Ag-TiO2 NS have exhibited strong light absorption and better dye adsorption. The dye-sensitized solar cell (DSSC) performance of pristine TiO2 NS and Ag-TiO2 NS photoanodes is examined under artificial light illumination. The DSSC with 2 wt% loaded Ag-TiO2 NS photoanode has delivered PCE of 6.04 % with short-circuit photocurrent density of 13.56 mA cm−2 and open circuit voltage of 0.75 V that is ∼43 % greater over the PCE of DSSC containing pristine TiO2 NS photoanode (4.16 %). This boosted performance can be accredited to visible light harvesting and fast photogenerated electrons transfer facilitated by the plasmonic Ag.

Titania Nanosheet as a Matrix for Surface-Assisted Laser Desorption/Ionization Mass Spectrometry Analysis and Imaging.

Surface-assisted laser desorption/ionization (SALDI) acts as a soft desorption/ionization technique, which has been widely recognized in small-molecule analysis owing to eliminating the requirement of the organic matrix. Herein, titania nanosheets (TiO2 NSs) were applied as novel substrates for simultaneous analysis and imaging of low-mass molecules and lipid species. A wide variety of representative analytes containing amino acids, bases, drugs, peptides, endogenous small molecules, and saccharide-spiked urine were examined by the TiO2 NS-assisted LDI mass spectrometry (MS). Compared with conventional organic matrices and substrates [Ag nanoparticles (NPs), Au NPs, carbon nanotubes, carbon NPs, CeO2 microparticles, and P25 TiO2], the TiO2 NS-assisted LDI MS method shows higher sensitivity and less spectral interference. Repeatability was evaluated with batch-to-batch relative standard deviations for 5-hydroxytryptophan, glucose-spiked urine, and glucose with addition of internal standard, which were 17.4, 14.9, and 2.8%, respectively. The TiO2 NS-assisted LDI MS method also allows the determination of blood glucose levels in mouse serum with a linear range of 0.5-10 mM. Owing to the nanoscale size and uniform deposition of the TiO2 NS matrix, spatial distributions of 16 endogenous small molecules and 16 lipid species from the horizontal section of the mouse brain tissue can be visualized at a 50 μm spatial resolution. These successful applications confirm that the TiO2-assisted LDI MS method has promising prospects in the field of life science.

Self-assembly TiO2 nanosheets as a SALDI-TOF-MS matrix for high-throughput identification of polyfluorinated compounds in water samples

Concerns about bioaccumulation, persistence and toxicity have led to a lot of researches on perfluorinated compounds (PFCs). In order to identity PFCs in real sample, self-assembled TiO2 nanosheets (TiO2 NS) were fabricated by an one-step hydrothermal method and applied as matrix for the surface-assisted laser desorption/ionization time-of-flight mass spectrometry (SALDI-TOF MS) detection of PFCs. Compared to the commercial P25 TiO2, the proposed self-assembled TiO2 nanosheets matrix is better reproducibility and higher sensitivity benefiting from the unique hexagon structure of TiO2 NS. 22 and 12 PFCs have been detected in water samples collected from locations near the outlets of a factory and a waste-water treatment plant, respectively. The proposed method can be a promising tool for high-throughput detect of trace PFCs in real samples.

TiO2 nanosheets with exposed {001} facets co-modified by AgxAu1−x NPs and 3D ZnIn2S4 microsphere for enhanced visible light absorption and photocatalytic H2 production

A novel AgxAu1−x/ZnIn2S4/TiO2 photocatalyst with high photoactivity under visible light illumination is designed in this work, in which ZnIn2S4 displays a 3D flower-like microsphere structure, while TiO2 nanosheets with highly active {001} facets (TiO2 NS) are tightly embedded in the interspaces of ZnIn2S4 microspheres, and AgxAu1-x nanoparticles (NPs) are loaded on its surface, respectively. The exquisite design of AgxAu1−x/ZnIn2S4/TiO2 makes it possess remarkable superiority in photocatalysis. Firstly, by the dual modification of ZnIn2S4 and AgxAu1−x, the AgxAu1−x/ZnIn2S4/TiO2 displays a strong absorption in visible light region, and their absorption region can be modulated by changing the ratio of Ag and Au in AgxAu1-x nanoparticles due to the plasmon coupling effect of Ag and Au. Secondly, the high separation and transfer efficiency of photogenerated carriers is achieved in AgxAu1-x/ZnIn2S4/TiO2 by utilizing TiO2 as the electron transfer intermediary of ZnIn2S4 and AgxAu1−x. All of these make AgxAu1−x/ZnIn2S4/TiO2 exhibit an evident enhancement in the photocatalytic activity of H2 production. Significantly, the hydrogen production amount and rate of Ag0.2Au0.8/ZnIn2S4/TiO2 with 60 wt% ZIS after 10 h are 9862 μmol/g and 986.2 μmol/g/h, which is around 2098 times of pristine TiO2. The apparent quantum yield of Ag0.2Au0.8/ZnIn2S4/TiO2 after 10 h is about 1.47%. Moreover, the cycling test reveals that AgxAu1−x/ZnIn2S4/TiO2 shows the high stability in photocatalytic water spitting. Based on the characterization and photocatalytic results, the proposed photocatalytic mechanism is proposed.

Facile synthesis of thin black TiO2 − x nanosheets with enhanced lithium-storage capacity and visible light photocatalytic hydrogen production

In combination of a facile and scalable solvothermal method and solid-phase reduction reactions, a novel two-dimensional black TiO2 − x nanosheet (TiO2 − x NS) with high specific surface area of 108 m2 g−1 and nearly total solar spectral absorption capability have been successfully prepared. With careful characterizations, the novel TiO2 − x NS showed enhanced electrochemical performance and visible-light photocatalytic activity than those of their white TiO2 nanosheet (TiO2 NS) precursors. The black TiO2 − x NS electrode delivered a reversible specific capacity of 160 mA h g−1 even after cycling at 0.5 C (1 C = 190 mA h g−1) for 300 times, which was significantly higher than the corresponding white TiO2 NS electrode (104 mA h g−1). Meanwhile, the TiO2 − x NS also exhibited enhanced ability of visible-light photocatalytic hydrogen production than that of the white TiO2 NS. It is expected that making white TiO2 NS into black ones is an effective way to design the photocatalysts with visible light response and the anodes with long lifetime and high rate performance in lithium ion batteries. The novel black TiO2 − x NS could find potential applications in the field of environmental management and energy storage and conversion.

Novel Flexible Transparent Conductive Films with Enhanced Chemical and Electromechanical Sustainability: TiO2 Nanosheet-Ag Nanowire Hybrid.

Flexible transparent conductive films (TCFs) of TiO2 nanosheet (TiO2 NS) and silver nanowire (Ag NW) network hybrid were prepared through a simple and scalable solution-based process. The as-formed TiO2 NS-Ag NW hybrid TCF shows a high optical transmittance (TT: 97% (90.2% including plastic substrate)) and low sheet resistance (Rs: 40 Ω/sq). In addition, the TiO2 NS-Ag NW hybrid TCF exhibits a long-time chemical/aging and electromechanical stability. As for the chemical/aging stability, the hybrid TCF of Ag NW and TiO2 NS reveals a retained initial conductivity (ΔRs/Rs < 1%) under ambient oxidant gas over a month, superior to that of bare Ag NW (ΔRs/Rs > 4000%) or RuO2 NS-Ag NW hybrid (ΔRs/Rs > 200%). As corroborated by the density functional theory simulation, the superb chemical stability of TiO2 NS-Ag NW hybrid is attributable to the unique role of TiO2 NS as a barrier, which prevents Ag NW's chemical corrosion via the attenuated adsorption of sulfidation molecules (H2S) on TiO2 NS. With respect to the electromechanical stability, in contrast to Ag NWs (ΔR/R0 ∼ 152.9%), our hybrid TCF shows a limited increment of fractional resistivity (ΔR/R0 ∼ 14.4%) after 200 000 cycles of the 1R bending test (strain: 6.7%) owing to mechanically welded Ag NW networks by TiO2 NS. Overall, our unique hybrid of TiO2 NS and Ag NW exhibits excellent electrical/optical properties and reliable chemical/electromechanical stabilities.

Efficacy of titanium dioxide nanoparticle spray to disinfect mobile phones used by endodontist: A bacteriological study.

Aim:The objectives of this study were to determine the bacterial contamination of the mobile phones that were used by the endodontist in comparison with the general dentist and also to determine the usefulness of titanium dioxide nanospray (TiO2 NS) in mobile phone decontamination.Materials and Methods:Samples from the 60 mobile phones were taken using moist sterile swabs before, 10 min, and 1 week after the use of TiO2 NS. Before collection of the swabs, the participants' informed consent was obtained. Samples obtained were cultured on blood agar to identify bacterial isolates.Results:All 60 mobile phone cultures were found to be culture positive. There was a significant reduction in the mean number of colony-forming units after decontamination with TiO2 NS (P < 0.001).Conclusions:The results from this study showed that the mobile phones may act as an important source of nosocomial pathogens and TiO2 NS would be an effective decontaminant. Therefore, it is important for dental professionals to practice routine mobile phone disinfection protocol to reduce the chances of occurrence of nosocomial infections.

Degradation of organic pollutants by bio-inspired rectangular and hexagonal titanium dioxide nanostructures

Dyes are used in textile, printing, leather, pharmaceutical, food and cosmetic industries. Dyes add color and pattern to materials. The presence of even very low concentration of dyes/dyes degradation products in effluent is highly toxic to humans and aquatic organisms. It is important to remove these dye degradation pollutants from the industrial effluents before their disposal. In recent years nanoparticles have been used for the removal of dyes from industrial waste water. Titanium dioxide nanostructures (TiO2 NS) were synthesized via a one-step facile green process. The formation of TiO2 NS was confirmed by Fourier transform infrared (FTIR) and Raman spectroscopy. Anatase (~76%) and rutile (~24%) phases were present, as determined by X-ray diffraction (XRD) analysis. X-ray photoelectron spectroscopy (XPS) was used to study the surface oxidation states of the TiO2 NS. High resolution transmission electron microscopy (HR-TEM) images revealed that the samples had hexagonal and rectangular morphologies, with diameters of ~24–32nm. The TiO2 NS were used to evaluate the photocatalytic activities of methylene blue (MB) and malachite green (MG) dyes under UV light and in dark conditions. After 60min of UV irradiation, nearly 71% of the MB and 78% of the MG was decolorized in the presence of as-synthesized TiO2 NPs.

Calcination induced phase transformation of TiO2 nanostructures and fabricated a Schottky diode as humidity sensor based on rutile phase

The effects of annealing treatment on growth of TiO2 nanostructures (Ns) on the structural and morphological properties were studied. The phase transformation also investigated in this study. TiO2 Ns were fabricated on p-type (111)-oriented silicon substrates. Chemical bath deposition (CBD) method was employed to grow TiO2 Ns on the Si substrate at different annealing temperatures (without annealing, 350, 550, 750, and 950°C). The sample prepared at an annealing temperature of 550°C had a high crystallinity. A metal–semiconductor–metal type humidity sensor device was fabricated by depositing Pt contacts on top of the optimal sample (the sample annealed at 550°C) and the device working at room temperature, environmentally friendly features, and uncomplicated low-cost fabrication.

Construction and characterization of visible light active Pd nano-crystallite decorated and C-N-S-co-doped TiO2 nanosheet array photoelectrode for enhanced photocatalytic degradation of acetylsalicylic acid

A photo-assisted deposition technique was adopted to construct highly dispersed Pd nano-crystallites on C-N-S-co-doped TiO2 nanosheets (Pd/C-N-S-TiO2 NS) arrays photoelectrodes prepared by one-step hydrothermal synthesis. The morphology, elemental composition, crystal structure, light absorption capability and photoelectrochemical (PECH) property of as-obtained Pd/C-N-S-TiO2 NS electrodes were determined and investigated through the various characterizations. The photocatalytic (PC) and photoelectrocatalytic (PEC) activity of the Pd/C-N-S-TiO2 NS electrode was evaluated through the degradation of acetylsalicylic acid and the formation of OH radicals. Compared with pristine TiO2 NS, Pd/TiO2 NS and C-N-S-TiO2 NS, Pd/C-N-S-TiO2 NS electrode displayed greatly enhanced PC and PEC activity towards the degradation of acetylsalicylic acid under visible light (λ>420nm) or Xenon light irradiation. The synergy effect of interfacial transfer of photoinduced electrons between Pd nanoparticles and TiO2 NS as well as the external potential and intense visible light absorption induced by C, N and S co-doing promoted the effective charge separation and transfer and more visible photons to participate in the catalytic process on obtained Pd/C-N-S-TiO2 NS, which were evidenced by a series of characterizations, resulting in highly efficient and stable PC and PEC activity. Moreover, the probable visible light PEC mechanism was proposed.

A novel synthesis of Ti3+ self-doped Ag2O/TiO2 (p–n) nanoheterojunctions for enhanced visible photocatalytic activity

Monodispersed Ti3+ self-doped Ag2O/TiO2 (p–n) nanoheterojunctions (SMTNs) have been synthesized via a simple hydrothermal combined with photoreductive Ag-loading method, in which simple controlling hydrolysis of Tetrabutyl Titanate (TBOT) in acetic acid (HAc) and then followed by photoreduction of silver nanoparticles attached on TiO2 using AgNO3 as Ag source. The physical and chemical properties of SMTNs were observed by X-ray photoelectron spectroscopy (XPS) measurements, X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and UV–vis diffuse reflectance spectra (DRS). The visible light-driven photocatalytic activity of SMTNs was measured by photodegradation of rhodamine B (RhB) aqueous solution. The results showed that the SMTNs exhibited a better photocatalytic activity than that of TiO2 Ns (pure TiO2 nanospheres).

Graphene-Templated Bottom-up Fabrication of Ultralarge Binary CdS–TiO2 Nanosheets for Photocatalytic Selective Reduction

A bottom-up strategy based on graphene (GR) template is developed to synthesize free-standing TiO2 nanosheets. A cross-link of GR nanosheets and a homogeneous coating of TiO2 onto the self-assembled GR surfaces are simultaneously achieved by functionalizing the GR surface with benzyl alcohol. Followed by thermal treatment in air, the 2D TiO2 structure with ultralarge lateral size far beyond the size of original GR nanosheets (several hundred nanometers) has been built with GR as a sacrificial template. The resultant TiO2 nanosheets (TiO2–NS) are then homogeneously photodeposited with CdS nanocrystals, and thus the CdS–TiO2 composite nanosheets (CdS–TiO2–NS) are obtained. Using simulated solar light as energy source, the CdS–TiO2–NS exhibits much higher activity than that of bare TiO2–NS toward selective gas-phase reduction of CO2 and liquid-phase reduction of nitroaromatics. The improved photocatalytic activities of CdS–TiO2–NS benefits from (1) the deposition of narrow-band gap CdS can effectively extend...

Dewetted Au films form a highly active photocatalytic system on TiO2 nanotube-stumps

Highly ordered TiO2 nanotube stump-[TiO2 NS]-layers, prepared by anodization of Ti in HF/H3PO4 solutions, were used as a substrate for a thermal dewetting of Au thin films. Depending on the initial Au sputter-deposited layer thickness, various sizes and densities of gold nanoparticles [Aunp] could be obtained on the TiO2 NS. Under certain conditions, very homogeneously distributed Aunp (with diameters in the range of 2–15nm) can be generated. Such Aunp/TiO2 NS combinations show a high efficiency for H2 production from H2O/EtOH solutions. A maximum H2 production efficiency could be obtained from a 2nm thick Au layer (57.03μl H2 for 9h) that was dewetted to ≈28,000particles/μm2 with individual particle diameters of ≈5nm.