Ni1−xCoxSe2?C/ZnIn2S4 Hybrid Nanocages with Strong 2D/2D Hetero-Interface Interaction Enable Efficient H2-Releasing Photocatalysis

Designing a semiconductor-based heterostructure photocatalyst for achieving the efficient separation of photogenerated electron-hole pairs is highly important for enhancing H₂ releasing photocatalysis. Here, a new class of Ni_1−xCo_xSe₂–C/ZnIn₂S₄ hierarchical nanocages with abundant and compact ZnIn₂S₄ nanosheets/Ni_1−xCo_xSe₂^ C nanosheets 2D/2D hetero–interfaces, is designed and synthesized. The constructed heterostructure photocatalyst exposes rich hetero-junctions, supplying the broad and short transfer paths for charge carriers. The close contacts of these two kinds of nanosheets induce a strong interaction between ZnIn₂S₄ and Ni_1−xCo_xSe₂ C, improving the separation and transfer of photo-generated electron-hole pairs. As a consequence, the distinctive Ni_1−xCo_xSe₂ C/ZnIn₂S₄ hierarchical nanocages without using additional noble-metal cocatalysts, display remarkable H₂-relaesing photocatalytic activity with a rate of 5.10 mmol g⁻¹ h⁻¹ under visible light irradiation, which is 6.2 and 30 times higher than those of fresh ZnIn₂S₄ nanosheets and bare Ni_1−xCo_xSe₂ C nanocages, respectively. Spectroscopic characterizations and theory calculations reveal that the strong interaction between ZnIn₂S₄ and Ni_1−xCo_xSe₂ C 2D/2D hetero-interfaces can powerfully promote the separation of photo-generated charge carriers and the electrons transfer from ZnIn₂S₄ to Ni_1−xCo_xSe₂ C.     

Engineering Bioactive M2 Macrophage-Polarized Anti-Inflammatory,Antioxidant, and Antibacterial Scaffolds for Rapid Angiogenesis and Diabetic Wound Repair

Diabetic wound healing still faces great challenges due to the excessive inflammation, easy infection, and impaired angiogenesis in wound beds. The immunoregulation of macrophages polarization toward M2 phenotype that facilitates the transition from inflammation to proliferation phase has been proved to be an effective way to improve diabetic wound healing. Herein, an M2 phenotype-enabled anti-inflammatory, antioxidant, and antibacterial conductive hydrogel scaffolds (GDFE) for producing rapid angiogenesis and diabetic wound repair are reported. The GDFE scaffolds are fabricated facilely through the dynamic crosslinking between polypeptide and polydopamine and graphene oxide. The GDFE scaffolds possess thermosensitivity, self-healing behavior, injectability, broad-spectrum antibacterial activity, antioxidant and anti-inflammatory ability, and electronic conductivity. GDFE effectively activates the polarization of macrophages toward M2 phenotype and significantly promotes the proliferation of dermal fibroblasts, the migration, and in vitro angiogenesis of endothelial cells through paracrine mechanisms. The in vivo results from a full-thickness diabetic wound model demonstrate that GDFE can rapidly promote the diabetic wound repair and skin regeneration, through fast anti-inflammation and angiogenesis and M2 macrophage polarization. This study provides highly efficient strategy for treating diabetic wound repair through designing the M2 polarization-enabled anti-inflammatory, antioxidant, and antibacterial bioactive materials.     

Nitrate Additives Coordinated with Crown Ether Stabilize Lithium Metal Anodes in Carbonate Electrolyte

Lithium metal anodes (LMAs) are promising for next-generation batteries but have poor compatibility with the widely used carbonate-based electrolytes, which is a major reason for their severe dendrite growth and low Coulombic efficiency (CE). A nitrate additive to the electrolyte is an effective solution, but its low solubility in carbonates is a problem that can be solved using a crown ether, as reported. A rubidium nitrate additive coordinated with 18-crown-6 crown ether stabilizes the LMA in a carbonate electrolyte. The coordination promotes the dissolution of NO₃⁻ ions and helps form a dense solid electrolyte interface that is Li₃N-rich which guides uniform Li deposition. In addition, the Rb (18-crown-6)⁺ complexes are adsorbed on the dendrite tips, shielding them from Li deposition on the dendrite tips. A high CE of 97.1% is achieved with a capacity of 1 mAh cm⁻² in a half cell, much higher than when using the additive-free electrolyte (92.2%). Such an additive is very compatible with a nickel-rich ternary cathode at a high voltage, and the assembled full battery with a cathode material loading up to 10 mg cm⁻² shows an average CE of 99.8% over 200 cycles, indicating a potential for practical use.     

Surface modification of superfine SiC powders by ternary modifiers-KH560/sodium humate/SDS and its mechanism

SiC is a promising functional ceramic material with many great properties. High concentrated SiC slurry with excellent rheology and stability is required in some processes of ceramic forming. In this work, the dispersion of SiC powders was obviously improved by ternary modifiers: γ-(2,3-epoxypropoxy) propytrimethoxysilane (KH560), sodium humate and sodium dodecyl sulfate (SDS). Modified SiC slurry showed the lowest viscosity of 0.168 Pa s at a solid content of 50 vol%. The maximum absolute value of zeta potential of SiC increased from 47.3 to 61.6 mV by modification. Sedimentation experiments showed that a highly stable suspension of modified SiC was obtained at pH 10. SiC green body with high density of 2.643 g/cm³ was prepared with modified powders by slip casting. X-ray photoelectron spectra (XPS) and thermogravimetry (TG) measurements indicated the adsorption of modifiers on SiC surface. Therefore, modified SiC powders could stably disperse in aqueous media due to the increase of electrosteric repulsion between particles. The novel strategy used in this study could further improve the dispersion of SiC powders.     

Wear and thermal behavior of basalt fiber reinforced rice husk/polyvinyl chloride composites

Plant fiber reinforced polymer composites (PFRPs) in practical application are often subjected to both complex friction and variable temperature environments. The present work explores the possibility of reinforcing rice husk/polyvinyl chloride (RH/PVC) composites with basalt fibers (BF) for developing a new wear resistant material with improved thermal stability. The results showed that the structural strength and wear resistance of the composites increased at first and then decreased with an increasing ratio of BF/RH, the highest value occurred at a BF/RH ratio of 8/42. The thermal stability of composites had a positive relationship with BF/RH ratio. The composites added with BF all possessed improved performance in comparison with unadded composites. Hence, the findings of this article proposed some new perspectives on improving the wear resistance and thermal stability of PFRPs that would broaden their practical application.     

Fabrication and upconversion luminescence properties of Er:SrF2 transparent ceramics compared with Er:CaF2

SrF₂ transparent ceramic is a promising upconversion material due to the low phonon energy. The effect of different sintering temperatures on Er:SrF₂ transparent ceramics was investigated. The suitable sintering temperature for Er:SrF₂ transparent ceramics was 900 °C by hot-pressed sintering in this study. High quality of Er:SrF₂ transparent ceramics with different doping concentrations were obtained. The upconversion luminescence spectra and decay behavior were compared between Er:SrF₂ and Er:CaF₂ transparent ceramics with different Er³⁺ doping concentration. The green emission of 5 at.% Er:SrF₂ ceramic was much stronger than that of 5 at.% Er:CaF₂ ceramic, while the red emission of Er:SrF₂ ceramic was almost the same as that of Er:CaF₂ ceramic. The upconversion luminescence lifetime of Er:SrF₂ transparent ceramics was longer than that of Er:CaF₂.All the results indicated Er:SrF₂ transparent ceramics was a candidate for green fluorescent upconversion materials.     

Electrochemical performance of in situ LiFePO4 modified by N-doped graphene for Li-ion batteries

LiFePO₄ modified by N-doped graphene (NG) with a three-dimensional conductive network structure was synthesized via a one-step in situ hydrothermal method. The effects of N amount of NG on the phase structure, morphology, and electrochemical properties of LiFePO₄ are investigated in this study. X-ray diffraction (XRD) results show that doping suitable N amounts in NG do not alter the crystal structure of LiFePO_4, and scanning electron microscopy (SEM) images show that NG can slightly reduce the particle size of LiFePO₄. The high-resolution transmission electron microscopy (HRTEM) results show that the LiFePO₄ particles are well covered and connected by NG. The electrochemical performance confirms that LiFePO₄ modified by 20% N-doped graphene (named LFP/NG-4) displays a perfect specific capacity of 166.6 mAh·g^?1 at a rate of 0.2C and can reach 125 mAh·g^?1 at a rate of 5 C. Electrochemical impedance spectroscopy (EIS) results illustrate that the charge transfer resistance value of the LFP/NG-4 composite is only 58.6 Ω, which is very low compared with LiFePO₄. Cyclic voltammetry (CV) tests indicate that the addition of 20% N-doped graphene can effectively reduce electrode polarization and improve reversibility. The LFP/NG-4 composite with a three-dimensional conductive network structure can be regarded as a promising cathode material for Li-ion batteries.     

Effect of environmental pressure on the microstructure of YSZ thermal barrier coating via suspension plasma spraying

Suspension plasma spraying (SPS) as a potential technique to prepare thermal barrier coatings (TBCs) has been attracting more and more attention. However, most reports on SPS were carried out in the atmosphere. Given the unique features of in-flight particles and plasma jets under low pressure, the resulting coatings are expected to be different from those under atmospheric pressure. In this article, yttria-stabilized zirconia (YSZ) thermal barrier coatings were prepared using suspension plasma spraying under different environmental pressures. The results show that as the environmental pressure decreased, the column-like structural coating turned into a vertical crack segmented structure, as well as a dramatic decrease in surface roughness. More nanoparticle agglomerates were formed in the coating under lower environmental pressures. The real porosity of the coating increased with a decrease in environmental pressure.     

Understanding grain refining and anti Si-poisoning effect in Al-10Si/Al-5Nb-B system

Grain refinement is critical for fabricating high-quality Al-Si casting components in the application of automobile and aerospace industries,while the well-known Si-poisoning effect makes it difficult.Nbbased refiners offer an effective method to refine Al-Si casting alloys,but their anti Si-poisoning capability is far from being understood.In this work,the grain refining mechanism and the anti Si-poisoning effect in the Al-10 Si/Al-5 Nb-B system were systematically investigated by combining transmission electron microscope,first-principles calculations,and thermodynamic calculations.It is revealed that NbB₂provides the main nucleation site in the Al-10 Si ingot inoculated by 0.1 wt.%Nb Al-5 Nb-B refiner.The exposed Nb atoms on the(0001)NbB₂and(1-100)NbB₂surface can be substituted by Al to form(Al,Nb)B₂intermedia layers.In addition,a layer of NbAl₃-like compound(NbAl₃')can cover the surface of NbB₂with the orientation relation of(1-100)[11-20]NbB_2//(110)[110]NbAl₃'.Both of the(Al,Nb)B₂and NbAl₃'intermedia layers contribute to enhancing the nucleation potency of NbB₂particles.These discoveries provide fundamental insight to the grain refining mechanism of the Nb-B based refiners for Al-Si casting alloys and are expected to guide the future development of stronger refiners for Al-Si casting alloys.     

Altered age-hardening behavior in the ultrafine-grained surface layer of Mg-Zn-Y-Ce-Zr alloy processed by sliding friction treatment

To gain insight into the ageing behavior of ultrafine grain(UFG)structure,the precipitation phenom-ena and microstructural evolutions of Mg-6Zn-1Y-0.4Ce-0.5 Zr(wt.％)alloy processed by sliding friction treatment(SFT)were systematically studied using hardness texting,transmission electron microscopy(TEM)equipped with high-angle annular dark-field scanning(HADDF-STEM),X-ray diffraction(XRD)and XRD line broadening analysis.The microhardness of the SFT-processed(SFTed)sample initially decreases from 109.6 HV to 104.8 HV at ageing for 8 h,and then increases to the peak-ageing point of 115.4 HV at 16 h.Subsequently,it enters the over-aged period.The un-SFTed sample,as the counterpart,follows a regular ageing behavior that increases from 89.9 HV to 99.6 HV when ageing for 12 h,and then drops.A multi-mechanistic model is established to describe the strengthening due to grain refinement,disloca-tion accumulation,precipitation etc.The analysis reveals that the temperature sensitive UFG structure has an obvious grain coarsening effect,which arouses the soft phenomenon in the early ageing stage.But precipitation hardening provides an excellent hardness enhancement for overcoming the negative influ-ence and helping to reach the peak-aged point.In our microstructural observations,a lot of equilibrium ultrafine MgZn2 precipitates precipitate along dislocations because defects can provide the favorable conditions for the migration and segregation of solute atoms.