Due to high stability and sensitivity, inorganic nanomaterials with enzyme-like activity have brilliant application prospects. Tuning the enzyme-like activity plays great significance for promoting the development of nanozymes. In this work, Pt-Au dendritic nanoparticles (Pt-Au DNPs) with good uniformity and stability were synthesized by a simple liquid phase reduction method, and used to colorimetrically detect ascorbic acid (AA) by using their oxidase-like activity to catalyze the oxidation of TMB (3,3′,5,5′-tetramethylbenzidine). The oxidase-like activity was found to be highly influenced by the composition and structure of Pt-Au dendritic nanoparticles, and the relationship between kinetic parameters and nanoparticle structure was investigated. Quantitative analysis of ascorbic acid in the 1-15 μmol/L range was performed with good linear relationship, and the detection limit was 78 nmol/L. At the same time, it’s found that continuous reaction would reduce the catalytic performance of Pt-Au DNPs, but still has the potential to be reused, which is not common. Data from this research not only suggests a method for synthesizing Pt-Au DNPs, but also shows its potential for AA analysis in biological samples.

Chemical vapor deposition (CVD) is an effective method for preparing large-size and high-quality graphene materials. The properties of the metal catalysts are direcly related to the quality of the prepared graphene films, so the surface pretreatment of the metal catalysts is required. In this study, the effects of different pretreatment methods on copper substrates are investigated, and the combination of passivation paste pickling and electrochemical polishing is proposed to be an effective method to modify the surface morphology of copper catalyst. The electrochemical polishing parameters (such as voltage, time) and the copper substrate annealing parameters (such as annealing temperature, time) are systematically studied. This study demonstrates that high electrochemical polishing voltage and long polishing time easily lead to the excessive polishing. It is appropriate to set the polishing voltage and polishing time to 8 V and 8 min, respectively. It is found that the annealing temperature and time have significant effects on the grain size of the copper catalyst. After annealing at 1000 ℃ for 30 min, the grain is larger and more uniform. In addition, the structure characterization of graphene prepared by CVD is also performed. According to the SEM image and Raman spectrum, the few-layer, high-quality graphene film is successfully prepared.

BN and BN/SiC interphases were deposited on the surface of SiC fibers by CVI process, and the mechanical properties of the as-received and coated fibers were evaluated. SiCf/SiC minicomposites were prepared by PIP using the as-received, BN-coated and BN/SiC coated fiber bundles as reinforcements. The effects of interphases on the mechanical properties of the composites were studied. The results show that the interphases prepared by CVI process are uniform and compact. The deposited BN interphase contains hexagonal phases with small crystal size (1.76 nm). The deposited SiC interphase has better crystallinity and larger grain size (18.73 nm) than BN interphase. The elastic modulus of coated SiC fibers shows basically no change, but the tensile strength decreases. The maximum tensile load and fracture strain of SiCf/ BN/SiC and SiCf/(BN/SiC)/SiC minicomposites are significantly increased, in comparison to SiCf/SiC minicomposites. It can be seen from the cross-sections of SiCf/BN/SiC and SiCf/(BN/SiC)/SiC mini-composites that the fibers with interphases pull out obviously relative to SiCf/SiC mini-composites, and the BN interphases played a reinforcing role in the tensile fracture process of the composites. The composites with interphases exhibit obvious fiber pull-out resulting in more energy consumption during the fracture, so that the composite can endure more load.

To obtain high performance needled C/C composites, a series of needled non-woven carbon fiber felt with different characteristics was prepared. The needled C/C composites were prepared by means of high-pressure impregnation-carbonization, and their microstructure features, mechanical properties and thermo-physical properties of needled C/C composites were characterized. The investigation results show that the types of preform structure have obvious effects on the mechanical and thermo-physical properties of the C/C composites. When the preform is produced with key characteristics of needling depth at 12 mm, needling density at 22 pin/cm 2 and fiber web/weft less ply at 1.0:4.8, the needle C/C composites shows excellent comprehensive performance, with tensile strength, compression strength, flexural strength, in-plane shear strength, and interlaminar shear strength of 207, 228, 285, 54 and 28 MPa, respectively.

To study the respective growths of micro-arc oxidation (MAO) ceramic coatings under three phase duty cycles of 40%-50%-60%, 50%-60%-40%, and 60%-50%-40%, and to thereby improve the compactness and hydrogen permeation resistance of the MAO ceramic coatings on the surface of zirconium hydride, the zirconium hydride matrix went through MAO treatment under constant voltage in the phosphate electrolyte system. On the one hand, the morphology, phase structure, and thickness of the ceramic coatings were analyzed by using scanning electron microscope (SEM), X-ray diffractometer (XRD), and film thickness meter. On the other hand, the hydrogen permeation resistance of the ceramic coatings under the different phase duty cycle was obtained through a vacuum dehydrogenation experiment. The research results indicate that under three phase duty cycle, the accumulated thickness of zirconium oxide ceramic coatings on the surface of ZrH1.8 are 162.6, 175.9, and 158.7 μm, respectively; all of the produced MAO ceramic coatings consist of three phases, namely M-ZrO2, T-ZrO2, and Zr0.95Ce0.05O2. Phase duty cycle has no significant effect on the phase composition of ceramic coatings. Under the phase duty cycle of 40%-50%-60%, the ceramic coating achieves on the surface of zirconium hydride has the thickness of 162.6 μm and the Permeation Reduction Factor (PRF) value of 12.5, indicating a relatively satisfactory hydrogen permeation resistance.

In this study, the electronic structure and optical properties of graphene oxide in different structures with single point defect are studied under local density of states approximation and generalized gradient approximation by first-principles calculations based on the density functional theory. The results show that four models are mechanically stable, among which the oxide graphene containing unsaturated oxygen atoms shows an important application potential in water cracking and catalysis. The calculated band structures and partial-wave density of states show that the model containing unsaturated oxygen atoms exhibits indirect band gap, while other models exhibit direct band gap, and the doping type and band gap values vary with different models. The absorption spectrum of graphene oxide is anisotropic, and the absorption edge moves to the near-UV and visible region in the direction perpendicular to the plane. The optical absorption coefficient containing sp 3 hybrid is slightly higher than that containing sp 2 hybrid, suggesting that the carbon-oxygen double bond and hanging bond have important influence on the absorption spectrum.

A series of tunable-luminescence MOF/CA, MOF/CA+RhB, MOF/CA+CV and MOF/CA+RhB+CV composite light-emitting materials were prepared by combining calcein (CA), rhodamine B (RhB), crystal violet (CV) with MOF using Cd as metal ion, isophthalic acid and benzimidazole as ligand by the one-step method at room temperature. The influence of the initial addition amount and ratio of dyes on the fluorescence properties of MOF/Dye composites was discussed. With the increase of CA amount, the characteristic fluorescence emission intensity of CA increased firstly and then decreased accompanied with red-shift. Although the position of the characteristic fluorescence emission wavelength of RhB or CV remained unchanged due to the unchanged addition amount, the characteristic fluorescence emission intensity of CA changed like CA. MOF/CA3+RhB+CV composite with white light emission was further prepared by adjusting the molar ratio of dyes using MOF as a platform. Its chromaticity coordinate (0.335, 0.321) was close to the ideal white light coordinate (0.333, 0.333).

Histidine-functionalized carbon dot/graphene aerogel (His-CDs/GA) were synthesized via the one-step hydrothermal method. The as-prepared His-CDs/GA exhibits unique three-dimensional porous structure, rich nitrogen and oxygen-containing functional groups, which facilitate the rapid diffusion of electrolyte ions and provide more active sites. When the mass ratio of GO and His-CDs is 2 : 1, the specific capacitance of His-CDs/GA-2 reaches 304 F·g -1 at a current density of 1 A·g -1, which increases 76.7% compared with that of GA (172 F·g-1). With the current density increasing from 1 A·g -1 to 50 A·g -1, the specific capacitance retention of His-CDs/GA-2 achieves 71.4%. The specific capacitance of His-CDs/GA-2 still remains 93.5% over 30000 cycles at 10 A·g -1. In addition, a symmetrical supercapacitor assembled by His-CDs/GA possesses a high energy density of 10.14 Wh/kg at a power density of 250 W/kg, and good cyclic performance with 88.4% capacitance retention at 5 A·g -1 over 20000 cycles. The results show that His-CDs/GA is a promising electrode material for supercapacitors.

In order to improve the electrochemical performance, the phosphate ion doped MnFe2O4 (PMFO) was synthesized by a hydrothermal method combined with a subsequent phosphatization treatment. Both the specific surface area and electrical conductivity of electrode material are improved by the phosphate ion functionalization. Furthermore, the specific capacitance is 750 F/g at 1 A/g for PMFO, which is almost 1.7% higher than that of MFO. Besides, the cyclic stability of PMFO electrode is also improved. The asymmetric supercapacitors (ASCs) assembled by positive electrode PMFO and actived negative electrode carbon (AC) display an ultrahigh energy density of 168.8 Wh/kg at a power density of 2.7 kW/kg. The PMFO is demonstrated as a promising electrode material for supercapacitor applications.

Ni-Co-S/CA composite aerogels were prepared by hydrothermal method using bacterial cellulose-derived carbon aerogels (CA) as support. The microstructure and properties of the composites were adjusted via adding trace vanadium. The characterization results show that the main phase of Ni-Co-S is NiCo2S4 with the secondary phase of NiS2. With the increment of the nickel-cobalt salt concentration, the load amount increases, and the peak current density of electrocatalysis firstly upgraded and then degraded. After being doped with a small amount of vanadium at lower nickel-cobalt salt concentration, Ni-Co-S transforms from spherical particles with high crystallinity to square particles with low crystallinity, and its electrocatalytic activity and stability are improved. Under the preparative conditions of 0.01 mol/L total concentration of nickel-cobalt salt and 3mol% vanadium salt, the as-obtained electrode exhibits the optimal catalytic performance for methanol oxidation. Compared with the sample without V doping, its peak current density (78.1 mA/cm 2) enhanced by 45.7% at least. The Ni-Co-S/CA composite aerogel electrodes with the advantages of light weight and high porosity, is expected to be applied in portable direct methanol fuel cell.

Herein, we report a kind of NiCu-based composite phosphides electrocatalyst(NiCuP/NM), which was prepared in situ on nickel mesh substrate by one-step hydrothermal method with NaH2PO2, CuSO4, NiSO4 as initial materials. The morphology, crystal structure, composition, and electrocatalytic performance of NiCuP/NM were characterized. Under the optimal preparation conditions of Ni, Cu and P(molar ratio 8 : 1 : 20), hydrothermal synthesis at 140 ℃ for 24 h, the obtained composite electrocatalyst displayed three-level micro-nanostructure with Ni2P and Cu3P as main crystal phases. At the current density of 10 mA·cm -2, the required HER (Hydrogen Evolution Reaction) overpotential and HzOR (Hydrazine Oxidation Reaction) potential of NiCuP/NM were 165 and 49 mV, respectively. In the two-electrode system, the decomposition tank pressure for the NiCuP/NM cell at the same current density was only 0.750 V which remained substantially unchanged for 24 h catalysis, exhibiting excellent catalytic stability. NiCuP/NM displays prominent electrocatalytic performances towards HER or HzOR in both three-electrode and two-electrode systems, which can be ascribed to two aspects. On the one hand, the 14-fold electrochemical active surface area compared with original nickel mesh enables NiCuP/NM expose huge number of catalytic active sites in both HER and HzOR. On the other hand, the electronic structure modification of Ni and Cu atoms induced by doping P atom brings great improvement of intrinsic HzOR activity of electrode materials. This study provides a new perspective for nanoscale synthesis and promotes the development of novel nanopores in fuel cell and energy conversion applications.

Electrocatalytic hydrodechlorination technology possesses great potential in the field of chlorinated organic compound treatment due to the high efficiency, environmental friendliness, etc. The amorphous Pd-P/polypyrrole(PPy)/foam Ni electrode was prepared by electrochemical deposition for electrochemical hydrodechlorination of the pentachlorophenol (PCP). Morphology and chemical structure of Pd-P on the PPy/foam Ni electrode was investigated by the Scanning Electron Microscope (SEM), Transmission Electron Microscope (TEM), X-ray diffraction analysis (XRD), and X-ray photoelectron spectroscope (XPS). The result indicated that the Pd-P catalyst was evenly dispersed on the PPy/foam Ni electrode with small particles and changed from crystalline state to amorphous state. The electrocatalytic reduction of PCP certificated that the doping of P significantly increased the catalytic activity of the electrode. The degradation efficiency of PCP reached 90.8% after electrocatalytic reduction for 180 min under the condition of n(Pd)/n(P)=1 : 3, Pd loading=0.15 mg/cm 2, CH2SO4=0.20 mol/L and Vcathode=-1.2 V. In addition, the Pd-P/PPy/foam Ni electrode exhibited high electrocatalytic stability after reused for 8 times without any notable deactivation.

Porous microsphere cell microcarrier with macroporous structure can not only amplify cells in vitro, but also serve as cell delivery tools to deliver cells to damaged tissues by injection. Bioglass (BG) is an inorganic material with excellent biological activity, however, it is difficult to directly prepare microcarriers with macroporous structure. Therefore, in this study, a BG/poly-lactic acid (PLA) porous microspheres was prepared by double emulsion method. The morphology and structure of the microsphere were characterized by SEM, and the load of BG in the microsphere was characterized by thermo gravimetric analysis and its ion release was detected by ICP. Cell proliferation experiments showed that cells could adhere and grow on the surface and inside of the microspheres. The results show that the microsphere with interconnected open-pore microstructure is suit for cell adhesion and proliferation. Bioglass can promote cell proliferation in the microspheres and the obtained BG/PLA composite microsphere has great potential applications in tissue engineering.

During charge and discharge of lithium-ion battery, the concentration gradient produced by lithium- ion diffusion process and deformation caused by lithiation expansion of the active material result in diffusion-induced stress. Excessive diffusion-induced stress can cause various mechanical failure modes such as cracking of active particles, separation between active particles, fracture of active layers, and delamination between active layers and current collectors, which eventually leads to a series of failure phenomena such as capacity attenuation, impedance rise and cycle life loss of the battery. Therefore, the diffusion-induced stress and the derived failure mechanism of lithium-ion battery become one of the research hotspots in the field of lithium-ion batteries, which has important theoretical and practical value. In this paper, research progress of the failure mechanism of lithium-ion battery caused by diffusion-induced stress in recent years is reviewed from different levels of the active particle, the active electrode, the half-cell, the cell unit, and the cell. The generation mechanism and research methods of diffusion-induced stress are introduced. The influence of diffusion-induced stress on the mechanical and electrochemical properties of the battery is analyzed, and the influencing factors of the diffusion-induced stress are summarized. Finally, the future research directions and development trends are prospected.

All inorganic perovskite nanocrystals with narrow-emission, high quantum efficiency and high carrier mobility have been widely applied in the fields of light emitting diodes and solar cells. However, present surface ligands of the perovskite nanocrystals are in a dynamic bonding state, which easily fall off during separation and purification processes, resulting in the deterioration of quantum efficiency and stability. Besides, the ionic characteristic of halide perovskites makes it extremely sensitive to polar solvents. These disadvantages severely restrict the practical application of perovskite nanocrystals in optoelectronic devices. In this review, based on the surface state of perovskite nanocrystals, the effects of passivation strategies with Lewis acid, Lewis base and surface coating on optical properties, and stability of CsPbX3 perovskite nanocrystals are analyzed in detail combined with the domestic and abroad research work. Further optimization and improvement of the stability of CsPbX3 are prospected.