TiB_(2)coatings can significantly enhance the high-temperature oxidation resistance of molybdenum,which would broaden the application range of molybdenum and alloys thereof.However,traditional methods for preparing Ti...TiB_(2)coatings can significantly enhance the high-temperature oxidation resistance of molybdenum,which would broaden the application range of molybdenum and alloys thereof.However,traditional methods for preparing TiB_(2)coatings have disadvantages such as high equipment costs,complicated processes,and highly toxic gas emissions.This paper proposes an environmentally friendly method,which requires inexpensive equipment and simple processing,for preparing TiB_(2)coating on molybdenum via electrophoretic deposition within Na3AlF6-based molten salts.The produced TiB_(2)layer had an approximate thickness of 60μm and exhibited high density,outstanding hardness(38.2 GPa)and robust adhesion strength(51 N).Additionally,high-temperature oxidation experiments revealed that,at900℃,the TiB_(2)coating provided effective protection to the molybdenum substrate against oxidation for 3 h.This result indicates that the TiB_(2)coating prepared on molybdenum using molten salt electrophoretic deposition possesses good high-temperature oxidation resistance.展开更多
The problem of water and sulfur poisoning in flue gas atmosphere remains a significant obstacle for low-temperature deNO_(x) catalysts.This study investigated the sulfation mechanism of the CoMn_(2)O_(4)/CeTiO_(x)(CMC...The problem of water and sulfur poisoning in flue gas atmosphere remains a significant obstacle for low-temperature deNO_(x) catalysts.This study investigated the sulfation mechanism of the CoMn_(2)O_(4)/CeTiO_(x)(CMCT)catalyst during the selective catalytic reduction of NO_(x) with NH3 under conditions containing H2O and SO_(2) at 150℃.Employing a comprehensive suite of time-resolved analysis and characterization techniques,the evolution of sulfate species was systematically categorized into three stages:initial rapid surface sulfate accumulation,the transformation of surface sulfates to bulk metal sulfates,and partial sulfates decomposition after the removal of H2O and SO_(2).These findings indicate that bulk metal sulfates irreversibly deactivate the catalyst by distorting active component lattices and consuming oxygen vacancies,whereas surface sulfates(including ammonium sulfates and surface-coordinated metal sulfates)cause reversible performance loss through decomposition.Furthermore,the competitive adsorption of H2O and SO_(2) significantly influences the catalytic efficiency,with H2O suppressing SO_(2) adsorption while simultaneously enhancing the formation of Brönsted acid sites.This research underscores the critical role of sulfate dynamics on catalyst performance,revealing the enhanced SO_(2) resistance of the Eley-Rideal mechanism facilitated by the Ce-Ti support relative to the Langmuir-Hinshelwood pathway.Collectively,the study unravels the complex interplay of sulfate dynamics influencing catalyst performance and provides potential approaches to mitigate deactivation in demanding atmospheric conditions.展开更多
Mixed polyanion phosphate Na_(4)Fe_(3)(PO_(4))_(2)P_(2)O_(7)(NFPP)is regarded as the most promising cathode material for sodium-ion batteries(SIBs),due to its high structural stability and low-cost environmental frien...Mixed polyanion phosphate Na_(4)Fe_(3)(PO_(4))_(2)P_(2)O_(7)(NFPP)is regarded as the most promising cathode material for sodium-ion batteries(SIBs),due to its high structural stability and low-cost environmental friendliness.However,its intrinsic low conductivity and sluggish Na^(+)diffusion restricted the fast-charge and low-temperature sodium storage.Herein,an NFPP composite encapsulated by in-situ pyrolytic carbon and coupled with expanded graphite(NFPP@C/EG)was constructed via a sol-gel method followed by a ballmill procedure.Due to the dual-carbon modified strategy,this NFPP@C/EG only enhanced the electronic conductivity,but also endowed more channels for Na^(+)diffusion.As cathode for SIBs,the optimized NFPP(M-NFPP@C/EG)delivers excellent rate capability(capacity of~80.5 mAh/g at 50 C)and outstanding cycling stability(11000 cycles at 50 C with capacity retention of 89.85%).Additionally,cyclic voltammetry(CV)confirmed that its sodium storage behavior is pseudocapacitance-controlled,with in-situ electrochemical impedance spectroscopy(EIS)further elucidating improvements in electrode reaction kinetics.At lower temperatures(0℃),M-NFPP@C/EG demonstrated exceptional cycling performance(8800 cycles at 10 C with capacity retention of 95.81%).Moreover,pouch cells also exhibited excellent stability.This research demonstrates the feasibility of a dual carbon modification strategy in enhancing NFPP and proposes a low-cost,high-rate,and ultra-stable cathode material for SIBs.展开更多
The utilization of phosphors that achieve full-spectrum lighting has emerged as a prevailing trend in the advancement of white light-emitting diode(WLED)lighting.In this study,we successfully prepared a novel green ph...The utilization of phosphors that achieve full-spectrum lighting has emerged as a prevailing trend in the advancement of white light-emitting diode(WLED)lighting.In this study,we successfully prepared a novel green phosphor Ba_(2)Sc_(2)((BO_(3))_(2)B_(2)O_(5)):Ce^(3+)(BSBO:Ce^(3+))that can be utilized for full-spectrum lighting and low-temperature sensors.BSBO:Ce^(3+)exhibits a broad-band excitation spectrum centered at 410 nm,and a broad-band emission spectrum centered at 525 nm.The internal and external quantum efficiencies of BSBO:Ce^(3+)are 99%and 49%,respectively.The thermal stability of BSBO:Ce^(3+)can be improved by substituting partial Sc atoms with smaller cations.The thermal quenching mechanism of BSBO:Ce^(3+)and the lattice occupancy of Ce ions in BSBO are discussed in detail.Furthermore,by combining the green phosphor BSBO:Ce^(3+),the commercial blue phosphor and the red phosphor on a 405 nm chip,a white light source was obtained with a high average color rendering index(CRI)of 96.6,a low correlated color temperature(CCT)of 3988 K,and a high luminous efficacy of 88.0 Im/W.The lu-minous efficacy of the WLED exhibits negligible degradation during the 1000 h light aging experiment.What's more,an emission peak at 468 nm appears when excited at 352 nm and 80 K,however,the relative intensity of the peaks at 468 and 525 nm gradually weakens with increasing temperature,indicating the potential of this material as a low-temperature sensor.展开更多
Compositing a secondary phase in Ag_(2)Se can usually tune the electron and phonon scattering to improve the thermoelectric performance.However,the intrinsically high carrier concentration still limits the performance...Compositing a secondary phase in Ag_(2)Se can usually tune the electron and phonon scattering to improve the thermoelectric performance.However,the intrinsically high carrier concentration still limits the performance optimization.Here,we employ a modulation decoration strategy to simultaneously achieve submicron-scale constituents and compositional modification for synergistic optimization of thermoelectric properties.Amorphous nano Sb_(2)S_(3) has been decorated on the surface of Ag_(2)Se powders,and S was added into the Ag_(2)Se matrix through an ion exchange reaction accompanied by the formation of a crystal/amorphous mixed secondary phase of Sb_(2)(S,Se)_(3).The S doping reduced the excessive intrinsic carrier concentration,leading to modified electrical transport properties and significantly reduced electrical thermal conductivity.On the other hand,introducing the S dopants and the crystal/amorphous interfaces into the Ag_(2)Se matrix could increase the lattice anharmonicity,further contributing to the reduced thermal conductivity.Consequently,the Ag_(2)Se-0.4%Sb_(2)S_(3) sample obtains a high average zT value of>1 in the temperature range of 300–390 K.In addition,the maximum cooling temperature difference of over 85 K can be predicted in an Ag_(2)Se/Ag_(2)Se-0.4%Sb_(2)S_(3) segregated module at the hot side temperature of 350 K.展开更多
The inkjet-printed Cu_(2)ZnSn(S,Se)_(4)(CZTSSe)has garnered extensive attention owing to its costeffectiveness,high-throughput fabrication,and roll-to-roll compatibility.However,selenium volatility loss during high-te...The inkjet-printed Cu_(2)ZnSn(S,Se)_(4)(CZTSSe)has garnered extensive attention owing to its costeffectiveness,high-throughput fabrication,and roll-to-roll compatibility.However,selenium volatility loss during high-temperature selenization induces detrimental defects in both bulk and interface,limiting CZTSSe solar cell performance.Here,we develop a simple and controllable low-temperature selenium post-treatment(Se-LPT)strategy to compensate for the selenium loss.Systematic studies reveal that the Se-LPT can effectively passivate selenium vacancy deep-level defects in the CZTSSe absorber and suppresses carrier nonradiative recombination,thereby reducing the open-circuit voltage deficit from 336to 298 mV.Furthermore,this treatment lowers the carrier transport barrier and facilitates efficient carrier transport by reducing the spike-like conduction band offset at the heterojunction interface.The enhanced carrier density and conductivity further contribute to the short-circuit current improvement.Consequently,the Se-LPT CZTSSe devices deliver an efficiency of 14.13%,representing the highest performance reported to date for inkjet-printed CZTSSe solar cells.This work demonstrates an effective route for developing cost-effective and high-efficiency CZTSSe photovoltaics.展开更多
To improve the thermal insulation performance of SiO_(2)aerogels at high temperatures,SiO_(2)precursor solutions were prepared via a sol-gel two-step method.Fe_(2)O_(3)powder was extra added as an opacifier to the SiO...To improve the thermal insulation performance of SiO_(2)aerogels at high temperatures,SiO_(2)precursor solutions were prepared via a sol-gel two-step method.Fe_(2)O_(3)powder was extra added as an opacifier to the SiO_(2)precursor solutions with mass fractions of 0,0.2%,0.5%,1.0%,and 3.0%;and Fe_(2)O_(3)-SiO_(2)composite aerogels were fabricated using CO_(2)supercritical drying technology.The effects of the Fe_(2)O_(3)extra addition on the aerogels were investigated.The results show that:(1)Fe_(2)O_(3)doping does not alter the aerogel morphology;Fe_(2)O_(3)suppresses the mass loss at high temperatures and enhances the high-temperature stability of the composite;(2)below 800℃,the aerogel with 0.5%Fe_(2)O_(3)exhibits the lowest thermal conductivity and the best thermal insulation performance;at 800-1000℃,the aerogel with 1%Fe_(2)O_(3)exhibits the lowest thermal conductivity and a good nanoporous structure;(3)by adjusting the Fe_(2)O_(3)extra addition,composite aerogels suitable for different temperature ranges can be tailored.展开更多
Two different Mn-Ce-O_(x)/TiO_(2) catalysts were prepared by ordinary impregnation(denoted as MCT) and citric acid assisted impregnation(denoted as MCT-CA) methods,respectively.Excellent NOxremoval is achieved over MC...Two different Mn-Ce-O_(x)/TiO_(2) catalysts were prepared by ordinary impregnation(denoted as MCT) and citric acid assisted impregnation(denoted as MCT-CA) methods,respectively.Excellent NOxremoval is achieved over MCT-CA for selective catalytic reduction with NH3(NH_(3)-SCR),and 100% NOxconversion is obtained at 125℃ under weight hour space velocity(WHSV) of 80000 mL/(gcat·h).Particularly,100% NOxis converted on MCT-CA in the presence of 10 vol% H2O at 175℃.As H2O and SO2coexist in the reaction system for 9 h,NO_(x) conversion can still be maintained>90%,much higher than that(22%) of MCT.A series of characterization results indicates that MCT-CA exhibits a larger BET specific surface area,pore volume,and pore size,which enhances the dispersion of Mn and Ce oxides and promotes the rapid adsorption of reactants and desorption of products.Additionally,MCT-CA possesses more Mn^(4+),Ce^(3+),chemisorbed oxygen species,and stronger reducibility,facilitating the co nversion of NO to NO_(2).Specially,the amount of active NH_(3) species and active nitrate species on MCT-CA is much more than that over MCT,The combined effect of the aforementioned factors devotes to the excellent low-temperature SCR performance and tolerance to H2O/SO2over MCT-CA.展开更多
In recent years,modification of texture distribution has been considered a valid approach to improve the room-temperature(RT)formability of magnesium(Mg)alloys.In this study,a novel Mgsingle bond2Znsingle bond3Lisingl...In recent years,modification of texture distribution has been considered a valid approach to improve the room-temperature(RT)formability of magnesium(Mg)alloys.In this study,a novel Mgsingle bond2Znsingle bond3Lisingle bond1Gd alloy sheet with weak elliptical-texture was fabricated by cold rolling and subsequent annealing,and it showed an excellent Erichsen(IE)value near 7.1 mm.Both quasi-in-situ electron backscatter diffraction(EBSD)and transmission electron microscopy(TEM)analysis indicate that considerable basal and pyramidal dislocations can be activated in the cold rolling process.During annealing,these dislocations can induce nucleation and then cause preferential misorientation relationships around〈uvt0〉concerning the nuclei and parent grains,which can facilitate the formation of elliptical texture.Furthermore,the particle-stimulated nucleation(PSN)mechanism and the co-segregation of Zn and Gd at grain boundaries(GB)further weak texture intensity.Finally,the mechanical properties of the Mgsingle bond2Znsingle bond3Lisingle bond1Gd alloy sheet are significantly improved.展开更多
Efficient,safe,and reliable energy output from high-energy-density lithium metal batteries(LMBs)at all climates is crucial for portable electronic devices operating in complex environments.The performance of correspon...Efficient,safe,and reliable energy output from high-energy-density lithium metal batteries(LMBs)at all climates is crucial for portable electronic devices operating in complex environments.The performance of corresponding cathodes and lithium(Li)metal anodes,however,faces significant challenges under such demanding conditions.Herein,a nonflammable electrolyte for high-voltage Li‖LCO cells has been designed,including partially-fluorinated ethyl 4,4,4-trifluorobutyrate(ETFB)as the key solvent,guided by theoretical calculations.With this ETFB-based electrolyte,Li‖LCO cells exhibit enhanced reversible capacities and superior capacity retention at an elevated charge voltage of 4.5 V and a wide operating temperature range spanning from-60℃to 70℃.The cells achieve 67.1%discharge capacity at-60℃,relative to room temperature capacity,and 85.9%100th-cycle retention at 70℃.The outstanding properties are attributed to the LiF-rich interphases formed in the ETFB-based electrolyte with a finetuned solvation structure,in which the coordination environment in the vicinity of Li^(+)cations and the distance between anion and solvents are subtly adjusted by introducing ETFB.This solvation structure has been mutually elucidated through joint spectra characterizations and atomistic simulations.This work presents a new strategy for the design of electrolytes to achieve all-climate reliable and safe application of LMBs.展开更多
Constructing high-performance electrocatalysts for oxygen evolution reaction(OER) using a simple and economical strategy is considerably meaningful yet still challenging. Herein, Co(OH)_(2)/Mo_(2)Ti C_(2)T_(x)(where T...Constructing high-performance electrocatalysts for oxygen evolution reaction(OER) using a simple and economical strategy is considerably meaningful yet still challenging. Herein, Co(OH)_(2)/Mo_(2)Ti C_(2)T_(x)(where Txrepresents the surface functional groups,-O,-OH and-F) hetero-nanosheets were facilely prepared by the in situ topochemical transformation at room temperature towards efficient OER. The integrity of Co(OH)_(2)nanosheets and Mo_(2)Ti C_(2)T_(x) nanosheets affords interfacial coupling to optimize the electronic structures of Co and Mo ions, which endows the high electron transfer efficiency and rapid reaction kinetics. As a result, the Co(OH)_(2)/Mo_(2)Ti C_(2)T_(x) hetero-nanosheets exhibit excellent OER performances with low overpotentials of 283 m V on glass-carbon electrode, and 227 m V on nickel foam at 10 m A/cm^(2). Furthermore, the decent anti-alkali ability underpins superior operational stability exceeding 100 h, demonstrating grand potential in practical applications. This work provides a new insight for the synthesis of efficient and cost-effective two-dimensional(2D) material-based electrocatalysts.展开更多
Catalytic regeneration is a key approach to solving high energy consumption issues in the amine-based CO_(2)absorption method.Previous studies have shown that loaded acid sites(such as SO_(4)^(2-))are beneficial for p...Catalytic regeneration is a key approach to solving high energy consumption issues in the amine-based CO_(2)absorption method.Previous studies have shown that loaded acid sites(such as SO_(4)^(2-))are beneficial for promoting low-temperature CO_(2)-rich amine regeneration,but their weak binding strength to the support results in limited catalyst life.Herein,we proposed an advanced catalyst modification strategy to maintain the active hydroxyl group(Zr-OH-Fe)via actively transferring electrons on the surface of FeZrO_(x)nano-heterojunction.Combining in situ DRIFTS and DFT calculations,we revealed that the ZrOH-Fe at the ZrO_(2)-Fe_(2)O_(3)heterointerfaces exhibit enhanced proton-donating ability,with deprotonation energy reduced from 2.94 to 2.61 eV compared to Zr-OH(which should be called inert hydroxyl group).This improvement favors the rate-determining proton transfer step from RNH_(3)^(+)to RNHCOO^(-).Surprisingly,it increased the CO_(2)desorption rate by 10.5 times and reduced the energy consumption by 43.6%during amine regeneration.This work offers a practical strategy for improving the performance of lowtemperature CO_(2)-rich amine regeneration catalysts,and the low-cost recyclability of amine used in CO_(2)capture.展开更多
Thorium dioxide(ThO_(2))fibers exhibit exceptional structural stability,low density and superior flexibility,coupled with a remarkably high melting point,positioning them as promising candidates for thermal protection...Thorium dioxide(ThO_(2))fibers exhibit exceptional structural stability,low density and superior flexibility,coupled with a remarkably high melting point,positioning them as promising candidates for thermal protection applications.Additionally,their commendable secondary processing characteristics enable the development of diverse composite materials when integrated with other materials,significantly broadening the potential utilization of ThO_(2)materials and thorium resources in industrial fields.In this work,the ThO_(2)fiber was fabricated by the sol-gel precursor method,and the precursor with good spinnability and excellent stability was synthesized for the first time.The ThO_(2)fiber with a mean diameter of 868 nm is both highly flexible and strong(max.tensile strength 2.21 MPa),capable of bending freely across a wide temperature range from-196℃(in liquid nitrogen)to 1200℃.Meanwhile,it exhibits excellent temperature stability and heat insulation properties.The ThO_(2)nanofiber membranes with layered structure have low density(32-37 mg·cm^(-3)),low thermal conductivity(27.3-30.1 mW·m^(-1)·K^(-1)@25℃).The ThO_(2)nanofiber membranes with 15 mm thickness can reduce the temperature from 1200 to 282℃and maintain a high aspect ratio and bendability after 1200℃@90 min.The results show that the ThO_(2)fiber can be used as a new kind of high-temperature resistant material.展开更多
Uniaxial tensile testing explored the Portevin-Le Chatelier(PLC)effect in nickel-based superalloys featuring high Mo/Cr mass ratios,focusing on the influence of variations in the initial microstructure on the deformat...Uniaxial tensile testing explored the Portevin-Le Chatelier(PLC)effect in nickel-based superalloys featuring high Mo/Cr mass ratios,focusing on the influence of variations in the initial microstructure on the deformation behavior at room and elevated temperatures.Experimental results indicated that the PLC effect was observed solely in the high-temperature tensile curves.However,the deformation mechanisms and characteristics of the PLC effect varied with different initial microstructures.Solid solution(SS)and over-aged(OA)samples exhibited C-type serrations,while under-aged(UA)and peak-aged(PA)specimens,featuring short-and long-range ordered phases,respectively,exhibited A+B type serrations in their tensile curves.Microstructural evolution from the SS to the UA,PA and OA states changed their stacking fault energy(SFE),leading to a sequential transformation in the plastic deformation mechanisms during high-temperature tensile deformation:stacking fault(SF)→nanotwin→microtwin→SF.C-type serrations in the SS samples were associated with high solute-atom contents and SF formation.The PLC effects in the UA and PA samples were predominantly caused by solute atom pinning dislocations.Although precipitates and twins were not the primary drivers of the PLC effect,they impeded dislocation migration,exacerbated solute-atom segregation and enhanced dislocation pinning,generating A+B-shaped serrations.In the OA specimens,precipitated phases induced interfacial mismatch under thermal-force coupling.SF shearing of the precipitated phase and subsequent re-dissolution facilitated the formation of C-type serrations,whose PLC effect was induced by the combined action of dynamic strain aging(DSA),SFs of the matrix and diffusion-controlled pseudo-locking mechanisms.展开更多
The development of efficient low-load platinum catalysts for CO oxidation is critical for large-scale industrial applications and environmental protection.In this study,a strategy of N_(2)treatment triggered the self-...The development of efficient low-load platinum catalysts for CO oxidation is critical for large-scale industrial applications and environmental protection.In this study,a strategy of N_(2)treatment triggered the self-reforming into fully exposed Pt cluster catalysts was proposed.By adjusting the coordination environment of Pt species on the defect support through N_(2)treatment,the CO catalytic activity was significantly enhanced,achieving complete CO oxidation at 130℃with a Pt loading of only 0.1 wt.%.The turnover frequency of N_(2)-treated Pt_(FEC)/Ti-D at 160℃was 18.3 times that of untreated Pt_(SA)/Ti-D.Comprehensive characterization results indicated that the N_(2)treatment of the Pt single-atom defect catalyst facilitated the reconfiguration and evolution of the defect structure,leading to the aggregation of Pt single atoms into fully exposed Pt clusters.Notably,these fully exposed Pt clusters exhibited a reduced coordination of Pt–O in the first coordination shell compared to single atoms,which resulted in the formation of Pt–Pt metal coordination.This unique coordination structure enhanced the adsorption and activation of CO and O_(2)on the catalyst,thereby resulting in exceptionally low-temperature CO oxidation activity.This work demonstrates a promising strategy for the design,synthesis,and industrial application of efficient low-platinum load catalysts.展开更多
An Al_(2)O_(3)/Al-Cu-Mn composite was fabricated using a combination of ball milling and liquid-solid reaction,with a nominal composition of Al-4Cu-0.5Mn-2.8γ-Al_(2)O_(3).The composite contains reinforcement particle...An Al_(2)O_(3)/Al-Cu-Mn composite was fabricated using a combination of ball milling and liquid-solid reaction,with a nominal composition of Al-4Cu-0.5Mn-2.8γ-Al_(2)O_(3).The composite contains reinforcement particles,including nano-sizedθ’and T(Al_(20)Cu_(2)Mn_(3))particles after T6 heat treatment,as well as in-situ synthesized nano-sizedγ-Al_(2)O_(3)particles.Tensile tests of the Al-4Cu-0.5Mn-2.8γ-Al_(2)O_(3)composite and the Al-4Cu-0.5Mn base alloy after T6 treatment were carried out at room temperature and elevated temperatures(200°C,300°C,and 400°C).Compared with the base alloy,the yield strength of the Al-4Cu-0.5Mn-2.8γ-Al_(2)O_(3)composite after T6 treatment increases significantly from 187 MPa to 263 MPa at room temperature.Simultaneously,at elevated temperatures,the yield strength is also enhanced,with a yield strength of 52 MPa at 400°C for this composite.The in-situ fabricatedγ-Al_(2)O_(3)particles,mainly distributed along the grain boundaries,are supposed to play the main strengthening role,especially at high temperatures.This work acts as a reference for designing composites for high-temperature applications.展开更多
The fracture behavior at high temperatures of the Ti−22Al−26Nb alloy,which features duplex lamellar,bimodal,and Widmanstätten structures,was studied.Samples of the alloy were prepared through compression deformat...The fracture behavior at high temperatures of the Ti−22Al−26Nb alloy,which features duplex lamellar,bimodal,and Widmanstätten structures,was studied.Samples of the alloy were prepared through compression deformation in the trans-phase region followed by subsequent heat treatment.The results indicate that at 650℃,the fracture toughness of the Ti−22Al−26Nb alloy is increased by 41.7%compared to that with original microstructures.The content of the B2 phase significantly influences the inherent fracture toughness of the material,while the morphology and distribution of the precipitated phases primarily affect the tortuosity of the crack propagation path.Among the microstructural features,the morphology and geometric orientation of the lamellae most significantly impact the crack path;consequently,the Widmanstätten structure exhibits the most tortuous fracture path.Additionally,a predictive model for fracture toughness is developed,which effectively predicts the fracture toughness of Ti−22Al−26Nb alloys with various microstructures at 650℃.展开更多
Formaldehyde(HCHO)is a significant indoor pollutant found in various sources and poses potential health risks to humans.Noble metal catalysts show efficient and stable catalytic activity for ambient-temperature HCHO o...Formaldehyde(HCHO)is a significant indoor pollutant found in various sources and poses potential health risks to humans.Noble metal catalysts show efficient and stable catalytic activity for ambient-temperature HCHO oxidation,yet suffer from low metal utilization.Efforts focus on designing catalysts with enhanced intrinsic activity and reduced noble metal loading.In this study,we developed a simple pretreatment method using ammonia solution on SiO_(2)carrier to enhance the activity of the Pd/SiO_(2)catalyst for HCHO oxidation.After the carrier was pretreated with an ammonia solution,a significant promoting effect was observed on the Pd/SiO_(2)(NH_(3)·H_(2)O)-R catalyst.It achieved almost complete oxidation of 150 ppmV of HCHO at 25℃,much better than the Pd/SiO_(2)-R(5%HCHO conversion rate).Multiple characterization results indicated that the ammonia solution pretreatment of the SiO_(2)carrier increased the surface defects,facilitating the anchoring of Pd nanoparticles and increasing their dispersion.The increase dispersion of Pd resulted in the generation of additional oxygen vacancies on the catalyst surfaces.The increased in oxygen vacancies on the catalyst was beneficial for enhancing the catalyst's ability to activate H_(2)O to form surface hydroxyl groups,thereby accelerating the catalytic oxidation process of HCHO.The reaction mechanism of HCHO on the Pd/SiO_(2)(NH_(3)·H_(2)O)-R catalyst mainly follows an efficient pathway:firstly,the HCHO being oxidized by surface active hydroxyl groups to formate;subsequently,the formate being oxidized by hydroxyl groups to H_(2)O and CO_(2).This study provides a promising strategy for designing high-performance noble metal catalysts for HCHO catalytic oxidation.展开更多
Developing a high-efficiency catalyst with both superior low-temperature activity and good N_(2)selectivity is still challenging for the NH_(3)selective catalytic reduction(SCR)of NO_(x)from mobile sources.Herein,we d...Developing a high-efficiency catalyst with both superior low-temperature activity and good N_(2)selectivity is still challenging for the NH_(3)selective catalytic reduction(SCR)of NO_(x)from mobile sources.Herein,we demonstrate the improved low-temperature activity and N_(2)selectivity by regulating the redox and acidic properties of MnCe oxides supported on etched ZSM-5 supports.The etched ZSM-5 enables the highly dispersed state of MnCeOx species and strong interaction between Mn and Ce species,which promotes the reduction of CeO2,facilitates electron transfer from Mn to Ce,and generates more Mn^(4+)and Ce^(3+)species.The strong redox capacity contributes to forming the reactive nitrate species and-NH_(2)species from oxidative dehydrogenation of NH_(3).Moreover,the adsorbed NH_(3)and-NH_(2)species are the reactive intermediates that promote the formation of N_(2).This work demonstrates an effective strategy to enhance the low-temperature activity and N_(2)selectivity of SCR catalysts,contributing to the NO_(x)control for the low-temperature exhaust gas during the cold-start of diesel vehicles.展开更多
Sodium-ion batteries with ZnIn_(2)S_(4)(ZIS)anodes promise a high capacity and abundant resources.However,their inherent low conductivity,large volume expansion and sluggish Na+diffusion limit the development of the w...Sodium-ion batteries with ZnIn_(2)S_(4)(ZIS)anodes promise a high capacity and abundant resources.However,their inherent low conductivity,large volume expansion and sluggish Na+diffusion limit the development of the wide-temperature sodium storage.This study pioneers a scalable synthesis of hierarchical hollow structural ZIS/C heterostructure through in situ confined growth of ZIS nanosheets in porous hollow carbon spheres(PHCSs)via a hydrothermal method.This unique structure exhibits abundant heterostructures to facilitate charge transport,rich porous structures to promote electrolyte wettability,efficient space utilization to relieve volume expansion,as well as interconnected carbon networks to ensure framework stability.Consequently,ZIS/C exhibits exceptional cycling stability with 92%capacity retention after 1000 cycles.Notably,ZIS/C demonstrates good wide-temperature performance operating at–50∼90°C,especially,at–30°C with a capacity of 208 mA h g^(−1)at 0.3A g^(−1).The full cell of ZIS/C||Na_(3)V_(2)(PO_(4))_(3)exhibits excellent high-rate capability(178 mA h g^(−1)at 6A g^(−1)).展开更多
基金supported by the Original Exploratory Program of the National Natural Science Foundation of China(No.52450012)。
文摘TiB_(2)coatings can significantly enhance the high-temperature oxidation resistance of molybdenum,which would broaden the application range of molybdenum and alloys thereof.However,traditional methods for preparing TiB_(2)coatings have disadvantages such as high equipment costs,complicated processes,and highly toxic gas emissions.This paper proposes an environmentally friendly method,which requires inexpensive equipment and simple processing,for preparing TiB_(2)coating on molybdenum via electrophoretic deposition within Na3AlF6-based molten salts.The produced TiB_(2)layer had an approximate thickness of 60μm and exhibited high density,outstanding hardness(38.2 GPa)and robust adhesion strength(51 N).Additionally,high-temperature oxidation experiments revealed that,at900℃,the TiB_(2)coating provided effective protection to the molybdenum substrate against oxidation for 3 h.This result indicates that the TiB_(2)coating prepared on molybdenum using molten salt electrophoretic deposition possesses good high-temperature oxidation resistance.
文摘The problem of water and sulfur poisoning in flue gas atmosphere remains a significant obstacle for low-temperature deNO_(x) catalysts.This study investigated the sulfation mechanism of the CoMn_(2)O_(4)/CeTiO_(x)(CMCT)catalyst during the selective catalytic reduction of NO_(x) with NH3 under conditions containing H2O and SO_(2) at 150℃.Employing a comprehensive suite of time-resolved analysis and characterization techniques,the evolution of sulfate species was systematically categorized into three stages:initial rapid surface sulfate accumulation,the transformation of surface sulfates to bulk metal sulfates,and partial sulfates decomposition after the removal of H2O and SO_(2).These findings indicate that bulk metal sulfates irreversibly deactivate the catalyst by distorting active component lattices and consuming oxygen vacancies,whereas surface sulfates(including ammonium sulfates and surface-coordinated metal sulfates)cause reversible performance loss through decomposition.Furthermore,the competitive adsorption of H2O and SO_(2) significantly influences the catalytic efficiency,with H2O suppressing SO_(2) adsorption while simultaneously enhancing the formation of Brönsted acid sites.This research underscores the critical role of sulfate dynamics on catalyst performance,revealing the enhanced SO_(2) resistance of the Eley-Rideal mechanism facilitated by the Ce-Ti support relative to the Langmuir-Hinshelwood pathway.Collectively,the study unravels the complex interplay of sulfate dynamics influencing catalyst performance and provides potential approaches to mitigate deactivation in demanding atmospheric conditions.
基金supported by the National Key Research and Development Program of China(No.2022YFB2502000)the National Natural Science Foundation of China(Nos.U21A20332,51771076,U21A200970,52301266)the Science and Technology Planning Project of Guangzhou(No.2024A04J3332)。
文摘Mixed polyanion phosphate Na_(4)Fe_(3)(PO_(4))_(2)P_(2)O_(7)(NFPP)is regarded as the most promising cathode material for sodium-ion batteries(SIBs),due to its high structural stability and low-cost environmental friendliness.However,its intrinsic low conductivity and sluggish Na^(+)diffusion restricted the fast-charge and low-temperature sodium storage.Herein,an NFPP composite encapsulated by in-situ pyrolytic carbon and coupled with expanded graphite(NFPP@C/EG)was constructed via a sol-gel method followed by a ballmill procedure.Due to the dual-carbon modified strategy,this NFPP@C/EG only enhanced the electronic conductivity,but also endowed more channels for Na^(+)diffusion.As cathode for SIBs,the optimized NFPP(M-NFPP@C/EG)delivers excellent rate capability(capacity of~80.5 mAh/g at 50 C)and outstanding cycling stability(11000 cycles at 50 C with capacity retention of 89.85%).Additionally,cyclic voltammetry(CV)confirmed that its sodium storage behavior is pseudocapacitance-controlled,with in-situ electrochemical impedance spectroscopy(EIS)further elucidating improvements in electrode reaction kinetics.At lower temperatures(0℃),M-NFPP@C/EG demonstrated exceptional cycling performance(8800 cycles at 10 C with capacity retention of 95.81%).Moreover,pouch cells also exhibited excellent stability.This research demonstrates the feasibility of a dual carbon modification strategy in enhancing NFPP and proposes a low-cost,high-rate,and ultra-stable cathode material for SIBs.
基金the National Natural Science Foundation of China(22003035,21963006,22073061)the Project of Shaanxi Province Youth Science and Technology New Star(2023KJXX-076)the National Training Program of Innovation and Entrepreneurship for Undergraduates(202314390018)。
文摘The utilization of phosphors that achieve full-spectrum lighting has emerged as a prevailing trend in the advancement of white light-emitting diode(WLED)lighting.In this study,we successfully prepared a novel green phosphor Ba_(2)Sc_(2)((BO_(3))_(2)B_(2)O_(5)):Ce^(3+)(BSBO:Ce^(3+))that can be utilized for full-spectrum lighting and low-temperature sensors.BSBO:Ce^(3+)exhibits a broad-band excitation spectrum centered at 410 nm,and a broad-band emission spectrum centered at 525 nm.The internal and external quantum efficiencies of BSBO:Ce^(3+)are 99%and 49%,respectively.The thermal stability of BSBO:Ce^(3+)can be improved by substituting partial Sc atoms with smaller cations.The thermal quenching mechanism of BSBO:Ce^(3+)and the lattice occupancy of Ce ions in BSBO are discussed in detail.Furthermore,by combining the green phosphor BSBO:Ce^(3+),the commercial blue phosphor and the red phosphor on a 405 nm chip,a white light source was obtained with a high average color rendering index(CRI)of 96.6,a low correlated color temperature(CCT)of 3988 K,and a high luminous efficacy of 88.0 Im/W.The lu-minous efficacy of the WLED exhibits negligible degradation during the 1000 h light aging experiment.What's more,an emission peak at 468 nm appears when excited at 352 nm and 80 K,however,the relative intensity of the peaks at 468 and 525 nm gradually weakens with increasing temperature,indicating the potential of this material as a low-temperature sensor.
基金financially supported by the National Natural Science Foundation of China(Nos.52472105,52272246,and 12074015)the Sichuan Science and Technology Program(Nos.2024YFHZ0309 and 2023NSFSC1596)the State Key Laboratory for Mechanical Behavior of Materials(No.20232509).
文摘Compositing a secondary phase in Ag_(2)Se can usually tune the electron and phonon scattering to improve the thermoelectric performance.However,the intrinsically high carrier concentration still limits the performance optimization.Here,we employ a modulation decoration strategy to simultaneously achieve submicron-scale constituents and compositional modification for synergistic optimization of thermoelectric properties.Amorphous nano Sb_(2)S_(3) has been decorated on the surface of Ag_(2)Se powders,and S was added into the Ag_(2)Se matrix through an ion exchange reaction accompanied by the formation of a crystal/amorphous mixed secondary phase of Sb_(2)(S,Se)_(3).The S doping reduced the excessive intrinsic carrier concentration,leading to modified electrical transport properties and significantly reduced electrical thermal conductivity.On the other hand,introducing the S dopants and the crystal/amorphous interfaces into the Ag_(2)Se matrix could increase the lattice anharmonicity,further contributing to the reduced thermal conductivity.Consequently,the Ag_(2)Se-0.4%Sb_(2)S_(3) sample obtains a high average zT value of>1 in the temperature range of 300–390 K.In addition,the maximum cooling temperature difference of over 85 K can be predicted in an Ag_(2)Se/Ag_(2)Se-0.4%Sb_(2)S_(3) segregated module at the hot side temperature of 350 K.
基金the financial support from the Guangdong Basic and Applied Basic Research Foundation(Grant No.2024A1515140104)National Natural Science Foundation of China(Grants No.62504043)the funding from the State Key Laboratory of Optoelectronic Materials and Technologies at Sun Yat-sen University(Grant No.OEMT-2022-ZTS-08)。
文摘The inkjet-printed Cu_(2)ZnSn(S,Se)_(4)(CZTSSe)has garnered extensive attention owing to its costeffectiveness,high-throughput fabrication,and roll-to-roll compatibility.However,selenium volatility loss during high-temperature selenization induces detrimental defects in both bulk and interface,limiting CZTSSe solar cell performance.Here,we develop a simple and controllable low-temperature selenium post-treatment(Se-LPT)strategy to compensate for the selenium loss.Systematic studies reveal that the Se-LPT can effectively passivate selenium vacancy deep-level defects in the CZTSSe absorber and suppresses carrier nonradiative recombination,thereby reducing the open-circuit voltage deficit from 336to 298 mV.Furthermore,this treatment lowers the carrier transport barrier and facilitates efficient carrier transport by reducing the spike-like conduction band offset at the heterojunction interface.The enhanced carrier density and conductivity further contribute to the short-circuit current improvement.Consequently,the Se-LPT CZTSSe devices deliver an efficiency of 14.13%,representing the highest performance reported to date for inkjet-printed CZTSSe solar cells.This work demonstrates an effective route for developing cost-effective and high-efficiency CZTSSe photovoltaics.
文摘To improve the thermal insulation performance of SiO_(2)aerogels at high temperatures,SiO_(2)precursor solutions were prepared via a sol-gel two-step method.Fe_(2)O_(3)powder was extra added as an opacifier to the SiO_(2)precursor solutions with mass fractions of 0,0.2%,0.5%,1.0%,and 3.0%;and Fe_(2)O_(3)-SiO_(2)composite aerogels were fabricated using CO_(2)supercritical drying technology.The effects of the Fe_(2)O_(3)extra addition on the aerogels were investigated.The results show that:(1)Fe_(2)O_(3)doping does not alter the aerogel morphology;Fe_(2)O_(3)suppresses the mass loss at high temperatures and enhances the high-temperature stability of the composite;(2)below 800℃,the aerogel with 0.5%Fe_(2)O_(3)exhibits the lowest thermal conductivity and the best thermal insulation performance;at 800-1000℃,the aerogel with 1%Fe_(2)O_(3)exhibits the lowest thermal conductivity and a good nanoporous structure;(3)by adjusting the Fe_(2)O_(3)extra addition,composite aerogels suitable for different temperature ranges can be tailored.
基金the Alliance Project of Shanghai City in China(LM201641)。
文摘Two different Mn-Ce-O_(x)/TiO_(2) catalysts were prepared by ordinary impregnation(denoted as MCT) and citric acid assisted impregnation(denoted as MCT-CA) methods,respectively.Excellent NOxremoval is achieved over MCT-CA for selective catalytic reduction with NH3(NH_(3)-SCR),and 100% NOxconversion is obtained at 125℃ under weight hour space velocity(WHSV) of 80000 mL/(gcat·h).Particularly,100% NOxis converted on MCT-CA in the presence of 10 vol% H2O at 175℃.As H2O and SO2coexist in the reaction system for 9 h,NO_(x) conversion can still be maintained>90%,much higher than that(22%) of MCT.A series of characterization results indicates that MCT-CA exhibits a larger BET specific surface area,pore volume,and pore size,which enhances the dispersion of Mn and Ce oxides and promotes the rapid adsorption of reactants and desorption of products.Additionally,MCT-CA possesses more Mn^(4+),Ce^(3+),chemisorbed oxygen species,and stronger reducibility,facilitating the co nversion of NO to NO_(2).Specially,the amount of active NH_(3) species and active nitrate species on MCT-CA is much more than that over MCT,The combined effect of the aforementioned factors devotes to the excellent low-temperature SCR performance and tolerance to H2O/SO2over MCT-CA.
基金supports from the National Natural Science Foundation of China(51901204,52161023,52271249)Science and Technology project of Yunnan Precious Metal Laboratory(YPML-2023050208)+1 种基金Yunnan Science and Technology Planning Project(202201AU070010,202301AT070276,202302AB080008,202303AA080001)supported by Yunnan Key Laboratory of Electromagnetic Materials and Devices.
文摘In recent years,modification of texture distribution has been considered a valid approach to improve the room-temperature(RT)formability of magnesium(Mg)alloys.In this study,a novel Mgsingle bond2Znsingle bond3Lisingle bond1Gd alloy sheet with weak elliptical-texture was fabricated by cold rolling and subsequent annealing,and it showed an excellent Erichsen(IE)value near 7.1 mm.Both quasi-in-situ electron backscatter diffraction(EBSD)and transmission electron microscopy(TEM)analysis indicate that considerable basal and pyramidal dislocations can be activated in the cold rolling process.During annealing,these dislocations can induce nucleation and then cause preferential misorientation relationships around〈uvt0〉concerning the nuclei and parent grains,which can facilitate the formation of elliptical texture.Furthermore,the particle-stimulated nucleation(PSN)mechanism and the co-segregation of Zn and Gd at grain boundaries(GB)further weak texture intensity.Finally,the mechanical properties of the Mgsingle bond2Znsingle bond3Lisingle bond1Gd alloy sheet are significantly improved.
基金the financial support from Projects of Science&Technology Department of Sichuan Province(Grant No.22023YFG0082,Grant No.2023YFG0096,and Grant No.2023ZHJY0019)Chengdu Science and Technology Projects(Grant No.2024-YF08-00062-GX).
文摘Efficient,safe,and reliable energy output from high-energy-density lithium metal batteries(LMBs)at all climates is crucial for portable electronic devices operating in complex environments.The performance of corresponding cathodes and lithium(Li)metal anodes,however,faces significant challenges under such demanding conditions.Herein,a nonflammable electrolyte for high-voltage Li‖LCO cells has been designed,including partially-fluorinated ethyl 4,4,4-trifluorobutyrate(ETFB)as the key solvent,guided by theoretical calculations.With this ETFB-based electrolyte,Li‖LCO cells exhibit enhanced reversible capacities and superior capacity retention at an elevated charge voltage of 4.5 V and a wide operating temperature range spanning from-60℃to 70℃.The cells achieve 67.1%discharge capacity at-60℃,relative to room temperature capacity,and 85.9%100th-cycle retention at 70℃.The outstanding properties are attributed to the LiF-rich interphases formed in the ETFB-based electrolyte with a finetuned solvation structure,in which the coordination environment in the vicinity of Li^(+)cations and the distance between anion and solvents are subtly adjusted by introducing ETFB.This solvation structure has been mutually elucidated through joint spectra characterizations and atomistic simulations.This work presents a new strategy for the design of electrolytes to achieve all-climate reliable and safe application of LMBs.
基金supported by the National Natural Science Foundation of China (Nos. 22371165, 21971143, 22209098)the Natural Science Foundation of Hubei Province (No. 2022CFB326)+3 种基金the 111 Project (No. D20015)ITOYMR in the Higher Education Institutions of Hubei Province (No. T201904)the Key Project Foundation of Hubei Three Gorges Laboratory (No. Z2022078)the Opening Foundation of Hubei Three Gorges Laboratory (No. SK213002)。
文摘Constructing high-performance electrocatalysts for oxygen evolution reaction(OER) using a simple and economical strategy is considerably meaningful yet still challenging. Herein, Co(OH)_(2)/Mo_(2)Ti C_(2)T_(x)(where Txrepresents the surface functional groups,-O,-OH and-F) hetero-nanosheets were facilely prepared by the in situ topochemical transformation at room temperature towards efficient OER. The integrity of Co(OH)_(2)nanosheets and Mo_(2)Ti C_(2)T_(x) nanosheets affords interfacial coupling to optimize the electronic structures of Co and Mo ions, which endows the high electron transfer efficiency and rapid reaction kinetics. As a result, the Co(OH)_(2)/Mo_(2)Ti C_(2)T_(x) hetero-nanosheets exhibit excellent OER performances with low overpotentials of 283 m V on glass-carbon electrode, and 227 m V on nickel foam at 10 m A/cm^(2). Furthermore, the decent anti-alkali ability underpins superior operational stability exceeding 100 h, demonstrating grand potential in practical applications. This work provides a new insight for the synthesis of efficient and cost-effective two-dimensional(2D) material-based electrocatalysts.
基金financially supported by the National Natural Science Foundation of China(52222005,52100133)the Key R&D Program of Yunnan Province(202303AC100008)。
文摘Catalytic regeneration is a key approach to solving high energy consumption issues in the amine-based CO_(2)absorption method.Previous studies have shown that loaded acid sites(such as SO_(4)^(2-))are beneficial for promoting low-temperature CO_(2)-rich amine regeneration,but their weak binding strength to the support results in limited catalyst life.Herein,we proposed an advanced catalyst modification strategy to maintain the active hydroxyl group(Zr-OH-Fe)via actively transferring electrons on the surface of FeZrO_(x)nano-heterojunction.Combining in situ DRIFTS and DFT calculations,we revealed that the ZrOH-Fe at the ZrO_(2)-Fe_(2)O_(3)heterointerfaces exhibit enhanced proton-donating ability,with deprotonation energy reduced from 2.94 to 2.61 eV compared to Zr-OH(which should be called inert hydroxyl group).This improvement favors the rate-determining proton transfer step from RNH_(3)^(+)to RNHCOO^(-).Surprisingly,it increased the CO_(2)desorption rate by 10.5 times and reduced the energy consumption by 43.6%during amine regeneration.This work offers a practical strategy for improving the performance of lowtemperature CO_(2)-rich amine regeneration catalysts,and the low-cost recyclability of amine used in CO_(2)capture.
基金supported by the National Natural Science Foundation of China(No.52202090)the Fundamental Research Funds for the Central Universities(No.2082019014).
文摘Thorium dioxide(ThO_(2))fibers exhibit exceptional structural stability,low density and superior flexibility,coupled with a remarkably high melting point,positioning them as promising candidates for thermal protection applications.Additionally,their commendable secondary processing characteristics enable the development of diverse composite materials when integrated with other materials,significantly broadening the potential utilization of ThO_(2)materials and thorium resources in industrial fields.In this work,the ThO_(2)fiber was fabricated by the sol-gel precursor method,and the precursor with good spinnability and excellent stability was synthesized for the first time.The ThO_(2)fiber with a mean diameter of 868 nm is both highly flexible and strong(max.tensile strength 2.21 MPa),capable of bending freely across a wide temperature range from-196℃(in liquid nitrogen)to 1200℃.Meanwhile,it exhibits excellent temperature stability and heat insulation properties.The ThO_(2)nanofiber membranes with layered structure have low density(32-37 mg·cm^(-3)),low thermal conductivity(27.3-30.1 mW·m^(-1)·K^(-1)@25℃).The ThO_(2)nanofiber membranes with 15 mm thickness can reduce the temperature from 1200 to 282℃and maintain a high aspect ratio and bendability after 1200℃@90 min.The results show that the ThO_(2)fiber can be used as a new kind of high-temperature resistant material.
基金supported by Guizhou Provincial Key Technology R&D Program(No.[2022]052).
文摘Uniaxial tensile testing explored the Portevin-Le Chatelier(PLC)effect in nickel-based superalloys featuring high Mo/Cr mass ratios,focusing on the influence of variations in the initial microstructure on the deformation behavior at room and elevated temperatures.Experimental results indicated that the PLC effect was observed solely in the high-temperature tensile curves.However,the deformation mechanisms and characteristics of the PLC effect varied with different initial microstructures.Solid solution(SS)and over-aged(OA)samples exhibited C-type serrations,while under-aged(UA)and peak-aged(PA)specimens,featuring short-and long-range ordered phases,respectively,exhibited A+B type serrations in their tensile curves.Microstructural evolution from the SS to the UA,PA and OA states changed their stacking fault energy(SFE),leading to a sequential transformation in the plastic deformation mechanisms during high-temperature tensile deformation:stacking fault(SF)→nanotwin→microtwin→SF.C-type serrations in the SS samples were associated with high solute-atom contents and SF formation.The PLC effects in the UA and PA samples were predominantly caused by solute atom pinning dislocations.Although precipitates and twins were not the primary drivers of the PLC effect,they impeded dislocation migration,exacerbated solute-atom segregation and enhanced dislocation pinning,generating A+B-shaped serrations.In the OA specimens,precipitated phases induced interfacial mismatch under thermal-force coupling.SF shearing of the precipitated phase and subsequent re-dissolution facilitated the formation of C-type serrations,whose PLC effect was induced by the combined action of dynamic strain aging(DSA),SFs of the matrix and diffusion-controlled pseudo-locking mechanisms.
基金supported by the National Natural Science Foundation of China(52170118,52322004,52230002)the China Postdoctoral Science Foundation(2024M763296).
文摘The development of efficient low-load platinum catalysts for CO oxidation is critical for large-scale industrial applications and environmental protection.In this study,a strategy of N_(2)treatment triggered the self-reforming into fully exposed Pt cluster catalysts was proposed.By adjusting the coordination environment of Pt species on the defect support through N_(2)treatment,the CO catalytic activity was significantly enhanced,achieving complete CO oxidation at 130℃with a Pt loading of only 0.1 wt.%.The turnover frequency of N_(2)-treated Pt_(FEC)/Ti-D at 160℃was 18.3 times that of untreated Pt_(SA)/Ti-D.Comprehensive characterization results indicated that the N_(2)treatment of the Pt single-atom defect catalyst facilitated the reconfiguration and evolution of the defect structure,leading to the aggregation of Pt single atoms into fully exposed Pt clusters.Notably,these fully exposed Pt clusters exhibited a reduced coordination of Pt–O in the first coordination shell compared to single atoms,which resulted in the formation of Pt–Pt metal coordination.This unique coordination structure enhanced the adsorption and activation of CO and O_(2)on the catalyst,thereby resulting in exceptionally low-temperature CO oxidation activity.This work demonstrates a promising strategy for the design,synthesis,and industrial application of efficient low-platinum load catalysts.
基金supported by the National Natural Science Foundation of China(No.52471040)the Natural Science Foundation of Shandong Province(No.ZR2022ME005).
文摘An Al_(2)O_(3)/Al-Cu-Mn composite was fabricated using a combination of ball milling and liquid-solid reaction,with a nominal composition of Al-4Cu-0.5Mn-2.8γ-Al_(2)O_(3).The composite contains reinforcement particles,including nano-sizedθ’and T(Al_(20)Cu_(2)Mn_(3))particles after T6 heat treatment,as well as in-situ synthesized nano-sizedγ-Al_(2)O_(3)particles.Tensile tests of the Al-4Cu-0.5Mn-2.8γ-Al_(2)O_(3)composite and the Al-4Cu-0.5Mn base alloy after T6 treatment were carried out at room temperature and elevated temperatures(200°C,300°C,and 400°C).Compared with the base alloy,the yield strength of the Al-4Cu-0.5Mn-2.8γ-Al_(2)O_(3)composite after T6 treatment increases significantly from 187 MPa to 263 MPa at room temperature.Simultaneously,at elevated temperatures,the yield strength is also enhanced,with a yield strength of 52 MPa at 400°C for this composite.The in-situ fabricatedγ-Al_(2)O_(3)particles,mainly distributed along the grain boundaries,are supposed to play the main strengthening role,especially at high temperatures.This work acts as a reference for designing composites for high-temperature applications.
基金financially supported by the National Natural Science Foundation of China(Nos.51975175,51875158)。
文摘The fracture behavior at high temperatures of the Ti−22Al−26Nb alloy,which features duplex lamellar,bimodal,and Widmanstätten structures,was studied.Samples of the alloy were prepared through compression deformation in the trans-phase region followed by subsequent heat treatment.The results indicate that at 650℃,the fracture toughness of the Ti−22Al−26Nb alloy is increased by 41.7%compared to that with original microstructures.The content of the B2 phase significantly influences the inherent fracture toughness of the material,while the morphology and distribution of the precipitated phases primarily affect the tortuosity of the crack propagation path.Among the microstructural features,the morphology and geometric orientation of the lamellae most significantly impact the crack path;consequently,the Widmanstätten structure exhibits the most tortuous fracture path.Additionally,a predictive model for fracture toughness is developed,which effectively predicts the fracture toughness of Ti−22Al−26Nb alloys with various microstructures at 650℃.
基金supported by the Sanming University(No.23YG05)the Science Foundation of Fujian Province(No.2023J011027).
文摘Formaldehyde(HCHO)is a significant indoor pollutant found in various sources and poses potential health risks to humans.Noble metal catalysts show efficient and stable catalytic activity for ambient-temperature HCHO oxidation,yet suffer from low metal utilization.Efforts focus on designing catalysts with enhanced intrinsic activity and reduced noble metal loading.In this study,we developed a simple pretreatment method using ammonia solution on SiO_(2)carrier to enhance the activity of the Pd/SiO_(2)catalyst for HCHO oxidation.After the carrier was pretreated with an ammonia solution,a significant promoting effect was observed on the Pd/SiO_(2)(NH_(3)·H_(2)O)-R catalyst.It achieved almost complete oxidation of 150 ppmV of HCHO at 25℃,much better than the Pd/SiO_(2)-R(5%HCHO conversion rate).Multiple characterization results indicated that the ammonia solution pretreatment of the SiO_(2)carrier increased the surface defects,facilitating the anchoring of Pd nanoparticles and increasing their dispersion.The increase dispersion of Pd resulted in the generation of additional oxygen vacancies on the catalyst surfaces.The increased in oxygen vacancies on the catalyst was beneficial for enhancing the catalyst's ability to activate H_(2)O to form surface hydroxyl groups,thereby accelerating the catalytic oxidation process of HCHO.The reaction mechanism of HCHO on the Pd/SiO_(2)(NH_(3)·H_(2)O)-R catalyst mainly follows an efficient pathway:firstly,the HCHO being oxidized by surface active hydroxyl groups to formate;subsequently,the formate being oxidized by hydroxyl groups to H_(2)O and CO_(2).This study provides a promising strategy for designing high-performance noble metal catalysts for HCHO catalytic oxidation.
基金the National Natural Science Foundation of China(Nos.22125604,22106100,21976117,22276119)Shanghai Rising-Star Program(No.22QA1403700).
文摘Developing a high-efficiency catalyst with both superior low-temperature activity and good N_(2)selectivity is still challenging for the NH_(3)selective catalytic reduction(SCR)of NO_(x)from mobile sources.Herein,we demonstrate the improved low-temperature activity and N_(2)selectivity by regulating the redox and acidic properties of MnCe oxides supported on etched ZSM-5 supports.The etched ZSM-5 enables the highly dispersed state of MnCeOx species and strong interaction between Mn and Ce species,which promotes the reduction of CeO2,facilitates electron transfer from Mn to Ce,and generates more Mn^(4+)and Ce^(3+)species.The strong redox capacity contributes to forming the reactive nitrate species and-NH_(2)species from oxidative dehydrogenation of NH_(3).Moreover,the adsorbed NH_(3)and-NH_(2)species are the reactive intermediates that promote the formation of N_(2).This work demonstrates an effective strategy to enhance the low-temperature activity and N_(2)selectivity of SCR catalysts,contributing to the NO_(x)control for the low-temperature exhaust gas during the cold-start of diesel vehicles.
基金supported by the National Natural Science Foundation of China(U23B2075)the Natural Science Foundation of Shandong Province(ZR202111290333)the China Postdoctoral Science Foundation(2023M730640,2024M750490).
文摘Sodium-ion batteries with ZnIn_(2)S_(4)(ZIS)anodes promise a high capacity and abundant resources.However,their inherent low conductivity,large volume expansion and sluggish Na+diffusion limit the development of the wide-temperature sodium storage.This study pioneers a scalable synthesis of hierarchical hollow structural ZIS/C heterostructure through in situ confined growth of ZIS nanosheets in porous hollow carbon spheres(PHCSs)via a hydrothermal method.This unique structure exhibits abundant heterostructures to facilitate charge transport,rich porous structures to promote electrolyte wettability,efficient space utilization to relieve volume expansion,as well as interconnected carbon networks to ensure framework stability.Consequently,ZIS/C exhibits exceptional cycling stability with 92%capacity retention after 1000 cycles.Notably,ZIS/C demonstrates good wide-temperature performance operating at–50∼90°C,especially,at–30°C with a capacity of 208 mA h g^(−1)at 0.3A g^(−1).The full cell of ZIS/C||Na_(3)V_(2)(PO_(4))_(3)exhibits excellent high-rate capability(178 mA h g^(−1)at 6A g^(−1)).
