Nano

Graphene is a promising alternative to indium tin oxide for use in transparent conducting electrodes. We review recent progress in production methods of graphene and its applications in optoelectronic devices such as touch panel screens, organic photovoltaic cells, organic light emitting diodes and thin film transistors. In addition, we discuss important criteria such as optical transmittance, electrical conductivity and work function, which are critical considerations in the integration of graphene conductive films with optoelectronic devices.

Photocatalytic activity can be improved through modified morphology and structure. Sodium tantalate (NaTaO₃) as a semiconductor photocatalyst is extensively used for photocatalytic water splitting. A novel electrochemical route was developed for preparing NaTaO₃ spheres. The method can easily and fast synthesize high pure phase NaTaO₃ spheres at room temperature. The NaTaO₃ sphere structure consists of a crystalline core and an amorphous shell. After a thermal treatment, the NaTaO₃ spheres show an enhanced photoelectrochemical water splitting ability.

Graphite lubricated phenolic-based friction composites filled with nanoclay and Multiwalled carbon nanotubes (MWCNT) and reinforced with lapinus and Kevlar fibers have been successfully fabricated for evaluation of their physical, chemical, mechanical and tribological properties, respectively. The increase in nanoclay and MWCNT contents led to the increase in bulk physical properties such as void contents, ash contents, water absorption and compressibility. The impact, tensile and flexural strengths get affected deleteriously when complemented by lapinus and kevlar fibers in the composites. However, with the increase in nanoclay and MWCNT contents the μ-performance, friction fade resistance and friction recovery enhanced whereas, friction fluctuations, stability and variability coefficients have been observed to be dependent on the composition. The addition of nanoclay and MWCNT raises the disc temperature whereas wear resistance of the friction composites increases with the decreasing in nanoclay and MWCNT contents. Comprehensively, it is found that with the higher nanoclay: MWCNT ratio (i. e., 1.375:1.375 wt.%) overall frictional response (μ_p = 0.386) is enhanced, showed lowest fading (fade = 22.80%) and excellent recovery performance (recovery = 130.37%). Finally, the wear surface morphology studies have been done by using scanning electron microscope (SEM) to analyze the wear mechanisms qualitatively by understanding nature of the friction contact patches.

HCl doped polyaniline (PANI) and Ru (III) doped polyaniline (Ru/PANI) have been successfully prepared by in situ oxidative polymerization method and the effect of transition metal incorporation in PANI backbone is investigated thoroughly by the execution of Fourier transform infrared spectroscopy (FT-IR) and Raman study. Moreover, to examine the change in surface and bulk morphology of the composites, the field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) have also been carried out, which revealed the agglomerated state of PANI after being Ru doped. The confirmation of the presence of Ru in the composite is achieved by the energy dispersive X-ray spectroscopy (EDS). Also, the electrochemical characterizations namely, cyclic voltammetry (CV), ac impedance spectroscopy (EIS), cyclic charge–discharge (CCD), of the composite was performed by conventional three-electrode system using 1 M H₂SO₄ electrolyte. On doping with Ru, an increment of specific capacitance of PANI from 160 F/g to 425 F/g has been achieved with a considerable increase in cycle stability.

ZSM-5 zeolites were hydrothermally synthesized in three different seeding pathways under the direction of tetrapropylammonium bromide (TPABr) template. In order to investigate the seeding effect in ZSM-5 crystallization process, ZSM-5 crystals and pre-fabricated MFI-type nanoseeds were added into the original self-induction system, respectively. The final ZSM-5 zeolites were systematically investigated based on XRD (X-ray diffraction), SEM (scanning electron micrograph), TEM (transmission electron micrograph), nitrogen adsorption characterizations and NH₃-TPD (ammonia-temperature programmed desorption). The self-induction system produced ca. 20 μm ZSM-5 zeolite displaying hexagonally uniform prisms. After the addition of ZSM-5 crystal seeds, the crystal sizes were decreased greatly to ca. 5 μm. When MFI-type nanoseeds were adopted, irregular aggregate particles consisting of 20–50 nm primary particles were rapidly synthesized. The varied hydrothermal crystallization kinetics of the three synthesis system was also explored. Adjusting the seed agents alone, ZSM-5 crystals with diverse structural, morphological, textural and hydrothermal behaviors could be fabricated conveniently. The three ZSM-5 zeolites loaded by 0.05 wt.% Pt were assessed for the xylene isomerization reaction to investigate the particle size effect on the catalytic properties.

Carbon thin films were obtained on strontium titanate (SrTiO₃) substrates using the thermionic vacuum arc (TVA) method. TVA is a different, cheap and fast technology for thin film production. The films were produced with filament current of 22 amperes from a high purity graphite rod. The crystal structure and surface morphology of the thin films were investigated by X-ray diffraction (XRD) and atomic force microscopy (AFM), respectively. In this way, microstructural characterization, surface topography, nanomechanical properties (nanohardness and adhesion force) and reflective properties of the carbon thin films produced on SrTiO₃ (100), (110) and (111) substrates were determined. Deposited carbon thin films on different orientated SrTiO₃ substrates are in polycrystalline structures. Hardness of the carbon thin films has been measured in approximately 40 GPa. This hardness value is in the range of excellent hardness region. According to reflection analysis, the film is antireflective.

A general and reliable method has been developed to functionalize either the iron oxide or the silicon nanowires (NWs) with nickel–nitriloacetic acid (Ni–NTA) complex, which was manufactured to manipulate His-tagged proteins and enzymes. The Ni–NTA-functionalized sea-urchin-shaped α-Fe₂O₃ NWs exhibit the superior protein purification efficiency and excellent stability in the form of dry powder. Application of this new nanotechnology in biomedical research field has been explored. A glucose degradation bio-matrix was made via the Ni–NTA-modified silicon NW-chips, which were conjugated with an enzyme essential to glycolysis. The glucose level in a simulated blood solution was found to be reduced from 14.4 mM to 9 mM after incubating the hexokinase I-functionalized silicon NW-chips for 12 h. These results suggest a possible way to build up a medical device using enzymes functionalized NW-chips for the removal of excess blood glucose.

This paper discusses the function of hydrogen peroxide and trisodium citrate (TSC) in the synthesis of silver (Ag) nanoplates through a simple chemical reduction method in ambient conditions. By this method, high purity Ag nanoplates were successfully generated (up to 100%). It was found that the amounts of hydrogen peroxide and TSC added to the solution are key to controlling the shape of Ag nanoparticles from spherical nanoparticles to hexagonal nanoplates and triangular nanoplates, depending on the Ag-to-hydrogen peroxide ratio and the Ag-to-TSC ratio used. This unique shape evolution process was carefully followed by a combination of ultraviolet-visible (UV-Vis) spectroscopy and transmission electron microscopy (TEM). The mean edge length of the triangular nanoplates varies from 65 nm to 100 nm. Polyvinyl pyrrolidone (PVP) is shown to increase the in-plane dimensions of the nanoplates as its relative concentration to Ag increases.

Cadmium telluride quantum dots (QDs) have received significant attention in biomedical research because of their potential in drug delivery. In this study, the chemotherapeutic agent Verbascoside (VB) was immobilized successfully onto CdTe QDs by covalent bonding between the –OH group of VB and the –COOH group of CdTe QDs. The amount of VB that could be immobilized depended on the concentration of –COOH groups (succinic acid) on the surface of the CdTe QDs. Apoptotic staining, DNA fragmentation and flow cytometry analysis further demonstrated that compared with CdTe QDs or VB treatment alone, the apoptosis rate increased after the treatment of CdTe QDs together with VB (VB–QDs) in HepG2/ADM cells. We observed that VB–QDs treatment could clearly activate apoptosis-related Caspase 3 expression in HepG2/ADM cells. Moreover, our in vivo study indicated that the treatment of VB–QDs effectively inhibited the human hepatoma HepG2/ADM nude mice tumor growth. The increased cell apoptosis rate was closely correlated with the enhanced inhibition of tumor growth in the studied animals. Thus, VB–QDs may serve as a possible alternative for therapeutic approaches for some cancer treatments. In summary, studies have shown that cancer cells are treated by the presence of VB–QDs nanoparticles based on analysis of cell apoptosis.

GO/Cu₂O nanocomposite had been successfully synthesized by electrostatic interactions method. X-ray powder diffraction (XRD), transmission electron microscope (TEM), selective-area electron diffraction (SAED), Fourier transform infrared spectroscopy (FT-IR) and Raman spectra confirmed the structure of the Cu₂O and GO/Cu₂O nanocomposite. The catalytic degradation of Rhodamine B under the condition of ultrasound was investigated and the result of UV-Vis spectroscopy demonstrated that the nanocomposite can efficiently degraded it.

Electrospun TiO₂ nanofibers were synthesized by optimizing various electrospinning conditions. The effect of the precursor's concentration present in sol used for electrospinning was studied for the performance of hybrid photovoltaic devices. The synthesized nanofibers were characterized by XRD and UV-Vis absorption spectroscopy and morphology of the fibers were investigated by FE-SEM. The surface of fibers was modified, and these modified fibers were applied to P3HT/TiO₂/ N719 composite nanofibers photovoltaic devices. The device performance was investigated by analysis of the incident photon to current conversion efficiency and a J–V characteristic under 1. 5G illuminations, which show that efficiency of the devices, can be improved from 0.13% to 0.83% by introducing TiO₂ nanofibers synthesized by optimum precursor's concentration.

Graphene oxide nanosheet is an ideal platform to capture nanoparticles for highly efficient catalysis, electrochemical sensing and biosensing. In this work, we have described a simple synthesis method for preparation graphene oxide–Au nanohybrid. Au nanodots with an average size of 1.6 nm uniformly dispersed on the surface of graphene oxide. The well-defined nanostructure has been characterized by transmission electron microscopy (TEM) and atomic force microscopy (AFM). The nanohybrid also exhibits enhanced catalytic activity toward the reduction of 4-nitrophenol by NaBH₄. Comparing with pure Au nanodots and graphene oxide, graphene oxide–Au nanohybrid shows the highest catalytic activity. This approach not only suggests a wide potential application of graphene oxide nanosheet as a host material for supporting a variety of nanoparticles, but also provides a new approach for the fabrication of graphene-based nanohybrids with multiple physical and chemical properties.