查看更多>>摘要：In this paper,a two-dimensional covalent organic framework material(named HDU-27)with thiazole structure and π-π conjugation has been successfully synthesized using the ligands tri acetaldehyde-based methoxyphenyl and benzo[1,2-d∶4,5-d]thiazole-2,6-diamine in an ammonia-formaldehyde condensation reaction and applied to the photocatalytic reduction study of chromium(Cr).The photocatalytic experiments showed that HDU-27 had an excellent photocatalytic reduction of Cr(Ⅵ)with a high Cr(Ⅵ)reduction efficiency of 99.5％at pH=2 for 60 min.In the presence of interfering ions,HDU-27 exhibited excellent selectivity for Cr(Ⅵ).Mechanistic experi-ments and electron spin resonance characterization identified e-and·O2-radicals as the main active species in Cr(Ⅵ)photocatalytic reduction.In addition,the photocatalytic rate of HDU-27 was significantly accelerated in the Cr(Ⅵ)/organic pollutant(RhB,MB,MO)mixed system due to the oxidation of the organic matter and the increase in the separation of photogenerated e--h+.The cycling experiments demonstrated the excellent reduction stability and recyclability of HDU-27 in the photocatalytic reduction of Cr(Ⅵ).HDU-27 is an excellent photocatalyst with potential application for removing organic pollutants and heavy metal ions from contaminated wastewater.
查看更多>>摘要：In this paper,molecular dynamics simulations are employed to investigate the temperature,stress distribution,microstructure and evolution of dislocations in single-crystal Ni-based superalloys during femtosecond laser drilling of micro-holes.The results indicate that the temperature and stress variations in the model system increase with the increment of laser energy density.The pulse width has a relatively low effect on temperature and stress variations.At the same time,an increase in dislocations is primarily related to energy density and stress distribution.The number of dislocations increases with the energy density,with the 1/6<112>dislo-cation showing the highest increase ratio.The densest concentration of dislocations occurs at the hole walls.Dislocations and stacking faults gradually penetrate the precipitate phase under the influence of temperature and reach a stable state as the relaxation time increases.The above research findings provide important theoretical guidance for understanding the microstructure evolution and changes in the mechanical properties of single-crystal Ni-based superalloys during femto-second laser processing of micro-holes.
查看更多>>摘要：In this work,2195 Al-Li alloys with various precipitation microstructures were obtained by homogenization treatment followed by air-cooling(AC),discontinuous cooling(DC),and furnace-cooling(FC),and then tested by hot compression at different temperatures.The results show that the flow stresses of all specimens decrease with temperature and the peak stresses of AC,DC and FC specimens decrease in order at the same temperature.For FC samples,coarse pre-precipitates diminish the deformation resistance due to the reduction of solid solution strengthening and precipitation strengthening.Dynamic softening at low temperatures is significantly greater than that at high temperatures,except for the anomalous softening of the FC specimen at 520 ℃ due to stress release by cracks.At 370-420 ℃,the dynamic softening of the AC specimen is more significant than the other samples,resulting from dynamic precipitation and precipitate coarsening.Furthermore,there is considerable dynamic recrystallization(DRX)in FC samples and not in AC and DC samples,although their precipitates coarsen to similar levels at low temperatures.This suggests that DRX is associated with the particle-stimulated nucleation mechanism by regularly arranged precipitates.The banded or regularly arranged precipitates divide the Al matrix into multiple confined units,hindering dislocations and(sub)grain boundary movement,and thus promoting the development of sub-grains and DRX.
查看更多>>摘要：Developing the efficient and low-cost electrocatalysts derived from biomass is a desired solution to address economy and sustainability challenges of hydrogen production from water electrolysis due to utilizing metal-based catalysts.Herein,the peeled cornstalk-derived porous carbon plates synthesized by salt template-assisted high-temperature pyrolysis are utilized as self-supported metal-free electrocatalysts to unravel the oxygen evo-lution activity for alkaline water splitting.The resultant PC-700-10 honeycomb carbon catalyst exhibits the su-perior electrocatalysis for oxygen evolution owning to its high specific surface area of 52.0 m2 g-1,suitable micro-and meso-pores,electron-withdrawing pyridinic-N moiety and appropriate balance between hydrophilicity and electroconductivity.Theoretical calculations reveal that the largest energy barrier of forming*OOH limits the OER rate and*OH oxidation generates the energetically more favorable epoxide intermediate.This finding opens the way to construct the hopeful metal-free OER electrocatalysts via regulating their intrinsic structure,and in-spires the applications of waste biomass in the energy-correlated fields.
查看更多>>摘要：Hydrogen has been widely recognized as a promising new renewable energy source.Developing safe and efficient hydrogen storage technologies is crucial for scaling up hydrogen energy applications.AB2-type Ti-Mn-based hydrogen storage alloys have excellent kinetic and activation properties,but their comprehensive hydrogen storage performance,especially the hydrogen storage capacity,platform pressure,and cycling stability of low-cost Ti-Mn-based alloys without V,needs to be further optimized.Hence,the hydrogen storage properties of the Ti1.xZrxMn0.9Cr0.7Fe0.1(x=0.05,0.16,0.20,0.25)were systematically studied.All of the series alloys contained a single C14-type Laves phase structure.Increasing the substitution of Zr for Ti resulted in higher hydrogen storage capacities and lower plateau pressures.Notably,the effective hydrogen storage capacity of x=0.16 alloy is significantly higher than that of the other alloys,and its platform pressure is the most suitable.This alloy achieved a hydrogen content of 1.8 wt％and demonstrated excellent cycling stability,retaining 98.6％of its capacity after 100 cycles.This study provides a theoretical guideline for optimizing the properties of low-cost TiMn-based alloys without V.
查看更多>>摘要：Rational design and production of materials for highly effective and environmental-friendly electrocatalytic hydrogen evolution reaction(HER)play a pivotal role in advancing renewable energy utilization.Structural engineering of noble metal nanomaterials can significantly boost catalytic performance through atomic rear-rangement,electronic structure modification and surface reactivity modulation.Here,RuNi alloy is synthesized using a novel high temperature liquid shock method(HTLS)with instant Joule heating treatment at 1073 K under the mixed atmosphere of Argon(Ar)and CO.The synthesis process involves an aqueous solution containing metal precursors,capping agents,reductant agents and carbon black.Particularly,the as-prepared RuNi-HTS nano-structures with hexagonal close-packed(hcp)phase demonstrate impressive electrocatalytic HER activity in alkaline conditions,requiring only 28 mV of overpotentials at a current density of 10 mA cm-2.Note that the Tafel slope is 159.2 mV dec-1.Furthermore,this versatile HTLS method can be extended to synthesize other catalysts,including Ru-HTS,PtRu,and PtZn,all of which show commendable performance for HER as well.This study lays the groundwork for the strategic design and high-throughput synthesis of novel materials with fine-tuned structure and refined size,enabling highly efficient and environmental-friendly electrocatalysis.
查看更多>>摘要：In this study,we synthesized pure ZnO and Co3O4-ZnO precursors with varied Co,Zn ratios via solvothermal method,and then the precursors were calcined at 400 ℃ for 2 h in a muffle furnace under air to obtain composites for acetone detection.The structure,morphology,elemental composition,microstructure and chemical state of these materials were systematically studied by various characterization techniques.Additionally,we also eval-uated the gas sensing performance of the composites-based sensors,focusing on optimal operating temperature,baseline resistance,repeatability,stability,selectivity,response/recovery time,and resistance under varying relative humidity.The findings reveal that 3％Co3O4-ZnO-based sensor exhibit the highest response value to 100 ppm acetone(74),showing an enhancement of approximately 9.3 times compared to the pure ZnO-based sensor(8).Furthermore,the 3％Co3O4-ZnO-based sensor demonstrate the advantages of rapid response/re-covery times(15 s/2 s),outstanding selectivity,and remarkable stability.The gas sensing mechanism of the composite material is also discussed in detail,which provides insights into the observed enhancement of gas sensing performance.It provides an idea for the follow-up study on gas sensing performance of acetone sensors.
查看更多>>摘要：Three-dimensional(3D)quantitative characterization of defects in superalloys is an important way to promote the ability of material design and service life prediction.In this work,3D spatial distribution of defects for Inconel 625 superalloy manufactured by laser additive manufacturing(LAM)is carried out deep learning(DL)image iden-tification technology and 3D image reconstruction.Firstly,computer tomography(CT)technology was used to obtain continuous slice images of sample.The U-net DL algorithm was applied to intelligently identify material defects in the continuous slices.On this basis,quantitative identification and analysis of spatial defect positions and typical sizes is achieved by using 3D reconstruction software.Compared with traditional threshold seg-mentation(TS)techniques,the defect recognition rate has significantly improved from 61.90％to 95.00％.This work provides a promising characterization method for efficient characterizing alloy defects and damage espe-cially during material performance evaluation.
查看更多>>摘要：The presence of benzene and toluene in groundwater poses a serious threat to both aquatic ecosystems and human health.The electrochemical removal of these contaminants is primarily hindered by the low generation yield of reactive oxygen species(ROS).Herein,polytetrafluoroethylene(PTFE)was electrodeposited onto the surface of Sb-SnO2-doped TiO2 nanotubes(TNT/Sb-SnO2/5PTFE-300)to enhance electrochemical activity.The resulting nanoelectrode achieved removal efficiencies of 96.2％for benzene and 97.6％for toluene.The minimal variation in the degradation of benzene and toluene following 8 cycles of use verified its stability.Experiments confirmed that·OH was the primary ROS.Hydrophobic surface of the nanoelectrode promoted the one-electron reaction of H2O oxidation,leading to·OH concentrations that were 54.0 and 27.5 times higher,respectively,than those produced by Ti/Sb-SnO2,and 4.7 and 2.0 times higher,respectively,than those produced by TNT/Sb-SnO2-300.Moreover,intermediate products suggested the ring-opening of benzene and toluene,yielding easily degradable small organic molecules.The electrochemical oxidation(EO)process revealed a competitive relationship between benzene and toluene,with toluene exhibiting stronger competitive effects(kinetic constant was 2.1 times that of benzene).The efficient nanoelectrode provide a novel approach for the removal of benzene and toluene from aquatic environments through EO.
查看更多>>摘要：Infrared thermography technology is a noninvasiveness and real-time imaging method,it has attracted enormous attentions for blood flow imaging.However,the implementation of infrared thermography technology is still limited by the poor imaging quality caused by the low temperature discrimination between the target blood vessel and background.Herein,we reported a flexible and low-cost MXene based photothermal microheater for enhancing the infrared imaging of blood flow.In the experiment,MXene films with specific thickness was pre-pared by vacuum filtering different concentrations of MXene colloidal solutions.Thereafter,the microheaters were fabricated by assembling the MXene films on the PU tape/PDMS substrate,and then sealed with another layer of pure PDMS film on the top of MXene film.The photothermal performance of the microheaters were evaluated by using an 808-nm laser as the exciting source.Experimental results show that the optimal micro-heater(MXene content:17.5 mg)can reach a safe temperature of 41.5 ℃ with 43.9 s under the light irradiation of 100 mW·cm-2.Moreover,it can be stabilized at the equilibrium temperate for over 25 min.Finally,the above optimal microheater was used to accurately heat the simulated blood vessel.It shows that temperature difference of 3.3 ℃ can be induced between the heated blood vessel and environment.As a result,it significantly enhances the quality of the infrared imaging of the blood flow in the simulated vascular network.
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