Nano

Carbon nanotubes (CNTs) were doped by ammonium borate as the sources of nitrogen and boron. Under the protection of Ar gas, boron-nitrogen doped CNTs were prepared through nitriding and boronization at high temperature. It is a conductive additive. Then, the obtained CNTs were mixed with activated carbon (AC), SP, sodium dodecyl sulfate (SDS), and cellulose fiber to prepare electrodes. With all the materials, a symmetric electric double-layer supercapacitor (EDLC) was assembled. Next, the materials and electrodes were also characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The factors, chemical connections, and specific surface area of the CNTs were analyzed by X-ray energy spectrum analysis (EDS), X-ray photoelectron spectroscopy (XPS), as well as a specific surface area and porosimetry analyzer (BET). In addition, the electrochemical performances of electric double-layer capacitors were tested with the help of cyclic voltammetry, constant-current charging and discharging, and so on. From the results, we can make a conclusion, that is, both B and N atoms were added into the CNTs and formed bonds successfully with carbon atoms mutually. Besides, the specific surface area is about 1.5 times than that of the CNT. When the charge/discharge current density reaches 50mA/g, we can find that the mass specific capacitance of the capacitor can run up to 32.19F/g. Also, we observe that the maximum power density is close to 220W/kg (700mA/g), and the energy density can arrive 9.31Wh/kg (50mA/g). Based on the impedance test, the electrodes are characterized with low impedance. After 2000 cycles, the boron-nitrogen doped double-layer capacitors maintain a capacitance retention ratio of above 95%. Its power density can still achieve 220W/kg when the energy density keeps at 3.46Wh/kg. In other words, the electrochemical performance functions of the electric double-layer capacitors are enhanced while the CNTs serve as the electrodes.

Flexible pressure sensors based on piezoresistive induction have recently become a research hotspot due to the simple device structure, low energy consumption, easy readout mechanism and excellent performance. For practical applications, flexible pressure sensors with both high sensitivity and low-cost mass production are highly desirable. Herein, this paper presents a high-sensitivity piezoresistive pressure sensor based on a micro-structured elastic electrode, which is low cost and can be mass-produced by a simple method of sandpaper molding. The micro-structure of the electrode surface under external pressure causes a change in the effective contact area and the distance between the electrodes, which exhibits great pressure sensitivity. The test results show that the surface structure is twice as sensitive as the planar structure under low pressure conditions. This is because of the special morphology of silver nanowires (AgNWs), which exhibits the tip of nanostructures on the surface and realizes the quantum tunneling mechanism. The sensor has high sensitivity for transmitting signals in real time and it can also be used to detect various contact actions. The low cost mass production and high sensitivity of flexible pressure sensors pave the way for electronic skin, wearable healthcare monitors and contact inspection applications.

In this report, the porous Fe₃O₄/C nanocomposites were successfully synthesized by using ferrocene as raw material and dilute nitric acid as solvent via extremely convenient and low-cost one-step calcining method. The formation of porous structure resulted from the aggregation and assembly of numerous nanoparticles. The experimental results show that the crystallinities, morphologies and electrochemical performance of samples were affected by the calcining temperature and carbon content. As an anode for lithium-ion batteries (LIBs), the Fe₃O₄/C nanocomposites obtained at calcination temperature of 500^∘C (Fe₃O₄/C-a500) exhibited remarkable initial specific discharge capacity of 1418mAh g${}^{-1}$ and a reversible capacity retention of 721mAhg${}^{-1}$ after 100 cycles at the current density of 100mAg${}^{-1}$. The excellent properties can be attributed to the high theoretical capacity of Fe₃O₄, the high conductivity of carbon and especially the porous structure, which offered more sites for the storage and insertion of Li ions. Even at the current density of 1000mAhg${}^{-1}$, the reversible capacity of Fe₃O₄/C-a500 can be up to 291mAhg${}^{-1}$, indicating the prepared typical nanocomposite presented excellent electrochemical performances and lithium storage capacity, which may be a promising candidate as the anode material for LIBs.

In this work, a highly efficient p-type Cu₃P/$n$-type g-C₃N₄ heterojunction photocatalyst was synthesized in situ. XRD, UV–Vis, N₂ adsorption, TEM, XPS, PL, and EIS are used to characterize the as-prepared catalysts. The results show that Cu₃P nanoparticles are highly dispersed onto the g-C₃N₄ surface, which obviously promotes the separation rate of electrons and holes. The charge transfer between Cu₃P and g-C₃N₄ follows the “Z-scheme” mechanism. The as-prepared Cu₃P/g-C₃N₄ heterojunction photocatalyst displays the ammonium ion production rate of 7.5mgL${}^{-1}$h${}^{-1}$g${}_{\mathrm{\text{cat}}}^{-1}$, which is 28.8 times higher than that of neat g-C₃N₄, as well as good catalytic stability. The possible reaction mechanism is proposed.

In this paper, a novel and facile method to achieve fluorescent nanosized-diamond based nanowire (NW) is reported. One-dimensional (1D) organic NW has received tremendous attention due to its superior chemical functionality and size-, shape-, and material-dependent properties. In addition, nanosized-diamond is comprehensively studied and investigated due to superior tunable fluorescent properties, cost-effectiveness, facile manufacturing and high biocompatibility. Through thermal treatment, sulfur-modified nanosized-diamond was fabricated by mixing oxidized nanosized-diamond and dibenzyl disulfide at 900^∘C. Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and zeta potential were employed to characterize sulfur-modified nanosized-diamond. After that, porous anodic aluminum oxide template-assisted cathodic electrophoretic deposition method was used to achieve sulfur-modified nanosized-diamond NW. Scanning electron microscopy and transmission electron microscopy were applied to present the one-dimensional structure of the NWs. The optical properties of sulfur nanosized-diamond NW were characterized via ultraviolet-visible spectroscopy and photoluminescence spectroscopy. Finally, the as-synthesized sulfur-modified nanosized-diamond NW-based optical sensor was fabricated to detect vitamin B${}_{12}$ with high sensitivity and selectivity.

1D $\alpha$-MoO₃ nanobelts were prepared using ammonium heptamolybdate tetrahydrate [(NH${}_4{)}_6$Mo₇O${}_{24}\cdot 4$H₂O] as raw material by one-step hydrothermal method without template or guide agent at 180^∘C. The layered $\alpha$-MoO₃ nanobelt electrode has favorable electrochemical performance, and displays a fairly high specific capacitance, which can be up to 445F/g at a current density of 0.5A/g.

Herein, we present the one-pot synthesis of carbon quantum dots (CQDs) using glutathione and used for the optical detection of hydrogen peroxide (H₂O₂). Unlike as reported in other literatures, the detection of H₂O₂ is free of using any additional chromogenic agents or metal ions. The CQDs are synthesized using glutathione by one-pot hydrothermal at 180^∘C. The as-prepared CQDs exhibit good fluorescence response toward H₂O₂ without involving extra chromogenic substances. The addition of 300$\mu$M H₂O₂ to CQDs induces the quenching of fluorescence, besides the yellow becomes colorless. The decrease in the fluorescence is attributed to the polymeric structure of CQDs disbanded by H₂O₂. In addition, the practical application of the present method was verified by determining H₂O₂ in human urine samples.

The charge recombination caused by surface defects limits photovoltaic properties of quantum dot-sensitized solar cells (QDSSCs), which can be suppressed by modifying organic or inorganic molecules and atomic ligands. In this paper, octa-aminopropyl polyhedral oligomeric silsesquioxane (OA-POSS) connected and modified near-infrared absorption CdSeTe quantum dots (QDs) through coupling agent (1-ethyl-3-3-dimethylaminopropyl carbodiimide hydrochloride). The results suggest that OA-POSS reduces the surface defects of CdSeTe QDs and suppresses charge recombination. Therefore, the power conversion efficiency improves nearly 41%, which increases from 2.00% to 2.82%.

In this study, a simple one-step hydrothermal method was developed to prepare a novel hierarchical CoNi₂S₄ nanostructure similar to rambutan fruit. The surface microstructural study clearly visualized that the rambutan-like CoNi₂S₄ consists of nanorods grown directly on the surface of spherical core structures. The close attachment of the nanorods to the spheres increased the active areas of the electrode, which facilitates efficient charge transport from the nanorods to the spherical core structure. CoNi₂S₄ with a rambutan-like hierarchical structure showed an excellent specific capacitance of 944Fg${}^{-1}$ at 1Ag${}^{-1}$, considerable rate capacitance (75.6% retention at 10Ag${}^{-1}$) and excellent cycling life (91.1% retention after 5000 circulations) in the three-electrode system. Besides, the assembled hybrid supercapacitor based on CoNi₂S₄ and reduced graphene oxide exhibited a high specific energy density of 23.58Whkg${}^{-1}$ at the power density of 800Wkg${}^{-1}$.

Practical application of oxygen evolution reaction (OER) in energy conversion devices, such as water splitting and metal-air batteries, relies on the development of highly efficient and stable electrocatalysts and is still challengeable. Here, Nickel modulated ternary Iron tungsten nitride (Ni-FeWN${}_2)$ nanosheets are synthesized through a facile hydrothermal growth method and subsequently nitriding process for boosting OER. A potential of 1.57V at the current density of 10mA/cm² and Tafel slope (40mV/dec) are achieved on Ni-FeWN₂, much lower than that on Ni-free FeWN₂ and commercial IrO₂. More importantly, Ni-FeWN₂ nanosheets display high stability and electrocatalytic activity toward driving oxygen evolution efficiently in alkaline media.

CoNi magnetic nanoparticles (NPs) and hybrid architectures have attracted tremendous attention from numerous applications. In this study, a facile approach based on one-step metal-organic chemical vapor deposition (MOCVD) was developed to fabricate CoNi/C core/shell NPs with an extremely small core size of $\sim$3.7nm and an ultrathin shell thickness of 1–3nm. Only 10wt.% CoNi/C core/shell NP-filled composites with thickness of 1.6mm exhibit an optimal reflection loss value of $-$25.7dB and an absorbing bandwidth value up to 6.2GHz. The extremely small core/shell NPs are demonstrated to have enhanced electromagnetic parameters (i.e., complex permittivity and permeability), reflection loss and broadened effective absorption bandwidth, as compared to the relatively larger NPs. The superior microwave absorbing performance should be attributed to the increased specific area with enriched interfacial polarization. The as-synthesized extremely small CoNi/C core/shell NPs are expected to be a fascinating candidate for efficient microwave absorption material with lightweight and thin thickness.

Photoluminescent carbon dots (CDs) are synthesized and derived from carboxyl-modified PAMAM dendrimer precursor by a one-pot solvothermal method. The obtained CDs exhibit highly bright Yellow-emitting fluorescence with quantum yield of 62.6%. In practice, using their excellent photoluminescence and good compatibility, the CDs are processed with polymers for various fluorescent nanocomposites (such as film, microfiber and bulk hydrogel) and applied as light conversion materials for white LEDs.

A simple hydrothermal conversion method for the preparation of Ag₃PO₄/SnO₂ composite photocatalyst has been developed. The morphological properties of the nanocomposites are studied using transmission electron microscopy (TEM), energy dispersive spectrometer (EDS), X-ray powder diffraction (XRD) and other methods. Different properties of catalysts are prepared by adjusting the temperature of hydrothermal reaction and the volume ratio. The prepared photocatalyst is tested by degradation of tetracycline solution under visible light show that the degradation rate of tetracycline can reach 74% when the initial [Ag₃PO₄]/[SnO₂] molar ratio is 15 and the temperature is 140^∘C. Moreover, by constructing Ag₃PO₄/SnO₂ composite structure, the impedance and photocurrent of material are enhanced significantly according to the electrochemical characterization.

A novel titanium dioxide–graphene–polyaniline (TiO₂–RGO–PANI) hybrid was prepared by the one-pot method and used as a nonenzymatic electrochemical sensor for glucose detection. The composition and structural morphology of the as-prepared composites were determined by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The characterization results showed that TiO₂–RGO–PANI is mainly composed of Ti, O, C and N and their weight percentages are 67.68%, 21.57%, 10.70% and 0.05%, respectively, indicating that the TiO₂–RGO–PANI composite catalyst has been successfully prepared and presents a poriferous coral structure. A series of electrochemical tests such as cyclic voltammetry tests declared that TiO₂–RGO–PANI composite possessed a low limit of detection (LOD) (7.46$\mu$M), good repeatability, selectivity and stability. In the concentration range of 10–180$\mu$M, the hybrid presented linear diffusion, and the linear equation was $I_{pa}=0.21338+0.01392$ (C/mM), the correlation coefficient $R^2=0.9912$. In addition, the comparison of the merits of this proposed electrode with some recent nonenzymatic glucose sensors indicates that this highly sensitive TiO₂–RGO–PANI complex glucose sensor provides a simple, low-cost, nonenzymatic method for glucose detection, and has promising applications in clinical diagnostics and medical analysis.