查看更多>>摘要：The application of metal-organic frameworks(MOFs)is hindered by several crucial factors,including low photocatalytic efficiency,poor stability and challenges in recycling.In this study,MIL-53(Fe)was grown in situ on a charcoal sponge(CS)with a large surface area,excellent mechanical properties,and high photocatalytic efficiency using a solvothermal method,thus addressing the above-mentioned shortcomings of MOF materials.Notably,CS/MIL-53(Fe)has an amazing light-harvesting capacity in the visible range,leading to a significant improvement in the utilization of light.The results of the experiments indicate that CS/MIL-53(Fe)displays a higher photocatalytic activity(87％Cr(Ⅵ))when exposed to visible light than CS(58％)or MIL-53(Fe)(27％),attributing to the increased separation of photogenerated carriers.e-is the main reactive radical and dominates the photocatalytic reduction process,rooting from that e-can reduce Cr(Ⅵ)to low-toxicity Cr(Ⅲ).This study presents a novel method for constructing photocatalysts with large surface areas,superior mechanical characteristics,and enhanced photocatalytic performance.Additionally,it achieves the resource utilization of agricultural and forestry waste.
查看更多>>摘要：Magnesium-based hydrides have been widely recognized as an appropriate choice for solid-state hydro-gen storage.However,its undesirable thermodynamics and sluggish hydrogenation/dehydrogenation kinetics are major bottlenecks for its application.Herein,a highly stable and highly dispersed Ni-based catalyst(Ni/Al2O3/GN)was fabricated to promote the hydrogen storage performance of MgH2 via the electrostatic effect of NiAl-LDH/GN pre-cursor with a co-calcination reduction process.MgH2-5 wt％Ni/Al2O3/GN exhibits excellent hydrogen storage performance,releasing about 5.7 wt％hydrogen in 3500 s at 250 ℃,and can reach a saturation hydrogen absorption of about 6.15 wt％in 3000 s at 100 ℃.Furthermore,it also shows low dehydrogenation apparent activation energy of 89.1 and 118.2 kJ·mol-1.Impressively,the catalyst ensures the stability of both the physical phase and structure during ball milling and cycling process.The role of each phase in Ni/Al2O3/GN on the hydrogen storage performance of MgH2 was also discussed through experiments and theo-retical calculation,and the synergistic catalytic mechanism of Ni/Al2O3/GN was clearly elaborated.This work pro-vides a unique perspective for the preparation of highly stable and highly dispersible catalysts.
查看更多>>摘要：2LiBH4-MgH2 composite is one of the most attractive reactive hydride composites with a theoretic hydrogen capacity of 10.8 wt％.However,the large nucleation restriction of MgB2 during the second step of dehydrogenation results in sluggish hydrogen storage kinetics and high operating temperature,which hinders its practical application as on-board hydrogen storage mate-rials.Herein,Al3Ti doped Al nanoparticles(AT NPs)are prepared by a facile chemical reduction reaction to improve the hydrogen storage performance of 2LiBH4-MgH2 composite.During the initial H2 desorption process,MgAlB4 and TiB2 that have identical crystal structure and low d-value mismatch with MgB2 resulting from the reaction between AT NPs and 2LiBH4-MgH2 composite serve as effective nucleation sites for the formation of MgB2.As a result,the apparent activation energy of the two-step H2 desorption of AT NPs doped 2LiBH4-MgH2 composite are notably decreased to(110.0±5.9)and(119.6±1.4)kJ·mol-1,which is 55.5 and 33.5 kJ.mol-1 lower than that of the undoped sample.More importantly,a reversible hydrogen storage capacity of 9.2 wt％after 10 cycles of H2 desorption and adsorption could be achieved,corresponding to a capacity retention rate of 99％.The building of reactive bimetallic catalyst towards in situ formation of heterogeneous nucleation sites provides a new strategy for improving the hydrogen storage performance of reactive hydride composites.
查看更多>>摘要：The heterointerface engineering involving dif-ferent components or phases represents a desirable strategy for enhancing the sluggish kinetics of hydrogen evolution reaction(HER).However,constructing desired heteroint-erfaces and elucidating the reaction mechanisms on the interface remains a considerable challenge.In this work,we propose a straightforward electrochemical synthesis strategy to prepare the nickel sulfide-based heterointerfaces for HER.The mechanism of electrochemical synthesis is revealed,wherein metal-thiourea species can be formed at the cathode potential and subsequently oxidized to nickel sulfides at the anode potentials.Leveraging this mechanism,a range of nickel sulfides,including NiS,Ni3S2/NiS,Ni/Ni3S2 and Ni3S2,have been successfully synthesized by tuning the potential range of cyclic voltammetry.Among these,the obtained Ni3S2/NiS@CC(CC:carbon cloth)exhibits the smallest overpotential of 84 mV at 10 mA·cm-2 and high stability.Theoretical calculations further reveal that the combination of NiS and Ni3S2 induces electron redistribution at the interface,and thus the Volmer process is effectively promoted with faster water dissociation and OH desorption kinetics.Signifi-cantly,the simplicity method coupled with a clear syn-thesis mechanism and outstanding HER performance highlights its promising potential for practical applications.
查看更多>>摘要：The facile construction of nanoscale NbHx supported by Ti3C2(NbHx@Ti3C2)was achieved using facile ball milling strategy to improve the hydrogen des-orption kinetics and reversibility of magnesium borohy-dride(Mg(BH4)2).The doping of 30 wt％NbHx@Ti3C2 catalyst reduced the onset dehydrogenation temperature of Mg(BH4)2 to 71.2 ℃.Additionally,the Mg(BH4)2+30 NbHx@Ti3C2 composite achieved remarkable hydrogen release of over 9.2 wt％at a temperature as low as 230 ℃,indicating unexpected dehydrogenation kinetics.Moreover,the reversibility of NbHx@Ti3C2 doped Mg(BH4)2 was retained to more than 4.2 wt％after four cycles,which was increased by 68％compared to that of undoped Mg(BH4)2.The strong catalysis of NbHx@Ti3C2 catalyst could be attributed to the synergistic effect of NbHx and Ti3C2 in hydrogen spillover and diffusion.NbHx acted as a"hydrogen pump"for effective hydrogen spillover,while Ti3C2 created numerous diffusion channels for hydrogen dissolution and provided the active catalytic site to facili-tate the re/dehydrogenation of Mg(BH4)2.
查看更多>>摘要：The identification of indoor harmful gases is imperative due to their significant threats to human health and safety.To achieve accurate identification,an effective strategy of constructing a sensor array combined with the pattern recognition algorithm is employed.Carbon-based thin-film transistors are selected as the sensor array unit,with semiconductor carbon nanotubes(CNTs)within the TFT channels modified with different metals(Au,Cu and Ti)for selective responses to NH3,H2S and HCHO,respectively.For accurate gas species identification,an identification mode that combines linear discriminant analysis algorithms and logistic regression classifier is developed.The test results demonstrate that by preprocessing the sensor array's sensing data with the LDA algorithm and subsequently employing the LR classifier for identification,a 100％recognition rate can be achieved for three target gases(NH3,H2S and HCHO).This work provides significant guidance for future applications of chip-level gas sensors in the realms of the Internet of Things and Artificial Intelligence.
查看更多>>摘要：Exploring the structure-activity relationship between the performance of gas sensors and the structure of semiconductor metal oxide(SMO)nanomaterials is crucial for understanding and designing gas-sensing materials and overcoming the application limitations of SMO-based gas sensors.Regulation of a single SMO microstructure provides a promising solution to address this scientific problem due to its controllable composition.In this study,we control the grain boundary(GB)density of Fe2O3 nanomaterials using a simple solvothermal method.They have similar chemical compositions and crystal phases,providing an ideal platform for studying the influence of the GB density on the gas-sensing perfor-mance.Gas-sensing tests showed that the Fe2O3-1 sensor with medium GB density and the Fe2O3-2 sensor with high GB density had higher sensitivity and selectivity than the Fe2O3-0 sensors with low GB density before reaching the optimal operating temperature.However,when the GB density increased,the response to acetone decreased slightly,whereas the optimal operating temperature decreased.This work highlights the unique performance of the GB density in enhancing the gas sensitivity of a single SMO.
查看更多>>摘要：Indium selenide(InSe),as a wide-bandgap semiconductor,has received extensive attention in the flexible electronics field in recent years due to its excep-tional plasticity and promising thermoelectric performance.However,the low carrier concentration severely limits its thermoelectric performance improvement.In this work,we conducted contrasting strategies that can be employed to increase the carrier concentration of InSe,including bandgap narrowing and heterovalent doping.Specifically,the carrier concentration initially increases as a result of the reduced bandgap upon Te alloying and then slightly decreases due to the weak electronegativity of Te.Whereas Br doping realizes high carrier concentration by pushing the Fermi level into the conduction bands and activating the multiple bands.On the other hand,both Te and Br obviously suppress the thermal conductivity due to the point defect scattering.By contrast,Br doping realizes a higher thermoelectric performance with a maximum ZT of～0.13 at 773 K benefiting from the better optimization of carrier concentration.This work elucidates the strategies for enhancing carrier concentration at anion sites and demonstrates the high efficiency of halogen doping in InSe.Moreover,the carrier concentration of InSe is promising to be further optimized,and future work should focus on employing approaches such as cation doping or second-phase compositing.
查看更多>>摘要：With the continuous exploration of uncharted and extreme environments,enhanced temperature robust-ness of passive devices has become particularly important.In this study,a ceramic-based meta-material absorber with exceptional temperature stability is developed using a fusion design approach that combines rare metal-based tungsten bronze structural ceramics and meta-materials.Specifically,the absorbance of the meta-material array based on Mie resonance exceeds 49.0％in both waveguides and free space,approaching the theoretical limit.Accord-ing to impedance analysis,the absorption performance can be distinctly correlated with the dielectric loss(Qf).Nota-bly,the high-temperature robustness is verified to still be effective at 400 ℃.These advancements in our design allow for the use of monolithic materials in fabricating temperature-stable perfect absorbers,providing greater freedom in the dielectric performance and expanding their potential applications,including in space exploration and 5G millimeter-wave scenarios.
查看更多>>摘要：Heat treatment significantly influences homo-geneous material microstructures and mechanical proper-ties,which can be improved by an optimal heat treatment process.However,heat treatment application to heteroge-neous materials presents significant challenges due to compositional and microstructural heterogeneities.Herein,a laminated heterostructured alloy comprising alternating 316L stainless steel(SS)and 18Ni300 maraging steel(MS)layers fabricated using wire and arc additive manufacturing was investigated.A solution treatment was applied at 900 ℃ for 0.5 h.Subsequently,the solution-treated and as-fabricated(AF)samples were aged at 500 ℃ for 4 h;these samples were denoted SA and AT,respectively.The AT phase compositions and orientations were similar to those of AF.The SA 316L SS layer resembled that of AF,but the SA 18Ni300 MS layers exhibited a reduced austenite phase fraction and refined grain size,attributable to solid-state transformation.In the AT sample,aging induced the for-mation of nanoscale acicular ω phase and ellipsoidal Ni3Ti,Fe2Mo,and X precipitates in the 18Ni300 MS layers.Conversely,the SA precipitates contained acicular FeNi2 and ellipsoidal ω,Ni3Ti,and X precipitates,and their fractions were lower than those in AT precipitates.The 18Ni300 MS layer microhardness in the heat-treated sam-ples increased due to nanoprecipitation,but the 316L SS layer microhardness resembled that of AF.The AT and SA ultimate tensile strengths increased to(1360±50)and(1473±41)MPa,respectively,attributable to precipita-tion strengthening.The SA 316L SS layer exhibited a high stress-induced martensite fraction,enhancing the ductility of heated samples.
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