查看更多>>摘要：In this study,Fe-C core-shell nanoparticles with identical metal core sizes and C shell thicknesses but varying degrees of graphitization of C shells were fabricated using metal-organic chemical vapor depo-sition and subsequent annealing.Due to the identical metal core,these nanoparticles exhibite a similar permeability,but significantly varying permittivity depending on how much C shells have been graphi-tized.It was discovered that proper graphitization of Fe-C nanoparticles annealed at 1350 ℃ can pro-duce excellent microwave absorption(MA),decent dielectric loss tangent in high frequency region,and moderately strong dielectric loss and attenuation properties.Furthermore,the threshold value of 1/ω is discovered to be a crucial parameter in the theoretical analysis of nonlinear behavior of polarization loss,and thus MA performance of the nanoparticles.This research offers a useful method for creating metal-C nanoparticles with various levels of C shell graphitization.It also provides a clear answer to the crucial question of how the level of C shell graphitization affects the MA performance of metal-C nanoparticles.These results may serve as a reference for the development and mechanism analysis of highly effective metal-C based absorbers.
查看更多>>摘要：As-cast alloys often require complex thermomechanical processing to obtain a hierarchical structure to achieve a good combination of strength and ductility.Here in this work,a novel hierarchical Fe27Ni35Cr18.25Al13.75Co2Ti2Mo2 high-entropy alloy(HEA)with ultra-high tensile strength and excellent ductility was fabricated by direct casting.The as-cast alloy exhibits hierarchical structure with an ul-trafine lamellar microstructure(ULM),ultrafine rhombus microstructure(URM),ultrafine vermicular mi-crostructure(UVM),nanosized precipitates and spinodal decomposition(SP)that develops during casting and cooling.The incompatibility of face-centered cubic(FCC)and body-centered cubic(BCC)phases in the deformation process leads to heterogeneous deformation-induced(HDI)hardening,which brings the alloy a tensile yield strength(YS)of～1056 MPa,an ultimate tensile strength(UTS)of～1526 MPa and a total elongation(El)of～15.6％.Additionally,the numerous interfaces generated by the hierarchical structure absorb the energy during deformation,effectively retarding the dislocation motion and causing strong work-hardening.
查看更多>>摘要：Laser powder bed fusion(L-PBF)has been used to fabricate biodegradable Mg implants of WE43 alloy,but the degradation is too fast compared with the term bone reconstruction.Previous studies show that high temperature oxidation(HTO)can successfully inhibit the degradation of WE43 alloy.In this work,the influence of HTO on L-PBF samples of WE43 alloy was investigated regarding tensile,compressive,and abrasive resistance,as well as in vitro cytotoxicity,cell proliferation,hemolysis,and osteogenesis.Compared with the as-built L-PBF samples,HTO increased grain size and grain texture,stabilized and coarsened precipitates,and caused discontinuous static recrystallization in the matrix.The oxide layer at the surface of the HTO samples improved surface roughness,hydrophilia,hardness,and abrasive resis-tance.The tensile strength decreased slightly from 292 to 265 MPa,while the elongation substantially increased from 10.97％to 16.58％after HTO.The in vitro cell viability,cell proliferation,hemolysis,and osteogenic effect were considerably enhanced due to the improvement of surface quality and the initial inhibition of excessive Mg2+releasement.Overall,HTO is of great benefit to the surface performance,ductility,and biocompatibility of WE43 alloy fabricated by L-PBF for biodegradable applications.
查看更多>>摘要：Catalytic CoFe2O4 and solar-thermal carbon nanotube decorated bamboo fabrics(CCBF)are fabricated for integrating efficient solar steam generation from wastewater with catalytic degradation of its organic con-taminants.Thanks to the numerous porous channels and polar groups of bamboo fabric and the efficient solar-thermal energy conversion of black carbon nanotubes,the porous and hydrophilic CCBF exhibits fast upward transport of water,efficient solar light absorption,and high solar-thermal energy conversion effi-ciency.The decorated CoFe2O4 not only enhances the solar-thermal energy conversion efficiency of CCBF but also activates potassium peroxymonosulfate to generate abundant highly active species for catalytic degradation of bisphenol A(BPA).Furthermore,folding the CCBF into a peak-like 3D evaporator can en-hance solar energy utilization,and gain environmental energy for promoting solar-thermal water evapo-ration and catalytic degradation performances.The 3D CCBF evaporator achieves a water evaporation rate of 2.72 kg m-2 h-1 under 1-sun irradiation.Meanwhile,100％of the BPA in the seawater can be degraded within 10 min.An exceptional high purification efficiency of 27.72 kg m-2 h-1 is achieved with the 3D evaporator during a long-term treatment of BPA-containing seawater under 1-sun irradiation.This work demonstrates efficient purification of seawater/wastewater with both metal ions and organic pollutants by simultaneous solar-thermal evaporation of water and catalytic degradation of organic pollutants.
查看更多>>摘要：Composites featuring negative permittivity have garnered significant attention for their potential in novel capacitance designs,coil-less electrical inductors,and electromagnetic shielding applications.In this study,we prepared polyvinylidene fluoride(PVDF)matrix composites filled with ZrO2/C nanoparticles de-rived from metal-organic frameworks(MOFs)via a hot-pressing method.With an increase in the ZrO2/C content to 30 wt.％,electrical percolation was observed,accompanied by a transition mechanism from hopping conduction to metal-like conduction.This enabled the realization of ZrO2/C/PVDF composites with tailorable negative permittivity properties,attributed to the plasmonic oscillation of free electrons in the composites beyond the percolation threshold(30 wt.％).Furthermore,the permittivity transition along to a shift in the electrical behavior of the percolative composites from capacitive to inductive.We explored the regulatory mechanism behind the negative permittivity in this random composite system,and our findings highlight the potential of these tunable negative permittivity media as promising candi-dates for diverse electromagnetic applications.
查看更多>>摘要：The zero-dimensional perovskite composite Cs4PbBr6/CsPbBr3 has attracted significant attention for its remarkable photoluminescence(PL),which remains highly effective even in solid state.This work presents a detailed analysis of the steady-state and time-resolved PL(TRPL)behavior of millimeter-scale Cs4PbBr6/CsPbBr3 crystals over a temperature range of 80 to 360 K,which covers exciton binding en-ergy,phonon energy,and PL peak energy shifting with increasing temperature.According to the results,Cs4PbBr6/CsPbBr3 exhibits high exciton binding energy and phonon energy,with calculated values of 358.7 and 94.8 meV,respectively.Specifically,when the temperature is below～235 K,thermal expan-sion dominates to influence the TRPL and peak energy,whereas electron-phonon interaction becomes the dominant factor as temperature rises from 235 to 325 K.It is found that Cs4PbBr6/CsPbBr3 has a PL behavior similar to CsPbBr3,and characterization and TRPL results demonstrate that nanometer-scale CsPbBr3 crystals embed in the Cs4PbBr6 bulk matrix.Meanwhile,a white light-emitting diode(WLED)device based on Cs4PbBr6/CsPbBr3 with luminous efficiency of 64.56 Im/W is fabricated,and its color coordinate is measured as(0.34,0.31)under 20 mA,which is in close proximity to the standard white color coordinate.Moreover,the color gamut of the device is measured as 128.66％of the National Televi-sion Systems Committee(NTSC).The WLED electroluminescence(EL)spectra show high Correlated Color Temperature(CCT)stability for the working current varying from 5 to 100 mA,and after continuous oper-ation for 12 h,the EL intensity decreases and stabilizes at～70％of the initial EL intensity.These findings suggest that Cs4PbBr6/CsPbBr3 crystals are a promising candidate for WLEDs.
查看更多>>摘要：Herein,two novel 3D porous Ni-based N doped carbon heterojunctions(NiS2@NC or Ni2P@NC)were suc-cessfully prepared through in situ carbonization and sulfurization or phosphorization by using flower-like Ni-based zeolite imidazolium framework as a precursor.Physiochemical and photoelectrochemical prop-erties were investigated to explore photoinduced charge separation and transfer in the heterojunction.Meanwhile,the photo/electrocatalytic hydrogen evolution performances were evaluated systematically.In contrast to the controlled Ni-ZIF and Ni@NC composites,the expected flower-like NiS2@NC compounds show significantly enhanced photo/electrocatalytic hydrogen evolution performances,which is 13.8 times that of Ni-ZIF and 1.8 times that of Ni@NC.Furthermore,a phosphorus-decorated composite(Ni2P@NC)was synthesized for better comparison,which also displays apparently improved photo/electrocatalytic hydrogen evolution activities.The findings present that the synergistic effect of S doping and semicon-ducting NiS2 formation take responsibility for the enhancement of H2 generation over the NiS2@NC hy-brids.This work can provide a new strategy to construct efficient ZIFs-based photo/electrocatalysts with high performance of H2 production.
查看更多>>摘要：In this work,Ag/Ag2Se composite films with excellent thermoelectric(TE)properties and flexibility are prepared based on a simple one-pot method.By adjusting the nominal ratios of Ag/Se,an optimal Ag/Ag2Se composite film shows a large power factor of～2275 μW m-1 K-2 at 300 K.Such an outstand-ing TE performance of the composite film is due to the unique microstructure and the synergistic effect between the Ag and Ag2Se.Meanwhile,the composite film also shows outstanding flexibility(～91.8％of the initial electrical conductivity is maintained,and the S is unchanged after 1500 bending cycles with a bending radius of 4 mm).Furthermore,a 4-leg flexible TE generator assembled with the optimal film produces a voltage of 14.06 mV and 4.96 μW at a temperature difference of 30.4 K.This work provides a new inspiration for the preparation of flexible Ag2Se-based films with excellent TE performance near room temperature.
查看更多>>摘要：Two-dimensional(2D)materials have come to light due to their unique thickness that owns abundant exposed edges with enhanced electrocatalytic properties.2D molybdenum disulfide(MoS2)nanosheet has aroused considerable attention due to its tunable surface chemistry and high electrochemical sur-face area.Nonetheless,several shortcomings associated with MoS2,such as its naturally existing semi-conducting 2H phase,which has limited active sites due to the inert basal plane,restrict its application in water electrocatalysis.Taking into account the benefits of the 1T/2H phase of MoS2,as well as the importance of engineering 2D/2D heterojunction interface for boosted electrocatalysis,metallic Ti3C2Tx was integrated with 1T/2H MoS2 to develop 2D/2D 1T/2H MoS2/Ti3C2Tx heterostructured nanocompos-ites.Herein,with only 25％of the intercalating agent,1T/2H MoS2 with the highest 1T phase content of～82％was successfully synthesized.It was further incorporated with 1 wt％of Ti3C2Tx through a com-bination of ultrasonication and mechanical stirring process.The 1T/2H MoS2(25D)/Ti3C2Tx-1(MTC-1)manifested outstanding electrocatalytic performance with an overpotential and Tafel slope of 280 mV(83.80 mV dec-1)and 300 mV(117.2 mV dec-1),for catalyzing acidic and alkaline medium HER,respec-tively.Pivotally,the as-prepared catalysts also illustrated long-term stability for more than 40 h.The coupling method for the 2D nanosheets is crucial to suppress the oxidation of Ti3C2Tx and the restack-ing issue of 2D nanosheets.The superior HER activity is ascribed to the synergistic effect between the heterostructure,enhancing the electronic structure and charge separation capability.The intrinsic prop-erty of the catalyst further confirms by turnover frequency(TOF)calculation.As such,this research paves the way for designing high-efficiency 2D electrocatalysts and sheds light on the further advancement of tunable 2D electrocatalysts for robust water splitting and beyond.
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