Nano

In this 21th century, the demand for glucose sensors in monitoring diabetes reaches a year-on-year peak due to the unhealthy lifestyle of society. Therefore, it is the utmost important task for scientists and researchers to develop a highly efficient and effective glucose sensor. However, conventional enzymatic glucose sensors have showed some drawbacks and the underlying issues faced by enzymatic glucose sensors are outlined in this paper. With the tremendous advancement of science and technology, the field of diabetes monitoring has evolved from enzymatic to nonenzymatic glucose sensor that heavily emphasized on the usage of nanomaterial. This transformation is supported by various justifications such as a better stability of nonenzymatic sensors towards the surrounding, higher sensitivity and ease of fabrication. Numerous materials including graphene, noble metals, (transition) metal oxides and composites have been explored for its potential in the development and performance improvement of nonenzymatic glucose sensors. This paper reviewed nonenzymatic glucose sensors, their mechanism of glucose oxidation and various promising graphene-based nanocomposite systems as well as the challenges and future perspectives of glucose biosensors.

The next generation of artificial intelligence systems is generally governed by a new electronic element called memristor. Memristor-based computational system is responsible for confronting memory wall issues in conventional system architecture in the big data era. Complementary Metal Oxide Semiconductor (CMOS) compatibility, nonvolatility and scalability are the important properties of memristor for designing such computing architecture. However, some of the concerns, such as analogue switching and stochasticity, need to be addressed for the use of memristor in novel architecture. Here, we reviewed a number of important scientific works on memristor materials, electrical performance and their integration. In addition, strategies to address the challenges of memristor integration in neuromorphic computing are also being investigated.

Enoxacin, as the broad-spectrum antibacterial activity antibiotics, has been widely used in treatment of bacterial diseases in animals and humans around the world. The extensive use of enoxacin in healthcare has also caused increasingly serious environmental risk as a matter of course. In this work, enoxacin imprinted poly (vinylidene fluoride) (PVDF) composite membranes (EIPCMs) were developed by strategy of surface grafting beta-cyclodextrin ($\beta$-CD) for the improved hydrophilic and antifouling properties of the basal membrane. PVDF membrane was prepared by phase inversion method, and $\beta$-CD was grafted onto the surface after hydroxyl groups modification. The effects of adding amount of $\beta$-CD on performance of basal membranes were systematically examined. Further, the specific recognition sites were fabricated via sol–gel surface imprinting method using 3-aminopropyltriethoxysilane (APTES) and tetraethoxysilane (TEOS) as functional monomer and cross-linker, respectively. The specific adsorption and permeation experiments were investigated and explored the separation performance and mechanism of EIPCM. The results indicated that the as-prepared EIPCMs not only exhibited highly favorable features and high rebinding strength (31.25mg g${}^{-1})$, but also possessed superior selective performance toward enoxacin (imprinted factor $\beta$ is 3.15). Furthermore, in order to investigate the practical applications of EIPCMs, the adsorption experiments were carried out using environmental sewage. The work developed here shows great potential for further applications in selective recognition and separation antibiotics pollution from the environment.

A subtle modification of the device surface is able to reduce optical loss and to further achieve high photoelectric conversion efficiency for thin film solar cells. This work shows the manipulation properties of subwavelength periodic structures on incident light at air/glass surface. In order to explore the mechanisms of optical loss, the spectral response and energy distribution of light are investigated by using rigorous coupled wave analysis and finite difference time domain methods. Calculation results show that the diffraction scattering and gradient refraction index play a significant role for better photon harvesting. With an optimized design of $P=270$nm, $f=0.35$, and hemispherical shape structure, obvious improvement in transmittance, external quantum efficiency and photo-generated current is achieved. The photoelectric conversion efficiencies of amorphous silicon thin film cells with an absorbing layer thickness of 400nm is 8.04%, improved by 5.9% compared with the flat cell of equivalent size.

Nano-hydroxyapatite crystals of different morphologies were synthesized by adding two types of amino acids (glycine and arginine) under hydrothermal conditions. The XRD, FTIR, and TEM characterizations of samples showed that the final product was pure hydroxyapatite with high crystallinity. Organic small-molecule amino acids exhibited a significant inhibitory effect on crystal growth during the synthesis process. This regulatory effect is related to the side chains of amino acids. The results of co-culturing with bone mesenchymal stem cells showed that the cell compatibility of nanoparticles differs based on their morphologies. The results of this study are significant for the fabrication of nano-hydroxyapatite with tunable morphology, which can have applications in the fields of bone repair and drug loading.

A composite of methylammonium lead iodide perovskite (MAPbI${}_3)$ and carbon dots is prepared under ultrasound irradiation. Characterizations of X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, transmission electron microscopy, emission field scanning electron microscopy, Raman spectra and UV-Vis diffuse reflectance spectroscopy are performed. Excellent photoelectrochemical properties of prepared composites are examined by a collection of measurements including photocurrent density, open-circuit potential, current–voltage curves, cyclic voltammetry curves and Nyquist plots. The results imply that the as-prepared composites exhibit better electrochemical and photoelectrochemical properties as well as stability than those of blank MAPbI₃. The improved properties are due to the formed Pb–O–C bridge bonds in the composites, which can promote the generation and transport of charge carriers. This work provides a novel sonochemical synthesis strategy and investigation on the photoelectrochemical performance of MAPbI₃/carbon dots composites.

Copper-palladium (CuPd)/boron nitride nanosheet (BNNS) nanocatalysts were successfully prepared by a microwave-assisted method by using BNNSs as a carrier. These catalysts with a low noble metal content had a high catalytic activity for Cr(VI) reduction at room temperature. The reaction rate reached 0.04044s${}^{-1}$, which was approximately 2.5 times that of Cu₈Pd₂/rGO with the same metal loading amount. Compared with the previously reported PdCu/NG nanocatalysts with a high noble metal content, the reaction rate increased more than five times. This is of great significance to the application of supported metal composites in environmental catalysis. The structure and morphology of the catalyst was characterized by means of X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM). Several types of control experiments showed that the catalytic activity of the catalysts was not only influenced by the synergistic effect of bimetallic CuPd and metal-BNNSs but also related to the catalytic effect of the BNNS carrier itself.

In this work, graphene aerogels (GAs) with three-dimensional interconnected networks were prepared by chemical reduction and self-assembly of graphene oxide sheets. After microwave treatment, obtained microwave reduced graphene aerogels (MRGAs) were used in the preparation of bismaleimide (BMI) composites. The results show that the microwave treatment significantly enhanced the quality of GAs, and the three-dimensional networks in the GAs were well retained. Moreover, the MRGAs were highly efficient in endowing BMI with high electrical conductivity and excellent electromagnetic interference shielding effectiveness (EMI SE). The conductivity of MRGA/BMI composites was 42–68% higher than that of GA/BMI composites. When the filler content is 1.6 wt.%, the EMI SE of MRGA/BMI composite was 32.3% higher than that of GA/BMI composite in the X band.

Developing nonmetal-doped mesoporous TiO₂ is highly attractive for preparing semiconductor visible photocatalyst with high activities. Here, we prepare N/F co-doped mesoporous TiO₂ with high vis-photocatalytic activities by a simple liquid phase deposition process followed by annealing in air using C${}_{16}$TAB as a bi-functional template (forming mesoporous and providing dopants). N₂ adsorption isotherms, low-angle X-ray diffraction (XRD) and transmission electron microscopy (TEM) indicate the formation of wormhole-like mesoporous structure. Wide-angle XRD and high-resolution TEM demonstrate the presence of anatase TiO₂ mesopore wall. XPS analyses reveal that N is doped into TiO₂ lattice in the forms of substitutional and interstitial N species, and that F is doped into the TiO₂ lattice in the form of interstitial F. The mesopore-forming and doping mechanisms are thoroughly discussed based on the bi-function of C${}_{16}$TAB template. Mesoporous structure results in a high BET surface area of TiO₂. High-concentration nitrogen species in anatase lattice and mesoporous structure remarkably increase the visible absorption of TiO₂. As a result, the reaction rate constant of MB degradation catalyzed by N/F co-doped mesoporous TiO₂ photocatalysts is about 7 times that by P25.

Organic transistors are crucial components in future flexible electronics due to their excellent properties and ease of circuit integration. Previously, we demonstrated that flexible organic (polyimide) thermal transistors could be prepared using commercial graphite paper as the substrate. These materials exhibited excellent temperature sensitivity, linearity and recoverability due to the intrinsically high thermal conductivity of graphite. In this study, boron nitride (BN) sheets/polyimide hybrid dielectric layers were synthesized for the fabrication of flexible organic transistors using a commercial graphite paper. Under test, the results showed that the introduction of BN sheets was beneficial in improving the mobility and transistor characteristics of the device, as well as enhancing the overall stability. The as-fabricated transistors virtually exhibited no hysteresis at all BN contents.

In this work, the function of 4-nitroimidazole (4-NIm) in the formation of Cr-MIL-101 was confirmed. It was found that 4-NIm is an effective additive in the formation of Cr-MIL-101 synthesized at lower temperature. The investigation of crystallization time showed that 4-NIm can prevent Cr-MIL-101 phase converting into Cr-MIL-53 phase. The effect of concentration of 4-NIm on the morphology and the yield of Cr-MIL-101 may therefore be explained by increasing the nucleation rate. The investigation of crystallization temperature revealed that 4-NIm changes the synthesis temperature range of Cr-MIL-101 into 423–463 K. The assistant function of 4-NIm was played through interaction with H${}^{+}$ and NO${}^{3-}$ in the synthesis system, which may lead to enhancement of the deprotonation of H₂BDC.

The development of low-cost, high-purity and high-performance porous carbon is of great significance for promoting the commercial application of supercapacitors. In this paper, porous carbon spheres (PCSs) with excellent electrochemical performance were obtained by carbonization and activation of starch gel spheres as precursor which is prepared by microemulsion process. The obtained PCSs exhibit both microporous and mesoporous structure, showing a large specific surface area of 1117.0 m² g${}^{-1}$ and exhibiting a high specific capacitance of 221.3 F g${}^{-1}$at a current density of 0.5 A g${}^{-1}$ in aqueous electrolyte (and still displays capacity of 146.0 F g${}^{-1}$ in ion liquid electrolyte). The PCSs//PCSs symmetric supercapacitor (SSC) based on aqueous electrolyte exhibits an energy density of 10.9 Wh kg${}^{-1}$ at a power density of 300.0 W kg${}^{-1}$, whereas that based on ion liquid electrolyte achieves a high energy density of 29.0 Wh kg${}^{-1}$ at 650.0 W kg${}^{-1}$. The study provides a new idea to develop low-cost, high-purity and high-performance porous carbon materials for supercapacitors.

Solid-state nanopores have shown great potential in investigating salinity gradient energy generation as a renewable power generator. In this work, various diameter silicon nitride (Si₃N${}_4)$ nanopores were fabricated to investigate the power generation between two potassium chloride solutions with different concentration gradient ratios by reverse electrodialysis. The maximal estimated power density of a Si₃N₄ nanopore measured experimentally can be high to 16649Wm${}^{-2}$. To compare with the single Si₃N₄ nanopore, multiple nanopores array has also been investigated. The equivalent circuit model of multiple Si₃N₄ nanopores array generator is quantitatively constructed by massive reproducible experimental data and theoretical derivation. For nanopore array, the osmotic current basically keep a linear growth with the number of the nanopores at every concentration ratio. While, the osmotic voltage is basically independent on the number of nanopore. The power generation circuit of the nanopore array can be regarded as a parallel circuit of multiple nanopores. Power generation from concentration gradients in Si₃N₄ nanopores could be widely used in a variety of applications like ultra-low power devices and micro-nano electromechanical systems.

Silicon carbon nanoparticles (SCNPs) coated with reduced graphene oxide (rGO) were fabricated by a hydrothermal method and subsequently by a simple heat treatment process. SCNPs/rGO exhibit excellent electrochemical performance which not only attributes the rGO layer to inhibit the volumetric expansion of silicon and reduce the impedance between the active material and lithium ions during the electrochemical process, but also improves the electrical conductivity of SCNPs/rGO. The as-prepared compound was cyclically tested at a current density of 150mA/g, with the first charge and discharge capacities of 3152.2mAh/g and 3342.7mAh/g, respectively. Moreover, the electrochemical performance of SCNPs/rGO was better than SCNPs. The $R_{\mathrm{\text{CT}}}$ values for fresh battery, after 1 cycle and 100 cycles, are 120.9$\mathrm{\Omega }$, 120.5$\mathrm{\Omega }$ and 104$\mathrm{\Omega }$. Thus, compared with SCNPs, SCNPs/rGO exhibited lower overall impedance values. These results indicate that the addition of graphene layer significantly improved the electrochemical performance of SCNPs electrodes and reduced the internal resistance of the battery.