Search

The cellulose microfibril-precipitated calcium carbonate (CMF–PCC) composite filler has been studied in improving the printing and optical properties of ordinary paper. However, the effect of CMF–PCC composite filler on the properties of Xuan paper, especially the ink diffusion properties, has rarely been investigated. In this study, the CMF–PCC composite filler was prepared by double-exchange reaction. The effects of CMF–PCC composite filler on the physical properties and ink diffusion properties of Xuan paper were detailedly studied. The results showed that the PCC particles in the CMF–PCC composite filler were rhombohedral calcite, with a uniform particle size and high adhesion rate, under the optimum reaction conditions. The Xuan paper filled with the CMF–PCC composite filler had higher tensile strengths and opacity than the conventional PCC or GCC loading. Notably, the CMF–PCC composite filler can effectively improve and regulate the Chinese ink diffusion properties of Xuan paper.

Carbon-based materials have always been a hot issue of research as important electrode materials for supercapacitors. Their capacitance characteristics depend on specific surface area, pore size distribution, and chemical composition etc. In this report, we utilize sodium citrate as a carbon source and melamine and urea as nitrogen sources. We prepared two types of nitrogen-doped hierarchical porous carbons using a simple and environmentally friendly method for supercapacitors in an aqueous solution containing 6 mol/L KOH. The results show, when melamine was used as a nitrogen source, benefit from a larger BET surface area of 819.5463 m2/g, and higher nitrogen content 4.14% show a higher specific capacitance characteristics 383F g−1 at 0.3A g−1 and high capacity retention of 99.6% after 10,000 cycles compared with the product of urea as a nitrogen source.

Reduced graphene oxide (GO) and carboxymethyl cellulose sodium (CMC) composite film was prepared by a simple solution blending method. The obtained composite film was used to modify glassy carbon electrode (GCE) to detect Vitamin B6 (VB6) with electrochemical measurements. Morphologies and stucture of the composite were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR) and electron paramagnetic resonance (EPR). The electrochemistry performances of the GCE modified by GO/CMC composite were investigated by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). The results revealed that CMC and GO were able to form a homogeneous mixture, and the modified GCE presented extremely strong sensitivity towards VB6 such as high detection sensitivity, low detection limit, small Ret value, certain stability and excellent reversibility. The good performance might be attributed to high electrical conductivity and large surface-to-volume ratio of GO which could accelerate electron transfer between the surface of GCE and VB6. The test results showed that GO/CMC composite was a novel electrochemical biosensor for the detection of VB6.

The counter electrode (CE) prominence in dye-sensitized solar cells (DSSCs) is undisputed with research geared towards replacement of Pt with viable substitutes with exceptional conductivity and catalytic activity. Herein, we report the replaceable CE with better performance than that of Pt-based electrode. The chemistry between the graphene oxide and ice templates leads to cellular formation of reduced graphene oxide that achieves greater conductivity to the CE. The simultaneous growth of active edge-oriented MoS2 on the CE through CVD possesses high reflectivity. High reflective MoS2 trends to increase the electroactivity by absorbing more photons from the source to dye molecules. Thus, the synergistic effect of two materials was found to showcase better photovoltaic performance of 7.6% against 7.3% for traditional platinum CE.

Nitrogen-doped graphene quantum dots (N-GQDs) were synthesized by direct electrolysis of a carbon cloth electrode coated with nitrogen-doped nanomesh graphene (NG) in high yield (~ 25%). The N-GQDs emit intense blue fluorescence with a quantum yield (QY) of 10% ± 3%. Meanwhile, the N-GQDs are rich in hydroxyl, carboxyl, basic pyridinic nitrogen, and nitro groups, which are conducive to strengthen the interaction between N-GQDs and Fe3+ for highly sensitive determination of Fe3+ ions. Specifically, the determination for Fe3+ was conducted at different concentrations of N-GQD solution with a wide linear range of 10–1000 μM (150 μg·mL−1) and a low detection limit of 0.19 μM (10 μg·mL−1). Moreover, the fluorescence quenching mechanism illustrated that the functional groups generated by electrochemical oxidation enhanced the interaction of N-GQDs and Fe3+, and the narrow band gap (2.83 eV) of N-GQDs accomplished electron transfer from N-GQDs to Fe3+ easily.

Direct evidence of effects of surface plasmon resonance(SPR) of gold nanorods(GNRs) on dual-band light absorption enhancement with coupling dye molecules was reported by introducing gold nanorod@SiO2(GNR@SiO2) core-shell nanoparticles into a photoelectric conversion system. GNR with asymmetric shape had unusual anisotropic SPR[transversal surface plasmon resonance(TSPR) and longitudinal surface plasmon resonance(LSPR)]. The excel-lent SPR of GNR made it a promising candidate as enhancing light absorption material to increase power conversion efficiency(PCE). The PCE was improved nearly 17.2% upon incorporating GNRs, mostly due to the increase in Jsc, while Voc and FF were unchanged. The improvement was mostly contributed by the SPR of the GNRs with coupling of N719. And there was also a complementary to N719 in visible light range. Therefore, SPR is an effective tool in improving the photocurrent and consequently enhancement of PCE. The TSPR and LSPR effects of GNRs on light harvesting were reflected in the increased monochromatic incident photon-to-electron conversion efficiency(IPCE). We also utilized finite-difference time-domain(FDTD) to investigate the light coupling of GNRs with TiO2. Compare to the base anode, the IPCE of optimized electrode showed significant improvement and peaks broadening at 500–600 nm and 610–710 nm. We got an increase in overall conversion efficiency from 6.4% to 7.5%.

Nitrogen-oxygen co-doped corrugation-like porous carbon (NO-PC) has been developed by direct pyrolysis of formaldehyde-melamine polymer containing manganese nitrate. The melamine, formaldehyde and manganese nitrate act as nitrogen, oxygen source and pore-foaming agent, respectively. NO-PC exhibits favorable porous architecture for efficient ion transfer and moderate heteroatom doping for additional pseudocapacitance, which synergistically enhances the electrochemical performance of the NO-PC-based supercapacitor. The electrode delivers specific capacitance of 240 F/g at 0.3 A/g when tested in 6 mol/L KOH electrolyte, good rate capability (capacitance retention of 83.3% at 5 A/g) as well as stable cycling performance (capacitance remains ~96% after 10000 cycles at 3 A/g). The facile synthesis with unique architecture and chemistry modification offers a promising candidate for electrode material of energy storage devices.

Though the transition-metal dichalcogenides (TMDs) were proven to have a better performance on the hydrogen evolution reaction (HER), the bulk production of active TMD materials remains a challenging work. This report overcomes those barriers by showing a simple procedure to synthesize TaS2 nanosheets through modifying the arc discharge process. The usage of chloride as the transporting agent reduces the growth period of the formed TaS2 with active edge sites. TaS2 is found to have a uniform thickness (4 nm) with high crystallinity and adopt a 2H polytype (double-layered hexagonal) structure. The as-synthesized TaS2 has superior activity for HER with the potential of 280 mV.

The triangular zone cracks in 2101 duplex stainless steel produced by the vertical continuous caster have troubled company A for a long time. To simulate the temperature and thermal stress distributions in the solidification process of 2101 duplex stainless steel produced by the vertical continuous caster, a two-dimensional viscoelastic–plastic thermomechanically coupled finite element model was established by the secondary development of the commercial nonlinear finite element analysis software MSC Marc. The results show that the thermal stress on the surface reaches a maximum at the exit of the mould, and the highest thermal stresses at the centre of the wide face and the narrow face are 75 and 115 MPa, respectively. Meanwhile, the internal temperature of slab is still higher than the solidus temperature, resulting in no thermal stress. The slab shows different high-temperature strengths and suffers from different stresses at different positions; thus, the risk of cracking also varies. At a location of 6–8 m from the meniscus, the temperature of the triangular zone is 1270–1360 °C and the corresponding permissible high-temperature strength is about 10–30 MPa, while the thermal stress at this time is 60 MPa, which is higher than the high-temperature strength. As a result, triangular zone cracks form easily.

The corrosion behaviors of 316 stainless steel (SS), 316L SS, Inconel 625, Incoloy 825 and Hastelloy C276 were studied in supercritical water (SCW) containing phosphate, sulfate, chloride and/or oxygen. The results show that the alloy corrosion rate in SCW containing oxygen and phosphate was increased by adding sulfate and/or chloride. A two-layer structure of oxide film on 316 SS consisted of an inner layer with Cr-rich oxides (i.e., Cr2O3) and an outer layer rich in phosphates (e.g., FePO4 and Ni3(PO4)2). A three-layer oxide film formed on Incoloy 825 including corrosion products Fe2O3, NiO, FePO4, Ni3(PO4)2 and NiCr2O4, with phosphates in each layer. A two-layer oxide film on Hastelloy C276 was composed of metal oxides in the inner layer and metal oxides as well as phosphates in the outer layer, including Fe2O3, Cr2O3, NiO, MoO2, FePO4, CrPO4, Ni3(PO4)2 and NiCr2O4. The existence of sulfate, chloride, and especially both of them destroyed the formation of water-insoluble phosphates on the oxide film of tested alloy in SCW containing oxygen and phosphate.

Molten salts as heat transfer and storage materials have been used to nuclear energy and concentrated solar power(CSP) applications. In this work, the system of molten salt mixture based on thermodynamic principles was designed as thermal energy storage(TES) materials. The substitutional solution model can be employed to describe the Gibbs energies of all liquid phase. Thermodynamic model parameters for the NaCl-NaNO3-Na2SO4 subsystems were conducted by thermodynamic evaluation and optimization based on experimental phase-equilibria data. Thus, a set of self-consistent thermodynamic database was eventually obtained to reliably calculate the whole phase diagram and thermodynamic properties for the NaCl-NaNO3-Na2SO4 ternary system. The results manifest that the eutectic point of theternary system located at T=280 °C and xNaCl=8.4%, $${x_{NaN{O_3}}}$$ =86.3% and $${x_{N{a_2}S{O_4}}}$$ =5.3%. Moreover, the results predicted were verified experimentally using differential scanning calorimetry(DSC) and the agreement between the measured value[T=(287±2) °C] and predicted value(T=280 °C) was satisfactory. Thus, the thermodynamic calculation method will be used to design and develop novel molten salt mixture as thermal energy storage materials.

Three-dimensional hierarchical porous carbons were synthesized by direct carbonization of glucose and zinc nitrate mixtures. The effects of carbonization temperature on the formation of the microscopic pore structure were studied. When tested in 6 M KOH by three-electrode system, the carbon sample carbonized at 750 °C shows the best electrochemical performance compared to the other samples. High specific capacitance (276 F g−1) is obtained at 0.3 A g−1, and the capacitance still maintains 205 F g−1 when tested at 10 A g−1. Moreover, the sample also possesses good cycling stability with only a loss of 3.7% after 10,000 cycles at 5 A g−1. The facile preparation method and hierarchical porous structure render this carbon material a promising candidate for high-performance supercapacitors application.

In this work, the electrochemical behaviors of SAM2X5 Fe-based amorphous alloy coating and hard chromium coating were comparatively studied in 3.5 wt% NaCl solution. In comparison with the hard chromium coating, the SAM2X5 coating exhibited a wider and stable passive region with lower passive current density in the potentiodynamic polarization and showed a considerably lower current density at different anodic potentials in the potentiostatic polarization. In order to understand the passivation mechanism of the Fe-based amorphous coating, the components of the passive films formed at various polarization potentials were examined by X-ray photoelectron spectroscopy. The synergistic effect of Mo, W, Mn and Cr in the passive films was systemically analyzed. It has been revealed that Mo and W facilitate the formation of compact and stable Cr2O3 passive film at lower potentials, and the substantial enrichment of Mn in the passive film enhances the passivation ability at relatively higher potentials. The deep understanding of the passivation characteristics in multicomponent alloy systems could provide a guide for the design of corrosion-resistant amorphous alloy coatings for engineering applications.

In this paper, we propose a metamaterial based ultra broadband nano-absorber (UBNA) for solar energy harvesting, whose elements consist of a ring column and dual hexagon pillar at the center. In this absorber, the light of shorter wavelengths is harvested at ring column, while the light of longer wavelengths is trapped by dual hexagon pillar. It is found that the average absorptivity of the UBNA is as high as 96% in 300–1300 nm waveband and the UBNA can maintain 95% in the whole visible and near-infrared waveband ranging from 300 to 2000 nm. In addition, the perfect light absorbing capability of the UBNA is independent of the incident light polarization state in the waveband of 300–1300 nm, and it can keep up an average absorptivity of 91% with an large incident angle varying between −60° and 60°. We attribute the perfect absorbing property of UBNA to the synergistic effect of the slow wave effect, Fabry-Perot resonance and the localized surface plasmon resonance enhancement.

Two series of epoxy resins modified with trifluoromethyl-containing poly(amic acid)s and polyimides, respectively, were prepared. The effects of trifluoromethyl group and imide unit on the properties of epoxy resins were investigated. The epoxy resins modified with poly(amic acid)s exhibited better performance because poly(amic acid)s serve as amine curing agent in epoxy resins and form chemical bond with epoxy matrix, thus having higher miscibility with epoxy resin than the epoxy resins modified with polyimides. The glass transition temperatures of the modified epoxy resins were in the range of 88.9–168.2 °C. Compared with unmodified epoxy resin, the modified epoxy resins exhibited better thermal stability with char yield at 800 °C ranging from 18 to 55 %, lower hydrophilicity with water absorption in the range of 0.47–0.95 %, and water contact angle of 94.9–105.0°. The introduction of trifluoromethyl group decreases the surface free energy and hydrophilicity of the modified epoxy resins. The SEM images of the fracture surfaces of the modified epoxy resins showed tough fracture features, indicating the enhancement of toughness of these resins in which imide unit had been introduced.

In this paper, pulsed laser processing technology was used to weld TiB2-enhanced aluminum matrix composites of 2 mm thickness. The effects of welding parameters on welded joints were investigated. The results show that the effect of laser power on the weld forming is obvious. The penetration and width of welded joints were increased while the laser power was increasing. The coefficient of weld forming was changed from 4.19 to 0.997. The base metal was in full penetration when the laser power was 5.5 kW. The hardness of the fusion zone is reached 120 HV when the laser power was 6 kW. It is much higher than that of base metal because of dispersed particles TiB2. The pulse frequency and the welding speed are very important. The good welding formation can be obtained when the parameters meet the formula fd = (3.6–5.4)v. TiB2-enhanced aluminum matrix composites can be well welded with the pulsed laser.