Bionic titania coating carbon multi-layer material derived from natural leaf and its superior photocatalytic performance

Bionic titania coating carbon multi-layer material was fabricated by employing canna leaves as substrate and carbon precursor. Titania nanocrystals were assembled and coated on the natural films. The carbonation treatment under pure N_2 atmosphere yielded the ultrathin multi-film hybrid material. The carbon layer was coated with small anatase titania crystallite(8–10 nm) and possessed a highly specific surface area of 248.3 m~2 g~(-1). Examination using UV–visible spectrophotometer(UV–vis) showed that the band gap of the multi-layer material was reduced to 2.75 eV, and the hydrogen production by photocatalytic splitting of water under visible light irradiation was about 302 μmol g~(-1) after six hour.     

Oxygen-rich carbon-nitrogen quantum dots as cocatalysts for enhanced photocatalytic H2 production activity of TiO2 nanofibers

We developed an one-step hydrothermal method to synthesize carbon-nitrogen quantum dots(CNQDs) with oxygen-rich functional groups.The sample was characterized by TEM,AFM,FT-IR,XPS,UV-vis absorption and PL spectra.The 0/C and N/C atomic ratio of typical CNQDs with diameters of 3-6 nm are ca.0.4 and 0.2,respectively.Without noble metal cocatalyst,the photocatalytic H_2 production rate of CNQDs/TiO_2 nanofibers(NFs)(112.4 μmol h~(-1) g~(-1)) is 1.8 times higher than that of TiO_2 NFs.The good absorption of light contributes to the enhanced photocatalytic H_2 performance.The CNQDs could be promising in biomedical imaging,optical data recording storage and photo/electrocatalysis,etc.     

Fabrication of fine spongy nanoporous Ag-Au alloys with improved catalysis properties

Fine NP-AgAu(nanoporous AgAu) alloys with spongy structure was fabricated by chemical dealloying from rapidly solidified amorphous precursors Ag_(38.75-x)Cu_(38.75)Si_(22.5)Au_x(x=0, 0.5, 1 and 5). The results indicate that the addition of small content Au in precursor can refine both the ligaments and pores obviously. Among the present components of the precursors, NP-AgAu alloys dealloying from Ag_(37.75)Cu_(38.75)Si_(22.5)Au_1 had the finest spongy structure. The size of pores was 5–10 nm and the grain size of ligaments was 10–20 nm. It also had the highest surface area of 106.83 m~2g~(-1) and the best catalytic activity towards electro-oxidation of formaldehyde with the peak current of 665 mA mg~(-1).     

Electroch emical properties and interfacial reactions of LiNi0.5Mn1.5O4-δ nanorods

LiNi0.5Mn1.5O4-δ which possesses a high voltage of 4.7 V vs.Li+/Li and stable structure has been considered as a promising cathode material for high energy Li-ion batteries.In this study,well-crystalli...     

A single-step synthesis of nitrogen-doped graphene sheets decorated with cobalt hydroxide nanoflakes for the determination of dopamine

Nitrogen-doped reduced graphene oxide(NrGO)sheets decorated with Co(OH)_2nanoflakes were prepared by a single-step hydrothermal process.The morphological and structural characterizations of as synthesized Nr GO@Co(OH)_2nanoflakes were performed by field emission scanning electron microscopy(FESEM),EDX-mapping and X-ray diffraction(XRD).Nr GO@Co(OH)_2nanoflakes modified glassy carbon electrode(GCE)was used for electrochemical sensing of dopamine in neutral medium.The nanocomposite modified electrode showed enhanced electrochemical sensing ability for the detection of dopamine and the limit of detection(Lo D)was found to be 0.201μM with a sensitivity value of 0.0286±0.002 m A m M~(-1).Interference studies revealed that Nr GO@Co(OH)_2─GCE endow excellent selectivity for DA detection even in the presence of higher concentration of common co-existing physiological interfering analytes.Additionally,proposed sensor demonstrated excellent performance in urine samples with promising reproducibility and stability.     

Dissolution behavior of bioactive glass ceramics with different CaO/MgO ratios in SBF-K9 and r-SBF

In the present work,we studied dissolution behavior of three glass ceramics samples each having 34 SiO2–14.5 P2O5–1 CaF2–0.5 MgF2(%wt)and ratio of CaO/MgO varying from 11.5:1 to 1:11.5 in conventional SBF(SBF-K9) and revised SBF(r-SBF) that has ionic concentration exactly equal to that of human blood plasma.For that purpose,samples were immersed in fluids for different time periods upto 25 days.Thin film XRD analysis revealed the diffusive nature of the phases on the surfaces of samples after soaking for different time periods in r-SBF.It showed the poor precipitation and small thickness of the HCAp layer on the samples as compared to that in SBF-K9,thus indicating the fitness and sensitivity of r-SBF for in-vitro characterization of samples.AAS,FTIR and EDS revealed slow bonding rate on the surfaces of the samples in r-SBF than that in SBF-K9 that showed the dependence of bond formation on the composition of the materials as well as on the physiological fluid used for in-vitro characterization.The rate of HCAp formation was slower in r-SBF due to more competitive adsorption of CO3 ions to Ca and Mg ions owing to greater amount of CO3 in r-SBF than that in SBF-K9.It shows the importance of CO3 content in the physiological fluids for the in-vitro assessment of samples.So,r-SBF is recommended to be used for assessment of samples to clearly understand their behavior in-vivo.     

Structure and properties of solid-state synthesiz ed poly (3,4-propylenedi oxythiophene) /nano-ZnO composite

Poly（3,4-propylenedioxythiophene）/nano-Zinic Oxide（PProDOT/ZnO） composites with the content of 3-7 wt%nano-ZnO were synthesized by the solid-state method with FeCl₃ as oxidant.The structure and morphology of the composites were characterized by Fourier transform infrared（FTIR）spectroscopy,ultraviolet-visible（UV-vis） absorption spectroscopy,X-ray diffraction（XRD） and transmission electron microscopy（TEM）.The electrochemical performances of the composites were investigated by galvanostatic charge-discharge,cyclic voltammetry and electrochemical impedance spectroscopy（EIS）.The photocatalytic activities of the composites were investigated by the degradation of methylene blue（MB） dyes in aqueous medium under UV light irradiation.The results from FTIR and UV-vis spectra showed that the PProDOT/ZnO composites were successfully synthesized by solid-state method,and nano-ZnO had great influences on the conjugation length and oxidation degree of the polymers.Furthermore,the PProDOT/5 wt%ZnO had the highest conjugation and oxidation degree among the composites.The results of XRD analysis indicated that there were some FeCl₄^- ions as doping agent in the PProDOT matrix,and the content of ZnO had no effect on diffraction pattern of PProDOT.Morphological studies revealed that the pure PProDOT and composites had similar morphological structure,and all the composites displayed an irregular sponge like morphology.The results of electrochemical tests showed that the PProDOT/5 wt%ZnO had a higher electrochemical activity with a specific capacitance value of 220 F g^-1 than others.The results from photocatalytic activities of the composites indicated that the PProDOT/5 wt%ZnO had better photocatalytic activity than other composites.     

Properties of garnet-type Li6La3ZrTaO12 solid electrolyte films fabricated by aerosol deposition method

The garnet-type Li_6La_3ZrTaO_(12)(LLZT) solid electrolyte films were fabricated by aerosol deposition(AD)method.Ball-milled LLZT powder with a cubic garnet structure and a particle size of 1-2 urn was used as raw material and deposited directly on a SUS316L or a glass substrate via impact consolidation.As-deposited LLZT film has a cubic garnet structure but contains Li_2CO_3 and La_2Zr_2O_7 phases.SEM observation revealed that the film consists of LLZT particles fractured into submicron size.The impurity phase formation during AD process was caused by the local heating by the collision between LLZT particles and deposition surface and reaction with CO_2.The Li~+ ion conductivity of LLZT film was estimated to be 0.24 × 10~(-5)S cm~(-1) at room temperature.Electronic conductivity of LLZT film was confirmed to be around 10~(-12) S cm~(-1),indicating the dominant Li~+ ion conduction of LLZT film.     

Bilirubin sensor based on CuO-CdO composites deposited in a nafion/glassy carbon electrode matrixes

Copper oxide-cadmium oxide nanocomposites(CuO-CdO NCs) were synthesized by solvothermal technique in a basic medium. CuO-CdO NCs were characterized using conventional techniques, such as Fourier Transform Infrared Spectroscopy(FTIR), UV–Visible Spectroscopy(UV/Vis), Field-Emission Scanning Electron Microscopy(FESEM), X-ray electron dispersive spectroscopy(XEDS), X-ray photoelectron spectroscopy(XPS), and powder X-ray diffraction(XRD). A selective and enzyme-less Bilirubin(BLR) sensor was developed with a thin-layer of NCs onto a glassy carbon electrode(GCE, surface area = 0.0316 cm~2) using 5% nafion binders at room conditions. Improved electrochemical performances of higher sensitivity, lower detection limit,linear dynamic range(LDR), and long-term stability of preferred BLR were achieved by a reliable currentvoltage(I-V) approach. The calibration curve was found linear(R~2= 0.9347) in a wide range of BLR concentration(10.0 pM ~ 10.0 mM). Based on the signal to noise ratio value of 3, the sensitivity and limit of detection(LOD) of the sensor were calculated as 95.0 pA μM~(-1) cm~(-2) and 1.0 ± 0.1 pM respectively.Solvothermally synthesized CuO-CdO NCs/GCE is an excellent advancement of developing a selective and sensitive BLR sensor by electrochemical approach and practically implemented in real sample applications.     

Microstructure, mechanical and thermo-physical properties of hot-pressed Al2O3-GdAlO3-ZrO2 ceramics with eutectic composition

A low cost chemical co-precipitation method was employed to fabricate nanoscale Al_2O_3-GdAlO_3-ZrO_2 powder with eutectic composition. A careful control of reaction conditions was required during the preparation. The synthesized nanopowders exhibited a particle size of 20-200 nm, and were highly dispersive and uniform. The results showed that calcination temperature had an important influence on the phase constituents of the nanopowders. With increasing the calcination temperature, a phase transformation from θ-Al_2O_3 to α-Al_2O_3 and a thermal decomposition from Gd_3 Al_5O_(12)(GdAG) to GdAlO_3 and α-Al_2O_3 occurred in sequence. A calcination temperature of 1300 ℃ was needed for the crystallization of α-Al_2 O_3. These nanosized powders were consolidated via hot pressing to produce a fully densified ceramic composite with eutectic composition. The Al_2O_3-GdAlO_3-ZrO_2 ceramic hot-pressed at 1500 ℃ exhibited a relative density of 99.4%, a flexural strength of 485 MPa and a fracture toughness of 6.5 MPa m~(1/2). The ceramic had a thermal conductivity of 1.9 W m K~(-1) at 1200 ℃ and a thermal expansion coefficient of 9.49 ×10~(-6) K~(-1) at 1100 ℃.     

Electrochemical properties of LaFeO3-rGO composite

LaFeO_3-xwt% r GO composite(x = 8, 10, 12) was synthesized by ultraphonic stirring and lyophilization method.SEM, TEM and XRD results show that the perovskite-type LaFeO_3 was dispersed by rGO to form special porous structure due to the gauze-shaped wrinkles and folds structure of rGO. It was found that the special porous structure can effectively increase the specific surface area and suppress particle aggregation of LaFeO_3, thus improving the electrical conductivity and appreciably enhancing the electrochemical properties of LaFeO_3. As compared with LaFeO_3, the maximum discharge capacity of the composite(x=10) increased from 209.5 mAhg~(–1) to 334.6 mAhg~(–1).The High rate dischargeability at a discharge current density of 1500 mAg~(–1)(HRD1500) and the capacity retention rate after 100 charge/discharge cycles(S100) of the composite increased by 9% and 17%, respectively.     

Mechanical and thermal properties of NpO2 using LSDAt U approach

The elastic constants,bulk modulus,shear modulus,Young’s modulus,Debye temperature,isobaric heat capacity and minimum thermal conductivity are estimated for NpO2 using plane-wave pseudopotential method within the local spin density approximation plus Hubbard U(LSDAtU) theory.The computed lattice constants are in good agreement with the available experimental results and then three independent elastic constants were computed by means of the stress–strain method.From the knowledge of the elastic constants,the values of Young’s modulus,Poisson,Debye temperature and minimum thermal conductivity are obtained and they are 218 GPa,0.288,453.5 K and0.99 Wm-1K-1,respectively.The obtained mechanical and thermal properties of NpO2 are in agreement with the previous experimental and theoretical data.Our investigations which are unobtainable from previous report can provide valuable reference in the future.     

La2O3–Al2O3 –SiO2 glass-infiltrated 3Y-TZP all-ceramic composite for the dental restora tive application

The 3 mol% yttria stabilized tetragonal zirconia polycrystals (3Y-TZP) powder had three particle size distributions, while the fine one was lower than 100 nm. The 3Y-TZP compact was prepared by dry-pressing under pressures ranged from 10 to 30 MPa and then presintered at 1250°C for 2 h. The matrix dry-pressed under the pressure of 20 MPa had a porosity of 16.7% and could be easily processed by computer aided design and computer aided manufacturing (CAD/CAM), and which had been infiltrated by the La2O3–Al2O3–SiO2 glass at 1200°C for 4 h. The flexural strength and fracture toughness of the composite were 710.7 MPa and 6.51 MPa m^1/2, respectively. The low shrinkage (0.3%) of the composite can satisfy the net-shape fabrication standard. XRD results illustrated that zirconia in the La2O3–Al2O3–SiO2 glass-infiltrated 3Y-TZP all-ceramic composite was mainly in the tetragonal phase. SEM and EDS results indicated that the pores of the matrix were almost filled by the La2O3–Al2O3 –SiO2 glass     

Hot deformation behavior andfl ow stress modeling of annealed AZ61 Mg alloys

In this study, the hyperbolic-sine type constitutive equation was used to model the flow stress of annealed AZ61 magnesium(Mg) alloys. Hot compression tests were conducted at the temperatures ranging from 250 1C to 450 1C and at the strain rates ranging from 1 10–3s 1to 1 s 1on a Gleeble-3500 thermo-simulation machine. Constitutive equations as a function of strain were established through a simple extension of the hyperbolic sine constitutive relation. The effects of annealing heat treatments on the variations in constitutive parameters with strain were discussed. The hot compressive flow curves exhibited typical features of dynamic recrystallization. Multiple peak flow curves were observed in the annealed specimens upon testing at a strain rate of 1 10 1s–1and at various temperatures. Variations in constitutive parameters with strain were related to flow behavior and dependent on the initial conditions of the test specimens. The flow stresses of annealed AZ61 Mg alloys were predicted well by the strain-dependent constitutive equations of the hyperbolic sine function under the deformation conditions employed in this study.     

Phase stability and thermal conductivity of ytterbia and yttria co-doped zirconia

Rare earth oxides doping has been extensively investigated as one of the effective methods to lower thermal conductivity of 4.55 mol% Y2O3stabilized ZrO2(YSZ) thermal barrier coatings(TBCs).In the present work,5–6 mol% Yb2O3and Y2O3co-doped ZrO2ceramics were synthesized by solid reaction sintering at 1600 1C.The phase stability of the samples after heat treatment at 1500 1C was investigated.Yb2O3and Y2O3co-doped zirconia,especially when Yb2O3/Y2O3≥1,contained less monoclinic phase than single Yb2O3or Y2O3phase doped zirconia,indicating that co-doped zirconia was more stable at high temperature than YSZ.The thermal conductivity of the 3 mol% Yb2O3+3 mol% Y2O3co-doped ZrO2was 1.8 W m 1K 1at 1000 1C,which was more than 20% lower than that of YSZ.     

Effect of pickling processes on the microstructure and properties of electroless Ni–P coating on Mg–7.5Li–2Zn–1Y alloy

The electroless plating Ni–P is prepared on the surface of Mg–7.5Li–2Zn–1Y alloys with different pickling processes.The microstructure and properties of Ni–P coating are investigated.The results show that the Ni–P coatings deposited using the different pickling processes have a different high phosphorus content amorphous Ni–P solid solution structure,and the Ni–P coatings exhibit higher hardness.There is higher phosphorus content of Ni–P amorphous coating using 125 g/L Cr O3and 110 ml/L HNO3(w68%)than using 180 g/L Cr O3and 1 g/L KF during pre-treatment,and the coating structure is more compact,and the Ni–P coatings exhibit more excellent adhesion with substrate(Fcup to22 N).The corrosion potential of Ni–P coating is improved and exhibits good corrosion resistance.As a result,Mg-7.5Li-2Zn-1Y alloy is remarkably protected by the Ni–P coating.     

A facile and green preparation of durian shell-derived carbon electrodes for electrochemical double-layer capacitors

A facile and green preparation of high surface area activated carbons with mixed microporosity and mesoporosity from durian shell waste is reported in this work. The pore structure and surface chemistry of the parent carbon were modified by the combination of ultrasonication and microwave irradiation techniques. The effects of temperature and time in the ultrasonication treatment and power output and time in the microwave irradiation were studied. The electrochemical performance of carbon electrodes for supercapacitors was tested by cyclic voltammeter (CV) and galvanostatic charge–discharge. The results show that the capacitive energy storage of electrodes is critically dependent on the microporosity and surface chemistry of activated carbons. The highest electrode capacitance in this work was 103.6 F/g that prepared from activated carbon modified at an ultrasonication temperature of 323.15 K for 10 min and microwave power output of 900 W for 10 min.     

High-energy ion treatments of amorphous As40Se60 thin films for optical applic ations

The treatment of 100 MeV Ag swift-heavy ion(SHI) irradiation with five different fluences(3 1010, 1 1011, 3 1011, 1 1012, and3 1012ions/cm2) was used to design optical and structural properties of amorphous(a-) As40Se60 chalcogenide thin films. Swanepoel method was applied on transmission measurements to determine the changes in optical bandgap, Tauc parameter and linear optical parameters, i.e., linear optical absorption, extinction coefficient and linear refractive index. Dispersion of the material was determined by Wemple–DiDomenico relation.Changes in nonlinear optical parameters of third-order optical susceptibility and nonlinear refractive index were determined using semi-empirical relations. Changes in surface morphology of the films were investigated using SEM observation, which indicated that fluence 3 1012ions/cm2was upper threshold limit for these films for ion treatment. It is observed that optical bandgap reduces from 1.76 eV to 1.64 eV, and nonlinear refractive index increases from 1.31 10 10[esu] to 1.74 10 10[esu]. Linear refractive index initially increases from 2.80 to 3.52(for fluence3 1010ions/cm2) and then keeps decreasing. The observed changes in optical properties upon irradiation were explained in terms of structural rearrangements by Raman measurement. The study was compiled with the previous literature to propose SHI as an effective optical engineering technique to achieve desired changes according to the need of optical/photonic applications.     

Size-manipulat ion, compacti on and electrical properties of barium manganite nanorods synthesized via the CHM method

A composite-hydroxide mediated method was employed to synthesize barium manganite nanorods.Diameter,surface smoothness and uniformity of these nanorods were optimized by varying reaction temperature and reaction time.The rods with an average diameter of 200 nm and length of1–1.5 μm were obtained at optimum conditions of 200 1C/48 h.The dielectric study of these rods reveals that they have higher value of dielectric constant at lower frequencies which was attributed to the interfacial and rotational type polarizations.Similarly,the increase in dielectric constant with temperature was attributed to the thermal activation of such polarizations.Furthermore,the analysis of ln(J) vs.E1/2characteristics in the temperature range of 300–400 K shows that possible operative conduction mechanism was of Poole–Frenkel type.The value of βexp was found to be 4.85 times greater than the expected theoretical value of feld lowering coeffcient with an internal feld enhancement factor ofα2 23.5.This high value of βexp may be due to some localized electric felds existing inside the sample.     

Bimetallic-organic coordination polymers to prepare N-doped hierarchical porous carbon for high performance supercapacitors

Single metal-organic coordination polymers have limited functions as precursors for porous carbon electrode materials.The construction of bimetallic organic coordination polymers can effectively utilize the advantages of each single metal-organic coordination polymer to improve the performance of the derived carbon materials.Herein,High performance nitrogen-doped porous carbon(BC_(Fe–Ni))have been produced by directly carbonizing bimetallic organic coordination polymers formed by 4,4'-bipyridine(BPD)reaction with Fe Cl_3and NiCl_2.The BC_(Fe–Ni) exhibits high nitrogen content(12.66 at%),large specific surface area(1049.51 m~2g~(-1))and hierarchical porous structure,which contributes to an excellent gravimetric specific gravity of 320.5 Fg~(-1)and 108%of specific capacitance retention after 10000 cycles.The BC_(Fe–Ni)assembled symmetrical supercapacitor shows an energy density of 18.3 Wh kg~(-1)at a power density of 350 W kg~(-1).It is expected that the as-prepared N-doped porous carbon derived from bimetallic-organic coordination polymer is a promising electrode material for high performance energy storage devices.