Nano

A new type of pure organic 5,10,15,20-tetra (4-hydroxyphenyl) porphyrin (TPPH)/$g$-C₃N₄ nanohybrid was prepared to expand the light absorption range of graphitic carbon nitride materials. The morphology and structure of the composites were systematically characterized by scanning electron microscope, transmission electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy. Results show that after the introduction of TPPH, the visible light area optical absorption of the composite sample increased significantly under the noncovalent interaction of TPPH and $g$-C₃N₄, and the electrochemical impedance spectroscopy and $I$–$T$ measurements confirmed the improved charge separation efficiency of the sample and showed excellent photocatalytic hydrogen production capacity. Under full spectrum irradiation, the hydrogen production of 1.67% TPPH/$g$-C₃N₄ without adding co-catalyst reached 10.87mmol$\cdot {\mathrm{\text{g}}}^{-1}\cdot {\mathrm{\text{h}}}^{-1}$, about 2.68 times that of pure $g$-C₃N₄ (4.06mmol$\cdot {\text{g}}^{-1}\cdot {\mathrm{\text{h}}}^{-1}$), which showed effective promotion of the electron transfer between TPPH and $g$-C₃N₄.

In this paper, a new hydrogen peroxide electrochemical sensor based on the synergistic modification of nitrogen-doped porous carbon (NPC) and carbon nanohybrid aerogel (CNA) is proposed. NPC has been successfully synthesized from porous polyacrylonitrile (PAN) precursor by pre-oxidation to obtain adequate pyridinic-N, which contributes to enhance the electrocatalytic activity. Simultaneously, CNA has been also prepared by self-assembly in a hydrothermal environment without any interference followed by vacuum freeze drying. The final products were characterized by diversiform techniques including scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and X-ray powder diffraction (XRD). The results showed that the NPC with 23.18% pyridinic-N exhibited well-defined and interconnected three-dimensional (3D) porous microstructure and CNA which encapsulates $\gamma$-Fe₂O₃ particles was obtained. The sensor fabricated by NPC and CNA delivered a wide linear range from 60$\mu$M to 1680$\mu$M ($R^2=0.994$) and 1680$\mu$M to 3335$\mu$M ($R^2=0.998$) with sensitivities of 3.98$\mu$A mM${}^{-1}$ and 5.56$\mu$A mM${}^{-1}$, respectively. Furthermore, the obtained sensor showed low detection limit (4.478$\mu$M, $S$/$N=3$), good selectivity and repeatability, rapid response and satisfying practicability.

Li-rich layered oxides (LrLOs) attracted much attention due to their high specific capacity. However, LrLOs have disadvantages such as fast voltage decay and poor cycle stability. In this work, we propose a dual-doping strategy based on Ce and F ions to respond to the defects of LrLOs. This work shows that Ce and F have a strong synergistic effect in LrLOs cathode materials. Dual-doping makes the structure of the cathode materials more stable, which is mainly manifested by inhibiting the extraction of lattice oxygen, reducing the migration of cations during the cycle, and reducing the corrosion of the electrolyte to the cathode materials. Thereby, the work improves the cycle performance of the cathode materials. The capacity retention rate is 84.3% for 200 cycles at 1C (versus 59.6%). The median discharge voltage is 3.2155V after 200 cycles at 1C (versus 2.9485V). The voltage decay is 0.4706V for 200 cycles at 1C (versus 0.6923V). Interestingly, our research found that Ni${}^{2+}$ of the Li layer also plays an important role in the process of improving cycle performance. This work provides new ideas for solving the cycle stability of LrLOs cathode materials and suppressing voltage decay.

In this paper, the impact of the crystallite sizes of nickel oxide nanoparticles (NiO NPs) on their efficiency for electrochemical capacitors (EC) has been investigated. NiO NPs were prepared without and with low and high concentrations (0.02M and 0.1M) of cetyltrimethylammonium bromide (CTAB) using the hydrothermal process that represent NiO, NiO-1, NiO-2, respectively. The crystallite size of NiO, NiO-1, NiO-2 NPs was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM) analysis. The thermogravimetry/differential thermal analysis (TG/DTA) was used to investigate the thermal observation of as-prepared precursor to transform as NiO NPs. HRTEM revealed spherical seed-like morphologies, which consist of aggregated NiO-1 NPs with an average particle size of 9nm. The NiO-1 shows the large specific capacitance value of 168Fg${}^{-1}$ at a current density of 0.5Ag${}^{-1}$ compared with other NiO and NiO-2 NPs. The study suggests that the low concentration of surfactant CTAB of NiO NPs plays an important role in supercapacitor applications because of the smaller crystallite sizes of the materials as well as a large number of active sites for faradic reaction.

The development of a highly sensitive and selective electrocatalyst for the detection of diclofenac sodium (D.S.) has remained a great challenge. In this work, graphene oxide functionalized with silver nanoparticles and zinc oxide (Ag–ZnO–GO) electrocatalyst was developed and investigated for the detection of D.S. The Ag–ZnO–GO/glassy carbon electrode exhibits high sensitivity and fast response within 3s owing to the efficient oxidation of D.S. at a very low potential at 0.25V. Moreover, the electrode shows a low detection limit of 0.02$\mu$M ($S∕N=3$) and long-term stability. To explore the synergic effects, the measurements of D.S. using GO, ZnO and ZnO–GO modified electrodes were also performed. The results demonstrate that the Ag–ZnO–GO nanocomposite electrode exhibits enhanced sensitivity and selectivity compared to the other electrodes. In addition, the electrode reveals excellent results for D.S. detection in the real samples as well. The enhanced performance of the proposed electrode is attributed to the improved electron transfer ability and synergic effects of the plasmonic Ag NPs and ZnO–GO structure. It is expected that Ag–ZnO–GO composite is a promising candidate for the construction of cost-effective electrochemical biosensors for medical and industrial applications.

As a model of neurodegenerative disease, the study on SH-SY5Y cells is of great significance due to the complexity of cause and difficulty in cure. Based on this reality, we studied the influence of culture duration on the morphology and mechanical properties of living SH-SY5Y cells by atomic force microscopy (AFM). A comparative analysis was made to characterize the cell size and tip-cell adhesion, and their increased trends with the increase of cell culture duration were obtained, providing a guideline for the physiological characteristics of the cells. As the culture time increased from 24h to 48h, the measured average height and width of cells were increased by 0.59$\mu$m and 1.38$\mu$m, respectively. As for cell elasticity, statistical analysis showed that the difference between different parts of the cell was obvious. Additionally, the electrophysiological characteristic as an important indicator for measuring the functional activities of SH-SY5Y cells was investigated. Here, a homemade conductive atomic force microscope (C-AFM) provided an effective way for membrane potential recordings. It was successfully used to study the real-time responses of living SH-SY5Y cells to mechanical insertions, and a membrane potential with an amplitude of $-0.101$V was obtained without losing cell viability.

Abundant investigators have devoted their efforts to proceed the development of novel strategies aimed at anti-tumor through regulating gene expression negatively. Flap structure-specific endonuclease 1 (FEN1) received widespread attention in becoming a potential target for breast cancer. In this study, a prominent protocol based on small molecular nucleic acids was reasonably demonstrated. Various oligonucleotides containing FEN1 cleavage site and anti-miRNA21 sequences were designed and synthesized as a kind of disturbance factor to FEN1 and miRNA21. In order to obtain an ideal therapeutic outcome, graphene oxide (GO) was also employed, which rendered the whole system with photothermal therapy (PTT) effect. Finally, a novel trinity treatment system came into being with the characteristic of combined therapy involving miRNA21 silencing, FEN1 inhibition and PTT. In short, it is our hope that the designed multifunctional system could provide a promising use for the development of anti-tumor therapy in the foreseeable future.

Three-dimensional graphene network (3DGN) and UiO-66 co-modified composite photocatalysts are prepared to decompose dye in solution. The roles of UiO-66 and 3DGN are studied based on the adsorption capacity, visible-light activity, lifetime of photo-induce electrons and electron paramagnetic resonance curves. The rates of degradation of Rhodamine-B are $1.39\times 10^{-1}$min${}^{-1}$ and $7.89\times 10^{-2}$min${}^{-1}$ under UV- and visible-light irradiation. The major function of UiO-66 is increasing the Brunner–Emmet–Teller surface area and adsorption capacity significantly, while the effect of 3DGN is playing as an electron tank and sensitizer. Moreover, the influence of mass fraction of UiO-66 on the resulting photocatalytic performances is revealed (5wt.% is found the optimized value), and the synergy is also discussed. Finally, the photocatalytic mechanisms of the resulting photocatalysts both under the UV- and visible-light irradiation are proposed.

Multifunctional composite nanostructure prepared via electrospinning has attracted wide attention. In this study, Fe₂O₃-carbon composite nanofiber with particle–nanorod structure was successfully prepared via electrospinning and followed calcination. Then, the electromagnetic properties of this material have been fully characterized, and the influence of different preparation conditions on these properties has been studied. In addition, compared to pure $\gamma$-Fe₂O₃ nanoparticles and hollow Fe₂O₃ nanofibers, the composite nanofibers with a thickness of 2.64mm exhibited an additional absorption peak at a frequency of 13.92GHz and an enhancement in absorption at a frequency of 15.45GHz, which may be attributed to the increase in electrical loss introduced by amorphous carbon and the enhanced magnetic loss resulting from the multi-stage reflection introduced by the particle–nanorod structure. This study shows that the composite of Fe₂O₃ and carbon, and the introduction of the particle–nanorod structure can improve the microwave absorption efficiency of materials, and more nanocomposites can be designed like this to further improve their electromagnetic properties and absorption efficiency in the future.

The hausmannite phase manganese oxide nanoparticles (NPs) were prepared by a simple chemical reflux method. Powder X-ray diffraction shows the well-crystalline structure of Mn₃O₄ spinel. Fourier-transform infrared spectroscopy study exhibited the Mn–O functional group vibrations in the hausmannite NPs. UV–visible spectroscopy study reveals that the optical bandgap energy of the manganese oxide nanoparticles is about 3.1eV. The scanning electron microscopy (SEM) analysis shows that the surface morphologies of the manganese oxide nanoparticles are wrinkle structures. Cyclic voltammetry studies were carried out to the electrode of Mn₃O₄ NPs in KOH and Na₂SO₄. The charge–discharge analysis and impedance spectroscopy method analysis were made on Mn₃O₄ NPs to understand the electrochemical performance. The ability of synthesized Mn₃O₄ NPs electrodes was analyzed and compared with the existing materials for the supercapacitor applications.

Interlaminar delamination and brittle fracture of matrix have been a dilemma that fiber-reinforced composites have been faced with. Herein, the polyimide (PI) nanofiber-toughened glass fiber fiber-reinforced epoxy composites were prepared by electrospinning method and subsequent vacuum assistant resin transfer molding. The effect of spinning parameters including PI concentration, applied voltage, collector distance, jet speed and ambient humidity on the resultant fiber diameter and its distribution was systematically evaluated. The surface properties of obtained PI nanofibers were characterized by FT-IR, TG-DSC and water contact angle. The effect of PI concentration on tensile strength of PI membranes was also studied. The mode I (G${}_{\mathrm{\text{Ic}}})$ and mode II (G${}_{\mathrm{\text{IIc}}})$ interlaminar fracture toughness were measured. The results indicated that G_Ic and G_IIc increased by 127.69% and 85.33%. The improvement of interlaminar fracture toughness may be attributed to the bridging effect of PI nanofibers.

The self-supporting three-dimensional (3D) nanoporous PdAg alloy (NP–PdAg) foams have been prepared by a simple one-step dealloying melt-spun Al–Pd–Ag ribbons in a 20wt.% NaOH aqueous solution at 90^∘C for 1.5h. The structure is advantageous to the diffusion and removal of the intermediate products and the transmission of the methanol molecules. The NP–PdAg foams exhibit better electrocatalytic performance than the NP-Pd foam toward the methanol oxidation in potassium hydroxide (KOH) solution. The optimal atomic ratio of Pd to Ag in the NP–PdAg foams is 1:1, and its electrocatalytic activity is about 2.6 times that of the NP–Pd foam. The significant improvement in the electrocatalytic performance is attributed to the addition of a moderate amount of Ag. In the whole electrocatalytic process, Ag can provide OH_ads to oxidize the intermediate products on the surface of active Pd sites into carbon dioxide or other cleaning products. Also, the Ag can increase electrochemical active surface area and the adsorption energy of Pd to methanol molecules and OH_ads. These significantly prevent the accumulation of poisoning intermediates on the surface of Pd and quickly release more active Pd sites.

Atomic force microscope (AFM) is a powerful nanoscale instrument, which can obtain the true surface morphology of samples. There are strict requirements for the detailed features in AFM images, so it is necessary to mine the deep information in the images. Nevertheless, the standard AFM scanning process takes a very long time to obtain high-quality images. For most cases, the original images of AFM are with low resolution. In order to get the more detailed texture and feature information as much as possible, a super-resolution convolutional neural network algorithm based on enhanced data set is proposed in AFM imaging. By learning the mapping relationship between low-resolution images and high-resolution images from the image database, the high-resolution image is finally obtained. Aiming at the problem of long scanning time and too small training database of AFM image, adaptive histogram equalization is used to expand and enhance the training set of AFM images. Compared with the traditional super-resolution methods, the subjective and objective evaluation of the reconstructed image verifies the feasibility of the proposed algorithm.