Morphology and growth rate of carbon dioxide hydrate on the interface between liquid carbon dioxide and humic acid solutions were studied in this work.It was found that after the growth of the hydrate film at the inte...Morphology and growth rate of carbon dioxide hydrate on the interface between liquid carbon dioxide and humic acid solutions were studied in this work.It was found that after the growth of the hydrate film at the interface,further growth of hydrate due to the suction of water in the capillary system formed between the wall of the cuvette and the end boundary of the hydrate layer occurs.Most probably,substantial effects on the formation of this capillary system may be caused by variations in reactor wall properties,for example,hydrophobic-hydrophilic balance,roughness,etc.We found,that the rate of CO_(2) hydrate film growth on the surface of the humic acid aqueous solution is 4-fold to lower in comparison with the growth rate on the surface of pure water.We suppose that this is caused by the adsorption of humic acid associates on the surface of hydrate particles and,as a consequence,by the deceleration of the diffusion of dissolved carbon dioxide to the growing hydrate particle.展开更多
Although poly(lactic acid)(PLA)is a good environmentally-friendly bio-degradable polymer which is used to substitute traditional petrochemical-based polymer packaging films,the barrier properties of PLA films are stil...Although poly(lactic acid)(PLA)is a good environmentally-friendly bio-degradable polymer which is used to substitute traditional petrochemical-based polymer packaging films,the barrier properties of PLA films are still insufficient for high-barrier packaging applications.In this study,oxygen scavenger hydroxyl-terminated polybutadiene(HTPB)and cobalt salt catalyst were incorporated into the PLA/poly(butylene adipate-co-terephthalate)(PLA/PBAT),followed by melting extrusion and three-layer co-extrusion blown film process to prepare the composite films.The oxygen permeability coefficient of the composite film combined with 6 wt%oxygen scavenger and 0.4 wt%catalyst was decreased significantly from 377.00 cc·mil·m^(-2)·day^(-1)·0.1 MPa^(-1) to 0.98 cc·mil·m^(-2)·day^(-1)·0.1 MPa^(-1),showing a remarkable enhancement of 384.69 times compared with the PLA/PBAT composite film.Meanwhile,the degradation behavior of the composite film was also accelerated,exhibiting a mass loss of nearly 60%of the original mass after seven days of degradation in an alkaline environment,whereas PLA/PBAT composite film only showed a mass loss of 32%.This work has successfully prepared PLA/PBAT composite films with simultaneously improved oxygen barrier property and degradation behavior,which has great potential for high-demanding green chemistry packaging industries,including food,agricultural,and military packaging.展开更多
Because of their low electrical conductivity,sluggish ion diffusion,and poor stability,conventional electrode materials are not able to meet the growing demands of energy storage and portable devices.Graphene assemble...Because of their low electrical conductivity,sluggish ion diffusion,and poor stability,conventional electrode materials are not able to meet the growing demands of energy storage and portable devices.Graphene assembled films(GAFs)formed from graphene nanosheets have an ultrahigh conductivity,a unique 2D network structure,and exceptional mechanical strength,which give them the potential to solve these problems.However,a systematic understanding of GAFs as an advanced electrode material is lacking.This review focuses on the use of GAFs in electrochemistry,providing a comprehensive analysis of their synthesis methods,surface/structural characteristics,and physical properties,and thus understand their structure-property relationships.Their advantages in batteries,supercapacitors,and electrochemical sensors are systematically evaluated,with an emphasis on their excellent electrical conductivity,ion transport kinetics,and interfacial stability.The existing problems in these devices,such as chemical inertness and mechanical brittleness,are discussed and potential solutions are proposed,including defect engineering and hybrid structures.This review should deepen our mechanistic understanding of the use of GAFs in electrochemical systems and provide actionable strategies for developing stable,high-performance electrode materials.展开更多
ZrCoRE(RE denotes rare earth elements)non-evaporable getter films have significant applications in vacuum packaging of micro-electro mechanical system devices because of their excellent gas adsorption performance,low ...ZrCoRE(RE denotes rare earth elements)non-evaporable getter films have significant applications in vacuum packaging of micro-electro mechanical system devices because of their excellent gas adsorption performance,low activation temperature and environmental friendliness.The films were deposited using DC magnetron sputtering with argon and krypton gases under various deposition pressures.The effects of sputtering gas type and pressure on the morphology and hydrogen adsorption performance of ZrCoRE films were investigated.Results show that the films prepared in Ar exhibit a relatively dense structure with fewer grain boundaries.The increase in Ar pressure results in more grain boundaries and gap structures in the films.In contrast,films deposited in Kr display a higher density of grain boundaries and cluster structures,and the films have an obvious columnar crystal structure,with numerous interfaces and gaps distributed between the columnar structures,providing more paths for gas diffusion.As Kr pressure increases,the film demonstrates more pronounced continuous columnar structure growth,accompanied by deeper and wider grain boundaries.This structural configuration provides a larger specific surface area,which significantly improves the hydrogen adsorption speed and capacity.Consequently,high Ar and Kr pressures are beneficial to improve the adsorption performance.展开更多
High-quality antiferromagnetic(AFM)θ-phase manganese nitride(MnN)films were successfully grown on MgO(001)substrates by plasma-assisted molecular beam epitaxy.Structural analysis confirms the high-quality MnN film ha...High-quality antiferromagnetic(AFM)θ-phase manganese nitride(MnN)films were successfully grown on MgO(001)substrates by plasma-assisted molecular beam epitaxy.Structural analysis confirms the high-quality MnN film has a tetragonal distortion with a c/a ratio of~0.98.The film exhibits exceptional stability in both aqueous and ambient conditions,which is a crucial factor for practical applications.Electrical transport reveals its metallic behavior with an upturn at low temperatures,which could be attributed to the Kondo effect originated from nitrogen vacancy-induced magnetic impurities.Room temperature exchange bias has been demonstrated in a MnN/CoFeB heterostructure,verifying the AFM ordering of MnN.Considering its high Néel temperature~650 K,superior stability,and low-cost,this work highlights the epitaxial MnN films as a promising candidate for AFM spintronic applications.展开更多
Impact of texture type on the magnetic properties of ultrahigh density perpendicular magnetic recording media L1_(0)-FePt thin film was investigated,so were the texture formation and evolution mechanism.Reuss,Voigt,an...Impact of texture type on the magnetic properties of ultrahigh density perpendicular magnetic recording media L1_(0)-FePt thin film was investigated,so were the texture formation and evolution mechanism.Reuss,Voigt,and Hill models were used to determine the anisotropic elastic modulus of L1_(0)-FePt thin film with fiber texture.Then,the elastic strain energies of thin films under various stress conditions were calculated.Results reveal that the stress condition has a significant influence on the fiber texture evolution.When the L1_(0)-FePt thin film is subjected to compressive in-plane strain prior to ordering phase transformation,the formation of{100}fiber texture is promoted.On the contrary,the ordering phase transformation under tensile in-plane strain promotes the{001}fiber texture formation.展开更多
Ising superconductivity has garnered much attention in recent years due to its extremely high in-plane upper critical field (B_(c2)).Here,we fabricated 14 multilayer Pb_(1-x)Bi_(x) (0%≤x≤40%) thin films on Si (111)-...Ising superconductivity has garnered much attention in recent years due to its extremely high in-plane upper critical field (B_(c2)).Here,we fabricated 14 multilayer Pb_(1-x)Bi_(x) (0%≤x≤40%) thin films on Si (111)-7×7 reconstructed surface by molecular beam epitaxy.Large B_(c2) beyond the Pauli limit is observed in all the Pb_(1-x)Bi_(x) films,indicating that they may exhibit characteristics of Ising superconductivity.Moreover,the introduction of Bi doping can significantly enhance and effectively tune the in-plane B_(c2) of Pb_(1-x)Bi_(x) films,which will help us better understand Ising superconductivity and provide a new platform for the development of tunable Ising superconductors.展开更多
This study aimed to develop and characterize biodegradable packaging film from blends of two natural polysaccharides,i.e.,agar and glucomannan.The glucomannan used was derived from the specific tuber plant Amorphophal...This study aimed to develop and characterize biodegradable packaging film from blends of two natural polysaccharides,i.e.,agar and glucomannan.The glucomannan used was derived from the specific tuber plant Amorphophallus oncophyllus(locally known as“porang”),which grows abundantly in Indonesian forests and remains underutilized.Various ratios of agar and porang-glucomannan(PG)proportions were formulated to produce a food packaging film,which was subsequently tested for its mechanical,physical,chemical,and thermal properties.The results showed that the inclusion of PG to the film formulations notably enhanced the stretchability of agar films,achieving maximum a twofold increase,while concurrently reducing their water resistance such as increased water solubility and water swelling for up to 125%and 105%,respectively.The mechanical and thermal properties,as well as the water vapor permeability of the resulting film,were significantly affected by the polymer matrix structure formed by the varying proportions of the two biopolymers.The enhancement of these properties was associated with a more solid/compact film structure,as corroborated by cross-sectional images obtained through SEM analysis.The study’s findings suggest that utilizing agar and porang biomass has significant potential for further development as an environmentally friendly food packaging material.展开更多
The discovery of high-temperature superconductivity in bilayer nickelate La_(3)Ni_(2)O_(7)under high-pressure conditions has spurred extensive efforts to stabilize superconductivity at ambient pressure.Recently,the re...The discovery of high-temperature superconductivity in bilayer nickelate La_(3)Ni_(2)O_(7)under high-pressure conditions has spurred extensive efforts to stabilize superconductivity at ambient pressure.Recently,the realization of superconductivity in compressively strained La_(3)Ni_(2)O_(7)thin films grown on the SrLaAlO_(4)substrates,with a T_(c)exceeding 40 K,represents a significant step toward this goal.Here,we investigate the influence of film thickness and carrier doping on the electronic structure of La_(3)Ni_(2)O_(7)thin films,ranging from 0.5 to 3 unit cells,using first-principles calculations.For a 2 unit-cell film with an optimal doping concentration of 0.3 hole per formula unit(0.15 hole/Ni),the Ni-d_(z^(2))interlayer bonding state crosses the Fermi level,resulting in the formation ofγpockets at the Fermi surface.These findings align with angle-resolved photoemission spectroscopy experimental data.Our results provide theoretical validation for the recent experimental discovery of ambient-pressure superconductivity in La_(3)Ni_(2)O_(7)thin films and underscore the significant impact of film thickness and carrier doping on electronic property modulation.展开更多
Petrochemical plastics are widely used for food protection and preservation;however,they exhibit poor biodegradability,resisting natural degradation through physical,chemical,or enzymatic processes.As a sustainable al...Petrochemical plastics are widely used for food protection and preservation;however,they exhibit poor biodegradability,resisting natural degradation through physical,chemical,or enzymatic processes.As a sustainable alternative to conventional plastic packaging,edible films offer effective barriers against moisture,gases,and microbial contamination while being biodegradable,biocompatible,and environmentally friendly.In this study,novel active food packaging materials(in film form)were developed by incorporating starch,carrageenan,nanocellulose(NC),Aloe vera,and hibiscus flower extract.The effects of varying the matrix composition(26.5–73.5 wt.%starch/carrageenan),NC concentration(2.77-17.07 wt.%),and particle type(fibers or crystals)on the film structure and characteristics were analyzed using various methods.Scanning electron microscopy demonstrated good homogeneity and effective dispersion of NC within the blendmatrix.An increased carrageenan content in the filmimproved wettability,moisture absorption,solubility,and water vapor permeability.The mechanical properties of the films were enhanced by NC incorporation and higher carrageenan content.The developed films also exhibited effective UV radiation barriers and biodegradability.Films with low carrageenan content(less than 33.3%)and high NC content(7%,10% crystals or 10%,15% fibers)exhibited optimal properties,including enhanced water resistance,hydrophobicity,and mechanical strength,along with reduced water vapor permeability.However,the high water solubility and moisture absorption(above 55% and 14%,respectively)indicated their unsuitability as packaging materials for food products with wet surfaces and high humidity.The results suggest that these films are well suited for use as edible food packaging for fruits and vegetables.展开更多
Flexible thermoelectric thin films offer a promising avenue for the development of portable and sustainable flexible power supplies.However,a lack of thin films with excellent performance restricts their application i...Flexible thermoelectric thin films offer a promising avenue for the development of portable and sustainable flexible power supplies.However,a lack of thin films with excellent performance restricts their application in flexible thermoelectric devices.In this study,high-performance BiSbTe films are successfully prepared using a combination of magnetron sputtering and thermal diffusion.By optimizing carrier concentration to~4.47×10^(19)cm^(−3)and simultaneously realizing high carrier mobility of>120 cm^(2)·V^(−1)·s^(−1),an impressive room-temperature power factor of 24.13μW·cm^(−1)·K^(−2)is achieved in a Bi_(0.4)Sb_(1.6)Te_(3)thin film.The flexible Bi_(0.4)Sb_(1.6)Te_(3)thin film also demonstrates excellent bending resistance and stability(ΔR/R_(0)<5%,ΔS/S_(0)<5%,andΔS^(2)σ/S_(0)^(2)σ_(0)<10%)after 1000 bending cycles at a minimum bending radius of 6 mm.A flexible thin-film thermoelectric device assembled with p-type Bi_(0.4)Sb_(1.6)Te_(3)legs achieves a remarkable power output of~82.15 nW and a power density of~547.68μW·cm^(−2)under a temperature difference of 20 K.展开更多
Polyimide(PI)is widely used in high-tech fields such as microelectronics,aerospace,and national defense because of its excellent optical properties,high-and low-temperature resistance,and good dimensional stability.To...Polyimide(PI)is widely used in high-tech fields such as microelectronics,aerospace,and national defense because of its excellent optical properties,high-and low-temperature resistance,and good dimensional stability.To achieve the desired properties of PI,the monomers 2,6-diaminopyrimidin-4-ol(DAPD)and 6-(2,3,5,6-tetrafluoro-4-vinylphenoxy)pyrimidin-2,4-diamine(DAFPD),which contains crosslinkable functional groups,were designed and synthesized successfully and copolymerized with 4,4'-oxydianiline(ODA)and 4,4-hexafluoroisopropylphthalic anhydride(6FDA).The prepared PI film(PI-3),with rigid backbones and loose packing had excellent heat resistance(Td5%=489℃)and optical properties(T450=82%).Furthermore,a crosslinked PI film(c-PI-3)with more heat-resistant(Td5%=524℃)and better mechanical properties(σ=125.46MPa),can be obtained through thermal crosslinking of tetrafluorostyrene.In addition,the changes in the properties caused by the proportion of DAFPD added during copolymerization are discussed comprehensively.This study provides a promising candidate for heat-resistant PI materials.展开更多
[Background and purposes]Proton exchange membrane fuel cells(PEMFCs),which convert hydrogen energy directly into electrical energy and water,have received overwhelming attention,owing to their potential to significant...[Background and purposes]Proton exchange membrane fuel cells(PEMFCs),which convert hydrogen energy directly into electrical energy and water,have received overwhelming attention,owing to their potential to significantly reduce energy consumption,pollution emissions and reliance on fossil fuels.Bipolar plates are the major part and key component of PEMFCs stack,which provide mechanical strength,collect and conduct current segregate oxidants and reduce agents.They contribute 70-80%weight and 20-30%cost of a whole stack,while significantly affecting the power density.There are three types plates,including metal bipolar plate,graphite bipolar plate and composite bipolar plate.Stainless steel bipolar plates,as one of metal bipolar plate,exhibit promising manufacturability,competitive cost and durability among various metal materials.However,stainless steel would be corroded in the harsh acid(pH 2-5)and humid PEMFCs environment,whereas the leached ions will contaminate the membrane.In addition,the passivated film formed on the surface will increase the interfacial contact resistance(ICR).In order to improve the corrosion resistance and electrical conductivity of steel bipolar plates,surface coatings are essential.Metal nitride coatings,metal carbide coatings,polymer coatings and carbon-based coatings have been introduced in recent years.Carbon-based coatings,mainly including a-C(amorphous Carbon),Ta-C(Tetrahedral amorphous carbon)and DLC(diamond-like carbon),have attracted considerable attention from both academia and industry,owing to their superior performance,such as chemical inertness,mechanical hardness and electrical conductivity.However,Ta-C films as protective coating of PEMFCs have been rarely reported,due to the difficulty in production for industrial application.In this paper,multi-layer Ta-C composite films were produced by using customized industrial-scale vacuum equipment to address those issues.[Methods]Multiple layered Ta-C coatings were prepared by using PIS624 equipment,which assembled filtered cathodic arc evaporation,ion beam and magnetron sputtering into one equipment,while SS304 and silicon specimens were used as substrate for testing and analysis.Adhesion layer and intermediate layer were deposited by using magnetron sputtering at deposition temperature of 150℃and pressure of 3×10^(−1) Pa,while the sputtering current was set to be 5 A and bias power to be 300 V.The Ta-C layer was coated at arc current of 80-100 A,bias voltage of 1500 V and gas flow of 75 sccm.A scanning electron microscope(CIQTEK SEM3200)was used to characterize surface morphology,coating structure and cross-section profile of the coatings.Raman spectrometer(LabRam HR Evolution,HORIBA JOBIN YVON)was used to identify the bonding valence states.Electrochemical tests were performed by using an electrochemical work station(CHI760,Shanghai Chenhua Instrument Co.,Ltd.),with the traditional three electrode system,where saturated Ag/AgCl and platinum mesh were used as the reference electrode and counter electrode,respectively.All samples were mounted in plastic tube and sealed with epoxy resin,with an exposure area of 2.25 cm^(2),serving as the working electrode.Electrochemical measurements were carried out in simulated PEMFCs cathode environment in 0.5 mol·L^(−1) H_(2)SO_(4)+5 ppm F−solution,at operating temperature of 70℃.As the cathode environment was harsher than the anode environment,all the samples are stabilized at the open-circuit potential(OCP)for approximately 30 min before the EIS measurements.ICR between bipolar plates and GDL was a key parameter affecting performance of the PEMFCs stack.The test sample sandwiched between 2 pieces of carbon paper(simulate gas diffusion layer,GDL)was placed between 2 gold-plated copper electrodes at a compaction pressure of 1.4 MPa,which was considered to be the conventional compaction pressure in the PEMFCs.Under the same conditions,the resistance of a single carbon paper was measured as well.The ICR was calculated according to the formula ICR=1/2(R2−R1)×S,where S was the contact area between GDL and coated stainless steel BPPs.All data of ICR were measured three times for averaging.[Results]The coatings deposited by filtered cathodic arc technology were compact and smooth,which reduced coating porosity and favorable to corrosion resistance.The coating thickness of adhesion and intermediate layers were 180 nm,while the protective Ta-C coating thickness was about 300 nm,forming multiple coating to provide stronger protection for metal bipolar plates.Cr,Ti,Nb and Ta coatings were selected as adhesion layers for comparison.According to electrochemical test,Ta and Nb coatings have higher corrosion resistance.However,Ta and Nb materials would be costly when they are used for mass production.Relatively,Cr and Ti materials were cost effective.Hence,a comprehensive assessment was indispensable to decide the materials to be selected as adhesion layer.Ta-TiN and Ti-TiN combined adhesion and intermediate layer exhibited stronger corrosion resistance,with the corrosion current to be less than 10^(−6) A·cm^(−2).Ta-C protective coating deposited by using filtered cathodic arc technology indicated displayed higher corrosion resistance,with the average corrosion density to be about 1.26×10^(−7) A·cm^(−2).Ta-C coating also shown larger contact angle,with the highest hydrophobicity,which was one of the important advantages for Ta-C,in terms of corrosion resistance.According to Raman spectroscopy,the I(D)/I(G)=549.8/1126.7=0.487,with the estimated fraction of sp^(3) bonding to be in the range of 5154%.The intermediate layer TiN has higher conductivity than the CrN layer.Considering cost,corrosion performance and ICR result,the Ti-TiN layer combination is recommended for industrial scale application.[Conclusions]Multiple layer coating structure of Ta-C film had stronger corrosion resistance;with more than 50%sp^(3) content,while it also had larger water contact angle and higher corrosion resistance than DLC film.The filtered arcing deposition technology was able to make the film to be more consistent and stable than normal arcing technology in terms of the preparation of Ta-C.The coating displayed corrosion density of 1.26×10^(−7) A·cm^(−2) and ICR of less than 5 mΩ·cm^(2),far beyond technical target of 2025 DOE(US Department of Energy).This indicated that the mass-production scale coating technology for PEMFC bipolar plates is highly possible.展开更多
The early stages of crystallization and occurrence of surface wrinkling were investigated using poly(butadiene)-block-poly(ε-caprolactone)with an ordered lamellar structure.Direct evidence has demonstrated that surfa...The early stages of crystallization and occurrence of surface wrinkling were investigated using poly(butadiene)-block-poly(ε-caprolactone)with an ordered lamellar structure.Direct evidence has demonstrated that surface wrinkling precedes nucleation and crystal growth.This study examined the relationship between surface wrinkling,nucleation,and the formation of crystalline supramolecular structures using atomic force microscopy(AFM)and X-ray scattering measurements.Surface wrinkling is attributed to curving induced by accumulated stresses,including residual stress from the sample preparation and thermal stress during cooling.These stresses cause large-scale material flow and corresponding changes in the molecular conformations,potentially reducing the nucleation barrier.This hypothesis is supported by the rapid crystal growth observed following the spread of surface wrinkles.Additionally,the surface curving of the polymer thin film creates local minima of the free energy,facilitating nucleation.The nuclei subsequently grow into crystalline supramolecular structures by incorporating polymer molecules from the melt.This mechanism highlights the role of localized structural inhomogeneity in the early stages of crystallization and provides new insights into structure formation processes.展开更多
Long-time fermentation has always been one of the reasons restricting the development of straw biological pulping.This study aimed to develop a novel straw pulp film with shortened solid-state fermentation time with l...Long-time fermentation has always been one of the reasons restricting the development of straw biological pulping.This study aimed to develop a novel straw pulp film with shortened solid-state fermentation time with less than 20%mass loss rate by bio-pulping synergistic treatment of straw fibers with deep eutectic solvent(DES)and Streptomyces rochei(S.rochei).Results illustrated that at 3%S.rochei concentration with 7-day fermentation,both cellulose and hemicellulose enzyme activities of the treated rice straw fiber reached peak values with a fiber mass loss rate of 17.01%.Microstructural morphology revealed that S.rochei colonization initiated on straw surfaces and progressively penetrated internal structures,resulting in surface loosening and distinct disruption of cell wall tissues within vascular bundles in transverse sections.The treated rice straw strip indicated a maximum tensile strength of 46.22 MPa for(Bacteria)BA 3%at day 7,attributed to optimized synergistic effects of microfibril angle(MFA)and cellulose/hemicellulose relative content ratio.The modified straw pulp film exhibited significant enhancement in the tensile index(44.9%increase),burst index(10.3%increase),and tear index(60%increase)compared to untreated groups.This work demonstrated the important role ofDES and S.rochei bio-pulping synergistic treatment in improving rice straw pulp performance,suggesting an eco-friendly,novel,and efficient biomass pretreatment technology for potential application prospects in sustainable agricultural mulching materials.展开更多
Polymer adsorption at solid interfaces plays an important role in the dynamics of nanoscale polymer films.We investigated the influence of the interfacial chain adsorption on the glass transition temperature(Tg)and de...Polymer adsorption at solid interfaces plays an important role in the dynamics of nanoscale polymer films.We investigated the influence of the interfacial chain adsorption on the glass transition temperature(Tg)and dewetting of polystyrene(PS)thin films on a graphene substrate that has strong interaction with PS.We found that the Tgs of PS films show a non-monotonic trend with increasing amount of polymer adsorption at the interface—first increasing and then decreasing,and this change in Tg is accompanied by a wetting-dewetting transition of the PS films.Film morphological analysis showed that the PS films dewet from the interfacially adsorbed layers rather than from the substrate,i.e.,autophobic dewetting,indicating the presence of an unfavorable interaction between the adsorbed and free PS chains.We ascribed the repulsive interaction to the formation of a dense adsorbed layer on graphene due to the π-π interaction between PS and graphene,which prevents the nonadsorbed PS chain from penetrating into the adsorbed layer.This may lead to drops in Tg at high adsorption extent.展开更多
T-carbon is a new allotrope of carbon materials,and it displays high hardness and low density.Nevertheless,the hardening mechanisms of T-carbon thin films under nanoindentation remain elusive.This work utilizes molecu...T-carbon is a new allotrope of carbon materials,and it displays high hardness and low density.Nevertheless,the hardening mechanisms of T-carbon thin films under nanoindentation remain elusive.This work utilizes molecular dynamics simulation to explore the hardening mechanisms of T-carbon thin films under nanoindentation with variations of loading velocities and temperatures.The results reveal that a loading velocity increase at a given temperature raises the nanoindentation force.The increase in nanoindentation force is due to graphitization,which is related to the fracture of tetrahedral structures in T-carbon thin films.However,increased graphitization caused by an increased temperature lowers the nanoindentation force at a given loading velocity.The increased graphitization is influenced by both the fractured tetrahedrons and the deformation of inter-tetrahedron bond angles.This is attributed to the loss of thermal stability and the lower density of T-carbon thin films as the temperature increases.These findings have significant implications for the design of nanodevices for specific application requirements.展开更多
The increasingly serious electromagnetic(EM)radiation and related pollution effects have gradually attracted people's attention in the information age.Hence,it's crucial to develop adaptive shielding materials...The increasingly serious electromagnetic(EM)radiation and related pollution effects have gradually attracted people's attention in the information age.Hence,it's crucial to develop adaptive shielding materials with minimum EM waves(EMW)reflection.In this paper,Ag nanoparticles loaded mesoporous carbon hollow spheres(MCHS@Ag)were synthesized by chemical reduction method,and cellulose nanofibers(CNF)/MXene/MCHS@Ag homogeneous composites were prepared.The total EM interference shielding efficiency(SET)of CNF/MXene/MCHS@Ag composite film was 32.83 dB(at 12.4 GHz),and the absorption effectiveness(SEA)was improved to 26.6 dB,which was 63.1%and 195.5%higher than that of CNF/MXene/MCHS composite film.The low dielectric property of MCHS effectively optimized the impedance matching between the composites and air.The hollow porous structure prolonged the transmission path of EMW and increased the absorption loss of the composites.At the same time,Ag nanoparticles located the MCHS were helpful to construct the internal conductive path overcoming the damage of the conductive property caused by the low dielectric of MCHS.This research adopts a straightforward method to construct a lightweight,pliable,and mesoporous composites for EMI shielding,which serves a crucial role in the current era of severe EM pollution.展开更多
The full arrival of 5 G and advances in electronic integration make efficient heat dissipation crucial for stable operation and longer product lifespan. In this study, a vacuum-assisted filtration process was employed...The full arrival of 5 G and advances in electronic integration make efficient heat dissipation crucial for stable operation and longer product lifespan. In this study, a vacuum-assisted filtration process was employed to fabricate ammoniated alumina/MXene/bacterial cellulose (Al_(2)O_(3)-NH_(2)/MXene/BC) composite films that display a unique integration of properties, encompassing ultra-high thermal conductivity (λ), mechanical flexibility, and high photothermal conversion performance. By leveraging the bridging effect among spherical Al_(2)O_(3)-NH_(2) and MXene nanosheets, a densely packed “point-surface” structure was constructed in BC by using a one-step preparation process. When the mass fraction of Al_(2)O_(3)-NH_(2)/MXene (1:3, w/w) is 40 wt%, the O-BAl1M3 exhibited an in-plane λ of 20.02 W m^(-1) K^(-1), which was 436 % and 94 % higher than that of pure BC and T-BAl1M3 (prepared by a two-step method), respectively. Furthermore, constructing an intact thermal conductive network within BC notably promoted photothermal and photoelectric conversion performance. The maximum surface temperature and voltage of the O-BAl1M3 film reached 106.9 ℃ and 48.34 mV when a sample with an area of 1.56 cm^(2) was exposed under a light intensity of 200 mW cm^(-2). By applying O-BAl1M3 film, the temperature inside a self-built greenhouse model reached up to 64.8 ℃ within 1200 s under a light intensity of 100 mW cm^(-2), which validated the practical application of the composite films and offered a novel approach for creating flexible films with superior photothermal conversion capability. This work provided insights into preparing functional composite films for efficient thermal management and photothermal conversion applications.展开更多
Nanocrystalline alloys often exhibit unusual thermal stability as a consequence of kinetic and thermodynamic barriers to grain growth.However,the physical mechanisms governing alloy stability need to be identified.In ...Nanocrystalline alloys often exhibit unusual thermal stability as a consequence of kinetic and thermodynamic barriers to grain growth.However,the physical mechanisms governing alloy stability need to be identified.In this work,we found that grain boundary(GB)relaxation renders Ni-W alloyed films relatively stable at low annealing temperature,while twinning-mediated grain growth occurs via dislocation-GB/twin boundary(TB)interactions as the annealing temperature increases.At a relatively low temperature,TB strengthening plays a dominant role in plastic deformation,whereas precipitation strengthening gradually controls the deformation mechanism with the increase of annealing temperature.Our findings provide evidence for improving mechanical property through alloying and microstructure design,and have a crucial guiding significance in material selection and miniaturized applications such as Micro Electro Mechanical Systems.展开更多
基金supported by the Russian Science Foundation(23-29-00830).
文摘Morphology and growth rate of carbon dioxide hydrate on the interface between liquid carbon dioxide and humic acid solutions were studied in this work.It was found that after the growth of the hydrate film at the interface,further growth of hydrate due to the suction of water in the capillary system formed between the wall of the cuvette and the end boundary of the hydrate layer occurs.Most probably,substantial effects on the formation of this capillary system may be caused by variations in reactor wall properties,for example,hydrophobic-hydrophilic balance,roughness,etc.We found,that the rate of CO_(2) hydrate film growth on the surface of the humic acid aqueous solution is 4-fold to lower in comparison with the growth rate on the surface of pure water.We suppose that this is caused by the adsorption of humic acid associates on the surface of hydrate particles and,as a consequence,by the deceleration of the diffusion of dissolved carbon dioxide to the growing hydrate particle.
基金financial support of this work by the National Natural Science Foundation of China(Nos.22378332,52003219)the Open Fund of Zhejiang Key Laboratory of Flexible Electronics(No.2022FE008)+1 种基金the Natural Science Foundation of Ningbo(NO.2022J058)Ministry of Industry and Information Technology high quality development project(TC220A04A-206).
文摘Although poly(lactic acid)(PLA)is a good environmentally-friendly bio-degradable polymer which is used to substitute traditional petrochemical-based polymer packaging films,the barrier properties of PLA films are still insufficient for high-barrier packaging applications.In this study,oxygen scavenger hydroxyl-terminated polybutadiene(HTPB)and cobalt salt catalyst were incorporated into the PLA/poly(butylene adipate-co-terephthalate)(PLA/PBAT),followed by melting extrusion and three-layer co-extrusion blown film process to prepare the composite films.The oxygen permeability coefficient of the composite film combined with 6 wt%oxygen scavenger and 0.4 wt%catalyst was decreased significantly from 377.00 cc·mil·m^(-2)·day^(-1)·0.1 MPa^(-1) to 0.98 cc·mil·m^(-2)·day^(-1)·0.1 MPa^(-1),showing a remarkable enhancement of 384.69 times compared with the PLA/PBAT composite film.Meanwhile,the degradation behavior of the composite film was also accelerated,exhibiting a mass loss of nearly 60%of the original mass after seven days of degradation in an alkaline environment,whereas PLA/PBAT composite film only showed a mass loss of 32%.This work has successfully prepared PLA/PBAT composite films with simultaneously improved oxygen barrier property and degradation behavior,which has great potential for high-demanding green chemistry packaging industries,including food,agricultural,and military packaging.
基金the National Natural Science Foundation of China(22279097)the Key R&D Program of Hubei Province(2023BAB103)the PhD Scientific Research and Innovation Foundation of The Education Department of Hainan Province Joint Project of Sanya Yazhou Bay Science and Technology City(HSPHDSRF-2024-03-022)。
文摘Because of their low electrical conductivity,sluggish ion diffusion,and poor stability,conventional electrode materials are not able to meet the growing demands of energy storage and portable devices.Graphene assembled films(GAFs)formed from graphene nanosheets have an ultrahigh conductivity,a unique 2D network structure,and exceptional mechanical strength,which give them the potential to solve these problems.However,a systematic understanding of GAFs as an advanced electrode material is lacking.This review focuses on the use of GAFs in electrochemistry,providing a comprehensive analysis of their synthesis methods,surface/structural characteristics,and physical properties,and thus understand their structure-property relationships.Their advantages in batteries,supercapacitors,and electrochemical sensors are systematically evaluated,with an emphasis on their excellent electrical conductivity,ion transport kinetics,and interfacial stability.The existing problems in these devices,such as chemical inertness and mechanical brittleness,are discussed and potential solutions are proposed,including defect engineering and hybrid structures.This review should deepen our mechanistic understanding of the use of GAFs in electrochemical systems and provide actionable strategies for developing stable,high-performance electrode materials.
基金National Natural Science Foundation of China(62171208)Natural Science Foundation of Gansu Province(23JRRA1355)。
文摘ZrCoRE(RE denotes rare earth elements)non-evaporable getter films have significant applications in vacuum packaging of micro-electro mechanical system devices because of their excellent gas adsorption performance,low activation temperature and environmental friendliness.The films were deposited using DC magnetron sputtering with argon and krypton gases under various deposition pressures.The effects of sputtering gas type and pressure on the morphology and hydrogen adsorption performance of ZrCoRE films were investigated.Results show that the films prepared in Ar exhibit a relatively dense structure with fewer grain boundaries.The increase in Ar pressure results in more grain boundaries and gap structures in the films.In contrast,films deposited in Kr display a higher density of grain boundaries and cluster structures,and the films have an obvious columnar crystal structure,with numerous interfaces and gaps distributed between the columnar structures,providing more paths for gas diffusion.As Kr pressure increases,the film demonstrates more pronounced continuous columnar structure growth,accompanied by deeper and wider grain boundaries.This structural configuration provides a larger specific surface area,which significantly improves the hydrogen adsorption speed and capacity.Consequently,high Ar and Kr pressures are beneficial to improve the adsorption performance.
文摘High-quality antiferromagnetic(AFM)θ-phase manganese nitride(MnN)films were successfully grown on MgO(001)substrates by plasma-assisted molecular beam epitaxy.Structural analysis confirms the high-quality MnN film has a tetragonal distortion with a c/a ratio of~0.98.The film exhibits exceptional stability in both aqueous and ambient conditions,which is a crucial factor for practical applications.Electrical transport reveals its metallic behavior with an upturn at low temperatures,which could be attributed to the Kondo effect originated from nitrogen vacancy-induced magnetic impurities.Room temperature exchange bias has been demonstrated in a MnN/CoFeB heterostructure,verifying the AFM ordering of MnN.Considering its high Néel temperature~650 K,superior stability,and low-cost,this work highlights the epitaxial MnN films as a promising candidate for AFM spintronic applications.
基金Inner Mongolia Natural Science Foundation Project(2020LH05028)。
文摘Impact of texture type on the magnetic properties of ultrahigh density perpendicular magnetic recording media L1_(0)-FePt thin film was investigated,so were the texture formation and evolution mechanism.Reuss,Voigt,and Hill models were used to determine the anisotropic elastic modulus of L1_(0)-FePt thin film with fiber texture.Then,the elastic strain energies of thin films under various stress conditions were calculated.Results reveal that the stress condition has a significant influence on the fiber texture evolution.When the L1_(0)-FePt thin film is subjected to compressive in-plane strain prior to ordering phase transformation,the formation of{100}fiber texture is promoted.On the contrary,the ordering phase transformation under tensile in-plane strain promotes the{001}fiber texture formation.
基金supported by the National Natural Science Foundation of China (Grant Nos. 12374196, 92165201, and 11634011)the Innovation Program for Quantum Science and Technology (Grant No. 2021ZD0302800)+2 种基金the Chinese Academy of Sciences Project for Young Scientists in Basic Research (Grant No. YSBR-046)the Fundamental Research Funds for the Central Universities (Grant Nos. WK3510000006 and WK3430000003)Anhui Initiative in Quantum Information Technologies (Grant No. AHY170000)。
文摘Ising superconductivity has garnered much attention in recent years due to its extremely high in-plane upper critical field (B_(c2)).Here,we fabricated 14 multilayer Pb_(1-x)Bi_(x) (0%≤x≤40%) thin films on Si (111)-7×7 reconstructed surface by molecular beam epitaxy.Large B_(c2) beyond the Pauli limit is observed in all the Pb_(1-x)Bi_(x) films,indicating that they may exhibit characteristics of Ising superconductivity.Moreover,the introduction of Bi doping can significantly enhance and effectively tune the in-plane B_(c2) of Pb_(1-x)Bi_(x) films,which will help us better understand Ising superconductivity and provide a new platform for the development of tunable Ising superconductors.
基金funded by a research grant from the Lembaga Pengelola Dana Pendidikan-Ministry of Finance Republic of Indonesia(https://risprolpdp.kemenkeu.go.id/)(accessed on 13 September 2024)awarded under the Riset dan Inovasi untuk Indonesia Maju program with grant number 82/II.7/HK/2022.
文摘This study aimed to develop and characterize biodegradable packaging film from blends of two natural polysaccharides,i.e.,agar and glucomannan.The glucomannan used was derived from the specific tuber plant Amorphophallus oncophyllus(locally known as“porang”),which grows abundantly in Indonesian forests and remains underutilized.Various ratios of agar and porang-glucomannan(PG)proportions were formulated to produce a food packaging film,which was subsequently tested for its mechanical,physical,chemical,and thermal properties.The results showed that the inclusion of PG to the film formulations notably enhanced the stretchability of agar films,achieving maximum a twofold increase,while concurrently reducing their water resistance such as increased water solubility and water swelling for up to 125%and 105%,respectively.The mechanical and thermal properties,as well as the water vapor permeability of the resulting film,were significantly affected by the polymer matrix structure formed by the varying proportions of the two biopolymers.The enhancement of these properties was associated with a more solid/compact film structure,as corroborated by cross-sectional images obtained through SEM analysis.The study’s findings suggest that utilizing agar and porang biomass has significant potential for further development as an environmentally friendly food packaging material.
基金supported by the National Key R&D Program of China(Gran Nos.2022YFA1402304 and 2022YFA1402802)the National Natural Science Foundation of China(Grant Nos.12494591,12122405,12274169,and 92165204)+4 种基金Program for Science and Technology Innovation Team in Zhejiang(Grant No.2021R01004)Guangdong Provincial Key Laboratory of Magnetoelectric Physics and Devices(Grant No.2022B1212010008)Guangdong Fundamental Research Center for Magnetoelectric Physics(2024B0303390001)Guangdong Provincial Quantum Science Strategic Initiative(Grant No.GDZX2401010)the Fundamental Research Funds for the Central Universities。
文摘The discovery of high-temperature superconductivity in bilayer nickelate La_(3)Ni_(2)O_(7)under high-pressure conditions has spurred extensive efforts to stabilize superconductivity at ambient pressure.Recently,the realization of superconductivity in compressively strained La_(3)Ni_(2)O_(7)thin films grown on the SrLaAlO_(4)substrates,with a T_(c)exceeding 40 K,represents a significant step toward this goal.Here,we investigate the influence of film thickness and carrier doping on the electronic structure of La_(3)Ni_(2)O_(7)thin films,ranging from 0.5 to 3 unit cells,using first-principles calculations.For a 2 unit-cell film with an optimal doping concentration of 0.3 hole per formula unit(0.15 hole/Ni),the Ni-d_(z^(2))interlayer bonding state crosses the Fermi level,resulting in the formation ofγpockets at the Fermi surface.These findings align with angle-resolved photoemission spectroscopy experimental data.Our results provide theoretical validation for the recent experimental discovery of ambient-pressure superconductivity in La_(3)Ni_(2)O_(7)thin films and underscore the significant impact of film thickness and carrier doping on electronic property modulation.
基金funded by the Russian Federation represented by the Ministry of Science and Higher Education,Russia,grant number 075-15-2022-1231 on 18.10.2022National Research Foundation(NRF),South Africa,grant number 150508Brazilian National Council for Scientific and Technological Development(CNPq),Brazil,grant number 440057/2022-1.
文摘Petrochemical plastics are widely used for food protection and preservation;however,they exhibit poor biodegradability,resisting natural degradation through physical,chemical,or enzymatic processes.As a sustainable alternative to conventional plastic packaging,edible films offer effective barriers against moisture,gases,and microbial contamination while being biodegradable,biocompatible,and environmentally friendly.In this study,novel active food packaging materials(in film form)were developed by incorporating starch,carrageenan,nanocellulose(NC),Aloe vera,and hibiscus flower extract.The effects of varying the matrix composition(26.5–73.5 wt.%starch/carrageenan),NC concentration(2.77-17.07 wt.%),and particle type(fibers or crystals)on the film structure and characteristics were analyzed using various methods.Scanning electron microscopy demonstrated good homogeneity and effective dispersion of NC within the blendmatrix.An increased carrageenan content in the filmimproved wettability,moisture absorption,solubility,and water vapor permeability.The mechanical properties of the films were enhanced by NC incorporation and higher carrageenan content.The developed films also exhibited effective UV radiation barriers and biodegradability.Films with low carrageenan content(less than 33.3%)and high NC content(7%,10% crystals or 10%,15% fibers)exhibited optimal properties,including enhanced water resistance,hydrophobicity,and mechanical strength,along with reduced water vapor permeability.However,the high water solubility and moisture absorption(above 55% and 14%,respectively)indicated their unsuitability as packaging materials for food products with wet surfaces and high humidity.The results suggest that these films are well suited for use as edible food packaging for fruits and vegetables.
基金supported by the Natural Science Foundation of Shandong Province(No.ZR2023ME001),China Postdoctoral Science Foundation(No.2023M732609)the Doctoral Research Initiation Fund of Weifang University(No.2023BS01).
文摘Flexible thermoelectric thin films offer a promising avenue for the development of portable and sustainable flexible power supplies.However,a lack of thin films with excellent performance restricts their application in flexible thermoelectric devices.In this study,high-performance BiSbTe films are successfully prepared using a combination of magnetron sputtering and thermal diffusion.By optimizing carrier concentration to~4.47×10^(19)cm^(−3)and simultaneously realizing high carrier mobility of>120 cm^(2)·V^(−1)·s^(−1),an impressive room-temperature power factor of 24.13μW·cm^(−1)·K^(−2)is achieved in a Bi_(0.4)Sb_(1.6)Te_(3)thin film.The flexible Bi_(0.4)Sb_(1.6)Te_(3)thin film also demonstrates excellent bending resistance and stability(ΔR/R_(0)<5%,ΔS/S_(0)<5%,andΔS^(2)σ/S_(0)^(2)σ_(0)<10%)after 1000 bending cycles at a minimum bending radius of 6 mm.A flexible thin-film thermoelectric device assembled with p-type Bi_(0.4)Sb_(1.6)Te_(3)legs achieves a remarkable power output of~82.15 nW and a power density of~547.68μW·cm^(−2)under a temperature difference of 20 K.
基金supported by the National Key Research and Development Program of China(No.2022YFB3603101)。
文摘Polyimide(PI)is widely used in high-tech fields such as microelectronics,aerospace,and national defense because of its excellent optical properties,high-and low-temperature resistance,and good dimensional stability.To achieve the desired properties of PI,the monomers 2,6-diaminopyrimidin-4-ol(DAPD)and 6-(2,3,5,6-tetrafluoro-4-vinylphenoxy)pyrimidin-2,4-diamine(DAFPD),which contains crosslinkable functional groups,were designed and synthesized successfully and copolymerized with 4,4'-oxydianiline(ODA)and 4,4-hexafluoroisopropylphthalic anhydride(6FDA).The prepared PI film(PI-3),with rigid backbones and loose packing had excellent heat resistance(Td5%=489℃)and optical properties(T450=82%).Furthermore,a crosslinked PI film(c-PI-3)with more heat-resistant(Td5%=524℃)and better mechanical properties(σ=125.46MPa),can be obtained through thermal crosslinking of tetrafluorostyrene.In addition,the changes in the properties caused by the proportion of DAFPD added during copolymerization are discussed comprehensively.This study provides a promising candidate for heat-resistant PI materials.
基金Major Science and technology projects of Anhui Province (202103a05020003)。
文摘[Background and purposes]Proton exchange membrane fuel cells(PEMFCs),which convert hydrogen energy directly into electrical energy and water,have received overwhelming attention,owing to their potential to significantly reduce energy consumption,pollution emissions and reliance on fossil fuels.Bipolar plates are the major part and key component of PEMFCs stack,which provide mechanical strength,collect and conduct current segregate oxidants and reduce agents.They contribute 70-80%weight and 20-30%cost of a whole stack,while significantly affecting the power density.There are three types plates,including metal bipolar plate,graphite bipolar plate and composite bipolar plate.Stainless steel bipolar plates,as one of metal bipolar plate,exhibit promising manufacturability,competitive cost and durability among various metal materials.However,stainless steel would be corroded in the harsh acid(pH 2-5)and humid PEMFCs environment,whereas the leached ions will contaminate the membrane.In addition,the passivated film formed on the surface will increase the interfacial contact resistance(ICR).In order to improve the corrosion resistance and electrical conductivity of steel bipolar plates,surface coatings are essential.Metal nitride coatings,metal carbide coatings,polymer coatings and carbon-based coatings have been introduced in recent years.Carbon-based coatings,mainly including a-C(amorphous Carbon),Ta-C(Tetrahedral amorphous carbon)and DLC(diamond-like carbon),have attracted considerable attention from both academia and industry,owing to their superior performance,such as chemical inertness,mechanical hardness and electrical conductivity.However,Ta-C films as protective coating of PEMFCs have been rarely reported,due to the difficulty in production for industrial application.In this paper,multi-layer Ta-C composite films were produced by using customized industrial-scale vacuum equipment to address those issues.[Methods]Multiple layered Ta-C coatings were prepared by using PIS624 equipment,which assembled filtered cathodic arc evaporation,ion beam and magnetron sputtering into one equipment,while SS304 and silicon specimens were used as substrate for testing and analysis.Adhesion layer and intermediate layer were deposited by using magnetron sputtering at deposition temperature of 150℃and pressure of 3×10^(−1) Pa,while the sputtering current was set to be 5 A and bias power to be 300 V.The Ta-C layer was coated at arc current of 80-100 A,bias voltage of 1500 V and gas flow of 75 sccm.A scanning electron microscope(CIQTEK SEM3200)was used to characterize surface morphology,coating structure and cross-section profile of the coatings.Raman spectrometer(LabRam HR Evolution,HORIBA JOBIN YVON)was used to identify the bonding valence states.Electrochemical tests were performed by using an electrochemical work station(CHI760,Shanghai Chenhua Instrument Co.,Ltd.),with the traditional three electrode system,where saturated Ag/AgCl and platinum mesh were used as the reference electrode and counter electrode,respectively.All samples were mounted in plastic tube and sealed with epoxy resin,with an exposure area of 2.25 cm^(2),serving as the working electrode.Electrochemical measurements were carried out in simulated PEMFCs cathode environment in 0.5 mol·L^(−1) H_(2)SO_(4)+5 ppm F−solution,at operating temperature of 70℃.As the cathode environment was harsher than the anode environment,all the samples are stabilized at the open-circuit potential(OCP)for approximately 30 min before the EIS measurements.ICR between bipolar plates and GDL was a key parameter affecting performance of the PEMFCs stack.The test sample sandwiched between 2 pieces of carbon paper(simulate gas diffusion layer,GDL)was placed between 2 gold-plated copper electrodes at a compaction pressure of 1.4 MPa,which was considered to be the conventional compaction pressure in the PEMFCs.Under the same conditions,the resistance of a single carbon paper was measured as well.The ICR was calculated according to the formula ICR=1/2(R2−R1)×S,where S was the contact area between GDL and coated stainless steel BPPs.All data of ICR were measured three times for averaging.[Results]The coatings deposited by filtered cathodic arc technology were compact and smooth,which reduced coating porosity and favorable to corrosion resistance.The coating thickness of adhesion and intermediate layers were 180 nm,while the protective Ta-C coating thickness was about 300 nm,forming multiple coating to provide stronger protection for metal bipolar plates.Cr,Ti,Nb and Ta coatings were selected as adhesion layers for comparison.According to electrochemical test,Ta and Nb coatings have higher corrosion resistance.However,Ta and Nb materials would be costly when they are used for mass production.Relatively,Cr and Ti materials were cost effective.Hence,a comprehensive assessment was indispensable to decide the materials to be selected as adhesion layer.Ta-TiN and Ti-TiN combined adhesion and intermediate layer exhibited stronger corrosion resistance,with the corrosion current to be less than 10^(−6) A·cm^(−2).Ta-C protective coating deposited by using filtered cathodic arc technology indicated displayed higher corrosion resistance,with the average corrosion density to be about 1.26×10^(−7) A·cm^(−2).Ta-C coating also shown larger contact angle,with the highest hydrophobicity,which was one of the important advantages for Ta-C,in terms of corrosion resistance.According to Raman spectroscopy,the I(D)/I(G)=549.8/1126.7=0.487,with the estimated fraction of sp^(3) bonding to be in the range of 5154%.The intermediate layer TiN has higher conductivity than the CrN layer.Considering cost,corrosion performance and ICR result,the Ti-TiN layer combination is recommended for industrial scale application.[Conclusions]Multiple layer coating structure of Ta-C film had stronger corrosion resistance;with more than 50%sp^(3) content,while it also had larger water contact angle and higher corrosion resistance than DLC film.The filtered arcing deposition technology was able to make the film to be more consistent and stable than normal arcing technology in terms of the preparation of Ta-C.The coating displayed corrosion density of 1.26×10^(−7) A·cm^(−2) and ICR of less than 5 mΩ·cm^(2),far beyond technical target of 2025 DOE(US Department of Energy).This indicated that the mass-production scale coating technology for PEMFC bipolar plates is highly possible.
基金the National Natural Science Foundation of China(Nos.U2032101 and 11905306)the National Key Research and Development Project of China(No.2022YFB2402602).
文摘The early stages of crystallization and occurrence of surface wrinkling were investigated using poly(butadiene)-block-poly(ε-caprolactone)with an ordered lamellar structure.Direct evidence has demonstrated that surface wrinkling precedes nucleation and crystal growth.This study examined the relationship between surface wrinkling,nucleation,and the formation of crystalline supramolecular structures using atomic force microscopy(AFM)and X-ray scattering measurements.Surface wrinkling is attributed to curving induced by accumulated stresses,including residual stress from the sample preparation and thermal stress during cooling.These stresses cause large-scale material flow and corresponding changes in the molecular conformations,potentially reducing the nucleation barrier.This hypothesis is supported by the rapid crystal growth observed following the spread of surface wrinkles.Additionally,the surface curving of the polymer thin film creates local minima of the free energy,facilitating nucleation.The nuclei subsequently grow into crystalline supramolecular structures by incorporating polymer molecules from the melt.This mechanism highlights the role of localized structural inhomogeneity in the early stages of crystallization and provides new insights into structure formation processes.
基金funded by the Agricultural Science and Technology Innovation Fund of Jiangsu Province[Grant/Award Number:CX(24)1008]Key Research and Development Program Project of Henan Province(251111110100)National State Science Foundation of China[Grant/Award Number:21808093].
文摘Long-time fermentation has always been one of the reasons restricting the development of straw biological pulping.This study aimed to develop a novel straw pulp film with shortened solid-state fermentation time with less than 20%mass loss rate by bio-pulping synergistic treatment of straw fibers with deep eutectic solvent(DES)and Streptomyces rochei(S.rochei).Results illustrated that at 3%S.rochei concentration with 7-day fermentation,both cellulose and hemicellulose enzyme activities of the treated rice straw fiber reached peak values with a fiber mass loss rate of 17.01%.Microstructural morphology revealed that S.rochei colonization initiated on straw surfaces and progressively penetrated internal structures,resulting in surface loosening and distinct disruption of cell wall tissues within vascular bundles in transverse sections.The treated rice straw strip indicated a maximum tensile strength of 46.22 MPa for(Bacteria)BA 3%at day 7,attributed to optimized synergistic effects of microfibril angle(MFA)and cellulose/hemicellulose relative content ratio.The modified straw pulp film exhibited significant enhancement in the tensile index(44.9%increase),burst index(10.3%increase),and tear index(60%increase)compared to untreated groups.This work demonstrated the important role ofDES and S.rochei bio-pulping synergistic treatment in improving rice straw pulp performance,suggesting an eco-friendly,novel,and efficient biomass pretreatment technology for potential application prospects in sustainable agricultural mulching materials.
基金supported by the National Natural Science Foundation of China(Nos.22122306,22303084 and 52373025)。
文摘Polymer adsorption at solid interfaces plays an important role in the dynamics of nanoscale polymer films.We investigated the influence of the interfacial chain adsorption on the glass transition temperature(Tg)and dewetting of polystyrene(PS)thin films on a graphene substrate that has strong interaction with PS.We found that the Tgs of PS films show a non-monotonic trend with increasing amount of polymer adsorption at the interface—first increasing and then decreasing,and this change in Tg is accompanied by a wetting-dewetting transition of the PS films.Film morphological analysis showed that the PS films dewet from the interfacially adsorbed layers rather than from the substrate,i.e.,autophobic dewetting,indicating the presence of an unfavorable interaction between the adsorbed and free PS chains.We ascribed the repulsive interaction to the formation of a dense adsorbed layer on graphene due to the π-π interaction between PS and graphene,which prevents the nonadsorbed PS chain from penetrating into the adsorbed layer.This may lead to drops in Tg at high adsorption extent.
文摘T-carbon is a new allotrope of carbon materials,and it displays high hardness and low density.Nevertheless,the hardening mechanisms of T-carbon thin films under nanoindentation remain elusive.This work utilizes molecular dynamics simulation to explore the hardening mechanisms of T-carbon thin films under nanoindentation with variations of loading velocities and temperatures.The results reveal that a loading velocity increase at a given temperature raises the nanoindentation force.The increase in nanoindentation force is due to graphitization,which is related to the fracture of tetrahedral structures in T-carbon thin films.However,increased graphitization caused by an increased temperature lowers the nanoindentation force at a given loading velocity.The increased graphitization is influenced by both the fractured tetrahedrons and the deformation of inter-tetrahedron bond angles.This is attributed to the loss of thermal stability and the lower density of T-carbon thin films as the temperature increases.These findings have significant implications for the design of nanodevices for specific application requirements.
基金supported by the National Natural Science Foundation of China(grant no.52273044,52373092)the Opening Project of State Key Laboratory of Polymer Materials Engineering(Sichuan University)(grant no.sklpme2023-3-4)+1 种基金the Key Research Program of Zhejiang Province(grant no.2023C01101,2023C01210,2022C01049,2022C01205)the Natural Science Foundation of Zhejiang Province(grant no.LY20E030008).
文摘The increasingly serious electromagnetic(EM)radiation and related pollution effects have gradually attracted people's attention in the information age.Hence,it's crucial to develop adaptive shielding materials with minimum EM waves(EMW)reflection.In this paper,Ag nanoparticles loaded mesoporous carbon hollow spheres(MCHS@Ag)were synthesized by chemical reduction method,and cellulose nanofibers(CNF)/MXene/MCHS@Ag homogeneous composites were prepared.The total EM interference shielding efficiency(SET)of CNF/MXene/MCHS@Ag composite film was 32.83 dB(at 12.4 GHz),and the absorption effectiveness(SEA)was improved to 26.6 dB,which was 63.1%and 195.5%higher than that of CNF/MXene/MCHS composite film.The low dielectric property of MCHS effectively optimized the impedance matching between the composites and air.The hollow porous structure prolonged the transmission path of EMW and increased the absorption loss of the composites.At the same time,Ag nanoparticles located the MCHS were helpful to construct the internal conductive path overcoming the damage of the conductive property caused by the low dielectric of MCHS.This research adopts a straightforward method to construct a lightweight,pliable,and mesoporous composites for EMI shielding,which serves a crucial role in the current era of severe EM pollution.
基金support of this work by the Project of Education Department of Shaanxi Province(No.23JK0373)the Shaanxi University of Technology Graduate Innovation Fund(No.SLGYCX2402)the Talent Start-up Fund of Shaanxi University of Technology(No.SLGRCQD2329).
文摘The full arrival of 5 G and advances in electronic integration make efficient heat dissipation crucial for stable operation and longer product lifespan. In this study, a vacuum-assisted filtration process was employed to fabricate ammoniated alumina/MXene/bacterial cellulose (Al_(2)O_(3)-NH_(2)/MXene/BC) composite films that display a unique integration of properties, encompassing ultra-high thermal conductivity (λ), mechanical flexibility, and high photothermal conversion performance. By leveraging the bridging effect among spherical Al_(2)O_(3)-NH_(2) and MXene nanosheets, a densely packed “point-surface” structure was constructed in BC by using a one-step preparation process. When the mass fraction of Al_(2)O_(3)-NH_(2)/MXene (1:3, w/w) is 40 wt%, the O-BAl1M3 exhibited an in-plane λ of 20.02 W m^(-1) K^(-1), which was 436 % and 94 % higher than that of pure BC and T-BAl1M3 (prepared by a two-step method), respectively. Furthermore, constructing an intact thermal conductive network within BC notably promoted photothermal and photoelectric conversion performance. The maximum surface temperature and voltage of the O-BAl1M3 film reached 106.9 ℃ and 48.34 mV when a sample with an area of 1.56 cm^(2) was exposed under a light intensity of 200 mW cm^(-2). By applying O-BAl1M3 film, the temperature inside a self-built greenhouse model reached up to 64.8 ℃ within 1200 s under a light intensity of 100 mW cm^(-2), which validated the practical application of the composite films and offered a novel approach for creating flexible films with superior photothermal conversion capability. This work provided insights into preparing functional composite films for efficient thermal management and photothermal conversion applications.
基金supported by the National Natural Science Foundation of China(Grant Nos.92163201,52431006,52441407,U23A6013,92360301 and U2330203)the Shaanxi Province Innovation Team Project(2024RS-CXTD-58)+2 种基金the Shaanxi Province Youth Innovation Team Project(22JP042)the Natural Science Basic Research Plan in Shaanxi Province(2022JQ-460)the Fundamental Research Funds for the Central Universities(xtr062024006,xtr022019004 and xzy022022024).
文摘Nanocrystalline alloys often exhibit unusual thermal stability as a consequence of kinetic and thermodynamic barriers to grain growth.However,the physical mechanisms governing alloy stability need to be identified.In this work,we found that grain boundary(GB)relaxation renders Ni-W alloyed films relatively stable at low annealing temperature,while twinning-mediated grain growth occurs via dislocation-GB/twin boundary(TB)interactions as the annealing temperature increases.At a relatively low temperature,TB strengthening plays a dominant role in plastic deformation,whereas precipitation strengthening gradually controls the deformation mechanism with the increase of annealing temperature.Our findings provide evidence for improving mechanical property through alloying and microstructure design,and have a crucial guiding significance in material selection and miniaturized applications such as Micro Electro Mechanical Systems.
