Nano

With the development of society, oil pollution has become more and more serious, it is becoming a global issue to separate oil and water mixture. Currently, a variety of functional materials have been successfully prepared for oil/water separation. Among them, polyurethane is an attractive candidate due to its low cost, wear-resistance and excellent mechanical properties. This report summarizes the design strategy of polyurethane-based materials and their applications in oil/water separation. The progress made so far will guide further development of polyurethane-based materials for oil/water separation.

Micro-porous activated carbons (ACs) with a narrow pore size distribution of 0.4–0.6nm and high specific surface areas (1160–1315m²$\cdot$ g${}^{-1})$ are prepared from environment-friendly, low-grade potassium humate (HA-K, carbon resource) and mild activating agent potassium acetate (CH₃COOK). Microstructure characterizations indicate that the introduction of activating agent CH₃COOK is a key step to achieve high specific surface area and carbonization degree. These ACs contain small amount of oxygen and nitrogen, and show obvious pseudo-capacitance besides double layer capacitance. As a result, the optimized ACs achieve high specific capacitances of 311F$\cdot$g${}^{-1}$ and 317F$\cdot$g${}^{-1}$ at 0.1A$\cdot$g${}^{-1}$ in 2M KOH and 1M H₂SO₄ aqueous electrolytes, respectively. This sample also shows a good charge-discharge cycling stability within 10 000 cycles.

Fluorine-doped tungsten oxide (WO₃) plate-like films were synthesized by hydrothermal radio-frequency (RF) sputtered tungsten (W) thin films in HF solution. The crystal structure, composition and morphology of nitrogen fluorine (F) doped WO₃ were characterized by scanning electron microscope (SEM), X-ray diffractometer (XRD), X-ray photoelectron spectroscopy (XPS), and UV-Vis diffuse reflectance spectra (DRS) techniques. The results indicate that fluorine can be doped successfully into WO₃ plate-like films by hydrothermal synthesis in hydrofluoric acid (HF) solution. The F-doped WO₃ samples show stronger absorption in the UV-Vis range and a red shift in the band gap transition. Incident photon to current efficiency (IPCE) measurements carried out on photoelectrochemical cell with F-doped WO₃ plate-like films as anodes demonstrate a significant increase of photoresponse in the visible region compared with undoped WO₃. The photocatalytic activity under visible light irradiation for newly synthesized F-doped WO₃ plate-like films was investigated by degradation of methyl orange. The photocatalytic activity of F-doped WO₃ plate-like films was 3-fold enhancement compared with pure WO₃ samples.

In this work, highly active graphitic carbon nitride composite photocatalysts with an isotype heterojunction semiconductor structure have been prepared through the molecular composite precursors consisting of urea and melamine. These photocatalysts were characterized by XRD, SEM, TEM, UV-Vis, BET and transient photocurrent responses. The photodegradation of dyes in aqueous solution under visible-light irradiation has been investigated over carbon nitride photocatalysts consisting of different urea/melamine mass ratios. Further studies by photocurrent indicate that the photosynergistic effect of isotype heterojunction can remarkably enhance the photoinduced interfacial charge transfer, thereby increasing the charge separation during the photocatalytic reaction.

To address accosts of this modern age, the synthesis of metal nanoparticles is more important than ever. Copper has been recognized as a nontoxic, safe inorganic material, cheaper antibacterial/antifungal agent, and has high potential in a wide range of biological, catalytic and sensors applications more particularly in the form of nanoparticles. This resulted in the development of numerous methods for the synthesis of copper nanoparticles. As conventional methods like chemical and physical methods have several limitations so there is need to an alternate method. Due to nontoxic and eco-friendly nature, it has recently been shifted toward green synthesis of copper nanoparticles over conventional methods. Additionally, characterization of the synthesized nanoparticles is essential for their use in various applications. This review gives an overview of environment friendly synthesis method of copper nanoparticles and their applications on the basis of their potential selectivity and preferences in a number of fields like material sciences and biomedicine.

In this paper, we have reported the high sensitive UV detector using ZnO nanowires prepared on porous silicon (PS). The aligned naturally doped n-type zinc oxide (ZnO) nanowires were grown on both PS and n-Si(100) substrates to produce isotype heterojunctions using hydrothermal method. The length of the nanowires ranges 3–4$\mu$m and the diameter 150–200nm. Grown ZnO nanowires on PS substrate has lower reflectivity value compared with Si substrate. The electrical behavior of such devices has been examined at different intensities of UV radiation. The current–voltage curve of the isotype heterojunction shows rectifying behavior in a dark environment. Under UV light, the current was increased by using PS instead of n-Si under reverse bias. The I–V characteristics of the device show a significant rise in the current for low intensity of UV radiation evidencing the high sensitivity of the reported structure. The sensitivity for such devices is obtained, $2.2\times 10^3,0.47\times 10^3$ and $0.21\times 10^3$ at UV radiation of 1.5mW/cm² intensity at bias voltage of −0.75 V for three proposed structures. The samples have been analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM) to investigate their structures and geometries.

Computer simulation is carried out for investigating the effect of nanoparticles on diblock copolymer morphology under cylindrical confinement. The phase diagrams of polymer nanocomposites with nanoparticle-block wetting strength and concentration of nanoparticles are obtained in different nanopores. In small diameter nanopore, there is almost no influence of nanoparticles on the diblock copolymer morphology because of the stronger confinement effect; in middle diameter nanopore, the system can self-assemble into various novel structures due to the interaction between confinement effect and nanoparticles effect; in large diameter nanopore, due to the stronger effect of nanoparticles, a disorder-order-disorder phase transition occurs with the wetting strength and concentration of nanoparticles increasing. This result can be useful in designing new nanocomposites with advanced electrical conductivity and/or mechanical strength.

A highly sensitive and selective biomimetic sensor based on zinc porphyrin molecularly imprinted Polymer microspheres (MIPMs), gold nanoparticles (AuNPs) and carboxyl graphene (CG) nanomaterials was successfully developed for direct electrochemical detection of methyl parathion (MP). The novel strategy emphasized the fabrication of a porphyrin zinc-based sensor via attaching MIPMs on AuNPs/CG nanocomposites. MIPMs was prepared by free radical polymerization using MP as the template, Zinc porphyrin as the functional monomer, ethylene glycol dimethacrylate (EGDMA) as the cross-linking reagent and azobisisobutyronitrile (AIBN) as the initiator. The introduction of AuNPs/CG significantly increased the effective electrode area, and amplified the sensor signal. The modified electrode was characterized by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The parameters of the detection process were also optimized. The biomimetic sensor exhibits a much wider linear dynamic range between 1.0$\times$10${}^{-6}$mol L${}^{-1}$ and 8.0$\times$10${}^{-9}$mol L${}^{-1}$ and the limit of detection (LOD) down to 3.16$\times$10${}^{-10}$mol L${}^{-1}$ based on S/N $=$ 3. The sensor had good reproducibility, stability and selectivity for MP detection. The developed sensor was successfully employed for the detection of MP in real samples.

Conductive polyaniline/CeO₂ nanocomposite powders (PANI/CeO${}_2)$ were prepared by an in situ polymerization method. The effects of CeO₂ content on the microwave absorption properties of composites were investigated. The phase composition, morphological characteristics, electromagnetic parameters and microwave absorption properties of the composites were characterized through X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy and vector network analysis. Results show that CeO₂ nanorods are coated with PANI to form a well-defined hierarchical structure. CeO₂ is well-incorporated into the PANI matrix. CeO₂/PANI exhibits excellent microwave absorption properties at 2–18GHz. As the CeO₂ content increases to 30wt.%, an optimal reflection loss (RL) of $-$40dB (99.99% of electromagnetic wave absorption) is observed at 8.8GHz with a thickness of 3.0mm. The frequency bandwidth corresponding to 90% of electromagnetic wave absorption crosses the X-band. Therefore, PANI/CeO₂ can be used as an advantageous candidate for a new type of microwave absorptive material.

Highly dispersed Mn-Fe mixed metal oxides were supported on the nitric vapor functionalized carbon nanotubes (CNTs) by the polyol process for the low-temperature selective catalytic reduction (SCR) of NO with NH₃. X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), H₂ temperature-programmed reduction (H₂-TPR) and Fourier transform infrared (FT-IR) spectroscopy have been used to elucidate the structure and surface properties of the obtained catalysts. It was found that the Mn-Fe/VF-CNTs catalysts synthesized by the polyol process exhibited higher activity and more extensive operating-temperature window, compared to the catalysts prepared by the impregnation method. On the basis of the catalyst characterization, the better dispersion of metal oxides on the CNTs surface, the more chemisorbed oxygen species, the higher Mn${}^{4+}$/Mn and O${}_{\alpha }$/O${}_{\alpha }+$O${}_{\beta }$ ratios played key roles in the excellent catalytic performance of the catalyst in the low-temperature SCR of NO to N₂ with NH₃.

In this work, nano-convex-patterned polyimide surface (notated as 1-sample) and nano-concave-patterned polyimide surface (notated as 2-sample) were prepared by self-assembly and etching. Atomic force microscope (AFM) with a colloidal probe was used to examine the adhesion and nano-tribological behavior of the 1-sample and 2-sample. Results suggest that the 1-sample and 2-sample can decrease the surface friction and adhesive forces because of the decreased contact area between the contacting pairs. The friction forces of the 1-sample and 2-sample increased with the increase in sliding velocity and applied load. Moreover, the nano-concave pattern is more effective in reducing the adhesive force than the nano-convex pattern because of its higher surface roughness. However, the nano-convex patterning is more effective in reducing the friction force than the nano-concave patterning because of the smaller area of contact between the 2-sample and the colloidal probe.

In this paper, a novel colorimetric biosensor for Hg${}^{2+}$ is presented based on Hg${}^{2+}$ stimulated peroxidase-like activity of hollow porous gold nanoparticles (HPGNPs). Under mild conditions, HPGNPs show high catalytic activity toward the oxidation of 3, 3${}^{\prime }$, 5, 5${}^{\prime }$-tetramethylbenzidine (TMB) using H₂O₂ as an oxidant. The peroxidase-like activity of HPGNPs is “switched-on” selectively in the presence of Hg${}^{2+}$, which permitted a novel and facile colorimetric sensor for Hg${}^{2+}$. This method exhibits many merits like high selectivity and sensitivity. As low as 18.5nM Hg${}^{2+}$ could be determined at a linear range from $0.5\times 10^{-6}$M to $50\times 10^{-6}$M. This method is successfully applied for the determination of total mercury content in tap water and Yellow River which indicates that the method has a great potential for the routine determination of Hg${}^{2+}$ in environmental samples.

Pre-lithiated multiwalled carbon nanotube anode was prepared by internal short circuit approach(ISC) for 5min, 30min, 60min and 120min respectively. Lithium ion capacitors (LICs) were assembled by using pre-lithiated multiwalled carbon nanotubes as anodes and activated carbon (AC) as cathodes. The structure of multiwalled carbon nanotubes and electrodes were investigated by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The electrochemical performance of pre-lithiated multiwalled carbon nanotube electrodes and pristine carbon nanotube electrodes were tested by galvanostatic charge/discharge and electrochemical impedance. The results indicated that pre-lithiation carbon nanotubes greatly improved the charge/discharge performance of LICs. The energy density was four times than conventional electric double-layer capacitors (EDLCs) at the current density of 100mA/g. The LICs achieved a specific capacitance of 59.3F/g at the current density of 100mA/g with 60min pre-lithiatiation process. The maximum energy density and power density was 96Wh/kg and 4035W/kg, respectively. The energy density still remained about 89.0% after 1000 cycles. The LIC showed excellent supercapacitor performance.