Scalable Production of 2D Non-Layered Metal Oxides through Metal-Organic Gel Rapid Redox Transformation.

Two-dimensional (2D) nonlayered metal compounds with porous structure show broad application prospects in electrochemistry-related fields due to their abundant active sites, open ions/electrons diffusion channels, and faradaic reactions. However, scalable and universal synthesis of 2D porous compounds still remains challenging. Here, inspired by blowing gum, a metal-organic gel (MOG) rapid redox transformation (MRRT) strategy is proposed for the mass production of a wide variety of 2D porous metal oxides. Adequate crosslinking degree of MOG precursor and its rapid redox with NO3- are critical for generating gas pressure from interior to exterior, thus blowing the MOG into 2D carbon nanosheets, which further act as self-sacrifice template for formation of oxides with porous and ultrathin structure. The versatility of this strategy is demonstrated by the fabrication of 39 metal oxides, including 10 transition metal oxides, one II-main group oxide, two III-main group oxides, 22 perovskite oxides, four high-entropy oxides. As an illustrative verification, the 2D transition metal oxides exhibit excellent capacitive deionization (CDI) performance. Moreover, the assembled CDI cell could act as desalting battery to supply electrical energy during electrode regeneration. This MRRT strategy offers opportunities for achieving universal synthesis of 2D porous oxides with nonlayered structures and studying their electrochemistry-related applications.

Enhanced Electromagnetic Wave Absorption of SiOC/Porous Carbon Composites.

Carbon-based materials have been widely explored as electromagnetic (EM) wave absorbing materials with specific surface areas and low density. Herein, novel porous carbon/SiOC ceramic composites materials (porous C/sp-SiOC) were prepared from the binary mixture, which used the low cost pitch as carbon resource and the polysilylacetylene (PSA) as SiOC ceramic precursor. With the melt-blending-phase separation route, the PSA resin formed micro-spheres in the pitch. Then, numerous SiOC ceramic micro-spheres were generated in porous carbon matrices during the pyrolysis process. By changing the percent of SiOC, the microstructure and wave absorption of porous C/sp-SiOC composites could be adjusted. The synergistic effect of the unique structure, the strong interfacial polarization, and the optimized impedance matching properties contributed to the excellent absorption performance of porous C/sp-SiOC composites. The minimum reflection loss for porous C/sp-SiOC absorber reached -56.85 dB, and the widest effective bandwidth was more than 4 GHz with a thickness of only 1.39 mm. This presented research provides an innovative and practical approach to developing high-performance porous carbon-based microwave absorption materials from green chemistry.

Binary Binder for Cf/C-SiC Composites with Enhanced Mechanical Property.

Cf/C-SiC composites have become the preferred material for high-temperature load-bearing applications because of their low density, high strength, and excellent thermal-physical properties. Due to the composite's poor sintering performance, the sintering temperature and pressure required for the preparation of Cf/C-SiC by traditional methods are also relatively high, which limits its engineering application. Herein, based on the precursor-derived ceramic route and C/C composites material preparation process, a binary binder (coal pitch and polysilylacetylene) is developed, which combines a carbon source, SiC precursor, and semi-ceramic SiC filler organically. Then, the SiC phase was successfully introduced into C/C composites by the slurry impregnation-hot pressing sintering method. The prepared Cf/C-SiC composites showed good mechanical properties, with a density of 1.53 g/cm3 and a bending strength of 339 ± 21 MPa. Moreover, the effects of the binary binder on the microstructure, density, and mechanical properties of Cf/C-SiC composites were investigated. This work provides a novel and effective approach to fabricating Cf/C-SiC composites with low density and high strength.

Phase interface engineering of metal selenides heterostructure for enhanced lithium-ion storage and electrocatalysis.

Biphasic or multiphase heterostructures hold attractive prospects in engineering advanced electrode materials for energy-related applications owing to the appealing synergistic effect; however, they still suffer from unsatisfied electrochemical activity and reaction kinetics. Herein, guided by density functional theory calculation, a well-engineered selenides heterostructure with high-density Ni3Se4-NiSe2 biphasic interfaces that fastened in N, O-codoped carbon matrix, was developed for high-performance lithium storage and electrocatalysis. By controlled selenylation of metal-organic framework (MOF), a series of NiSex@C hybrids (Ni3Se4@C, Ni3Se4/NiSe2@C-1, Ni3Se4/NiSe2@C-2, and NiSe2@C) with tunable biphasic components and grain sizes were prepared. Abundant two-phase interfaces with higher interface density are generated inside the Ni3Se4/NiSe2-1 induced by much smaller nanograins in comparison with the Ni3Se4/NiSe2-2, so that significant charge redistribution and faster electrons/Li+ ions transfer kinetics are achieved within the selenides, which are proved by the mutual verification of experiment and theoretical analysis. Benefitting from this optimized heterointerfaces, the Ni3Se4/NiSe2@C-1 electrode manifests reduced polarization, superior rate capability, and prolonged cyclic stability (621.3 mAh g-1 at 1 A g-1 for 1000 cycles; 362.3 mAh g-1 at 4 A g-1 for 2000 cycles) with respect to the Ni3Se4/NiSe2@C-2, as well as excellent performance in LiCoO2//Ni3Se4/NiSe2@C-1 full cell. Detailed electrochemical analysis confirmed rapid electrons/Li+ diffusion rates and more pseudocapacitive energy for the Ni3Se4/NiSe2@C-1. Therefore, the Ni3Se4/NiSe2@C-1 showcases superior hydrogen evolution reaction (HER) and lithium storage performance. This work demonstrates the significance of interface modulation to boost the electrochemical performance of multiphase heterostructures for energy storage and conversion.

A unique two-phase heterostructure with cubic NiSe2 and orthorhombic NiSe2 for enhanced lithium ion storage and electrocatalysis.

Two-phase heterostructures have received tremendous attention in energy-related fields as high-performance electrode materials. However, heterogeneous interfaces are usually constructed by introducing foreign elements, which disturbs the investigation of the intrinsic effect of the two-phase heterostructure. Herein, unique heterostructures constructed with orthorhombic NiSe2 and cubic NiSe2 phases are developed, which are embedded in in situ formed porous carbon from metal-organic frameworks (MOFs) (O/C-NiSe2@C). Precisely-controlled selenylation of MOFs is crucial for the formation of the O/C-NiSe2 heterostructure. The heterogeneous interfaces with lattice dislocations and charge distribution are conducive to the high-speed transfer of electrons and ions during electrochemical processes, so as to improve the electrochemical reaction kinetics for lithium-ion storage and the hydrogen evolution reaction (HER). When used as the anode of lithium-ion batteries (LIBs), O/C-NiSe2@C shows a superior electrochemical performance to the counterparts with only the cubic phase (C-NiSe2@C), in view of the cycling performance (719.3 mA h g-1 at 0.1 A g-1 for 100 cycles; 456.3 mA h g-1 at 1 A g-1 for 1000 cycles) and rate capabilities (344.8 mA h g-1 at 4 A g-1). Furthermore, O/C-NiSe2@C also exhibits better HER properties than C-NiSe2@C, that is, much lower overpotentials of 154 mV and 205 mV in 0.5 M H2SO4 and 1 M KOH, respectively, at 10 mA cm-2, a smaller Tafel slope as well as stable electrocatalytic activities for 2000 cycles/10 h. Preliminary observations indicate that the unique orthorhombic/cubic two-phase heterostructure could significantly improve the electrochemical performance of NiSe2 without additional modifications such as doping, suggesting the O/C-NiSe2 heterostructure as a promising bifunctional electrode for energy conversion and storage applications.

The effect of fluid shear stress on the in vitro degradation of poly(lactide-co-glycolide) acid membranes.

Poly(lactide-co-glycolide) acid (PLGA) has been widely used as a biodegradable polymer material for coating stents or fabricating biodegradable stents. Its mechanism of degradation has been extensively investigated, especially with regard to how tensile and compressive loadings may affect the in vitro degradation of PLGA. Fluid shear stress is also one of the most important factors in the development of atherosclerosis and restenosis. But the effect of fluid shear stress on the degradation process is still unclear. The purpose of this study was to characterize the in vitro degradation of PLGA membranes that experienced different fluid shear stresses in 150 mL of deionized water at 37°C for 20 days. Particular emphasis was given to changes in the viscosity of the degradation solution, as well as the mechanical and morphological properties of the samples. The viscosity of the degradation solution with the mechanical loaded specimens was more severely affected than that of the control group. Increasing the fluid shear stress could accelerate the loss of the ultimate strength of PLGA membranes while it slowed down the change of the tensile elastic modulus in the early period. With regard to morphology, the surface roughness was more obviously reduced in the loaded groups. This indicated that the fluid shear stress could affect the in vitro degradation of PLGA membranes. Therefore, this study could help improve the design of PLGA membranes for biomedical applications. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2016.

Effect of nano-hydroxyapatite-coated magnetic nanoparticles on axonal guidance growth of rat dorsal root ganglion neurons.

Proper extracellular substrate can stimulate neural regeneration in nerve tissue engineering, including magnetic nanoparticles (iron oxide nanoparticles, Fe3 O4 ), but they are always neurotoxic, with low saturation magnetization and so on. These nanomaterials cannot be used to stimulate the growth and elongation of axons. Therefore, this work attempts to overcome these deficiencies. Nano-hydroxyapatite (n-HA) coated magnetic nanoparticles were using an ultrasound-assisted co-precipitation method. X-ray diffraction and transmission electron microscopy were used to characterize the structure and chemical composition of the produced samples. These synthesized nanomaterials were added into the primary cultured dorsal root ganglion (DRG) neurons; our results showed that n-HA-coated magnetic nanoparticles (Fe3 O4 +n-HA) can effectively increase cell viability and promote axonal elongation, which enhanced saturation magnetization. In addition, we demonstrated that axonal guidance cues Netrin-1 increase significantly after n-HA-coated magnetic nanoparticles treatment by Western blots assay. n-HA-coated magnetic particles maybe applied to enhance or accelerate nerve regeneration, and it may provide guidance for regenerating axons in future.

Ultrasound-assisted fabrication of a biocompatible magnetic hydroxyapatite.

This work describes the fabrication and characterization of a biocompatible magnetic hydroxyapatite (HA) using an ultrasound-assisted co-precipitation method. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and transmission electron microscopy (TEM) were used to characterize the structure and chemical composition of the produced samples. The M-H loops of synthesized materials were traced using a vibrating sample magnetometer (VSM) and the biocompatibility was evaluated by cell culture and MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay. Furthermore, in vivo histopathological examinations were used to evaluate the potential toxicological effects of Fe3O4-HA composites on kidney of SD rats injected intraperitoneally with Fe3O4-HA particles. The results showed that magnetic iron oxide particles first replace OH ions of HA, which are parallel to the c axis, and then enter the HA crystal lattice which produces changes in the crystal surface of HA. Chemical bond interaction was observed between PO4³â» groups of HA and iron ions of Fe3O4. The saturation magnetization (MS ) of Fe3O4-HA composites was 46.36 emu/g obtained from VSM data. Cell culture and MTT assays indicated that HA could affect the growth and proliferation of HEK-293 cells. This Fe3O4-HA composite produced no negative effects on cell morphology, viability, and proliferation and exhibited remarkable biocompatibility. Moreover, no inflammatory cell infiltration was observed in kidney histopathology slices. Therefore, this study succeeds to develop a Fe3O4-HA composite as a prospective biomagnetic material for future applications.

Preparation and characterization of NiW-nHA composite catalyst for hydrocracking.

The synthesis, characterization and catalytic capability of the NiW-nano-hydroxyapatite (NiW-nHA) composite were investigated in this paper. The NiW-nHA catalyst was prepared by a co-precipitation method. Then Fourier transform infrared (FT-IR) spectroscopy, transmission electron microscopy (TEM), X-ray diffraction (XRD) and energy dispersive spectroscopy (EDX) were used to analyze this material. In addition, the catalytic capacity of the NiW-nHA composite was also examined by FT-IR and gas chromatography (GC). The results of FT-IR analysis indicated that Ni, W and nHA combined closely. TEM observation revealed that this catalyst was needle shaped and the crystal retained a nanometer size. XRD data also suggested that a new phase of CaWO(4) appeared and the lattice parameters of nHA changed in this system. nHA was the carrier of metals. The rates of Ni/W-loading were 73.24% and 65.99% according to the EDX data, respectively. Furthermore, the conversion of 91.88% Jatropha oil was achieved at 360 °C and 3 MPa h(-1) over NiW-nHA catalyst. The straight chain alkanes ranging from C(15) to C(18) were the main components in the production. The yield of C(15)-C(18) alkanes was up to 83.56 wt%. The reaction pathway involved hydrocracking of the C═C bonds of these triglycerides from Jatropha oil. This paper developed a novel non-sulfided catalyst to obtain a "green biofuel" from vegetable oil.