Silicon(Si)has gained popularity as a potential anodic material for Li-ion batteries(LIBs)due to its large theoretical capacity.However,low conductivity,large volume expansion,and side reactions during alloying and de...Silicon(Si)has gained popularity as a potential anodic material for Li-ion batteries(LIBs)due to its large theoretical capacity.However,low conductivity,large volume expansion,and side reactions during alloying and de-alloying lead to poor cyclic and bad high-rate performance,which has severely hindered its practical large-scale application.Herein,a novel stamen-structured Si-based anode material with a protective SiO_(x)layer and dual carbon layers(Si@SiO_(x)/C@C)is designed for high-performance LIBs.The protective SiO_(x)layer reduces side reactions and dual carbon layers enhance charge transport to improve reaction kinetics,while the unique structure provides buffering space for volume expansion.Such Si@SiO_(x)/C@C anode demonstrates impressive Li storage properties for a half-battery,including a discharge capacity of 2935 mA h g^(-1)at a current density 0.1 A g^(-1),cyclic performance(814 mA h g^(-1)at 2 A g^(-1)over 500 cycles and 988 mA h g^(-1)over 200 cycles at 1 A g^(-1))and a rate performance(609 mA h g^(-1)at 5 A g^(-1)).It also maintains a high reversible capacity of 131 mA h g^(-1)at 0.25 C after100 cycles for a full battery.This work provides insights into the novel design of multiple protective layers on Si-based anode materials for fast-charging and highly stable LIBs.展开更多
Among the many strategies to fabricate the silicon/carbon composite,yolk/double-shells structure can be regarded as an effective strategy to overcome the intrinsic defects of Si-based anode materials for Li-ion batter...Among the many strategies to fabricate the silicon/carbon composite,yolk/double-shells structure can be regarded as an effective strategy to overcome the intrinsic defects of Si-based anode materials for Li-ion batteries(LIBs).Hereon,a facile and inexpensive technology to prepare silicon/carbon composite with yolk/double-shells structure is proposed,in which the double buffering carbon shells are fabricated.The silicon/carbon nanoparticles with core-shell structure are encapsulated by SiO_(2)and external carbon layer,and it shows the yolk/double-shells structure via etching the SiO_(2)sacrificial layer.The multiply shells structure not only significantly improves the electrical conductivity of composite,but also effectively prevents the exposure of Si particles from the electrolyte composition.Meanwhile,the yolk/double-shells structure can provide enough space to accommodate the volume change of the electrode during charge/discharge process and avoid the pulverization of Si particles.Moreover,the as-prepared YDS-Si/C shows excellent performance as anode of LIBs,the reversible capacity is as high as 1066 mA h g^(-1) at the current density of 0.5 A g^(-1) after 200 cycles.At the same time,the YDS-Si/C has high capacity retention and good cyclic stability.Therefore,the unique architecture design of yolk/double-shells for Si/C composite provides an instructive exploration for the development of next generation anode materials of LIBs with high electrochemical performances and structural stability.展开更多
In this work, a series of Pt nanocrystallines（Pt NCs） supported on TiO2 substrate with controlled thickness of carbon layers（C-Pt/TiO2） were synthesized. Well-dispersed Pt NCs were facilely synthesized at room tem...In this work, a series of Pt nanocrystallines（Pt NCs） supported on TiO2 substrate with controlled thickness of carbon layers（C-Pt/TiO2） were synthesized. Well-dispersed Pt NCs were facilely synthesized at room temperature by a photo-reduction process in lytropic liquid crystal（LCs）. Surface tuning of the carbon layers on Pt/TiO2 catalysts was achieved by varying the calcination atmospheres（in argon, air, and oxygen） and characterized by XPS and HRTEM. The influence of the coated carbon layers on the catalytic activity of catalysts is investigated by CO oxidation reaction which presented the following ranks： C-Pt/TiO2-O2〉 C-Pt/TiO2-Air 〉 C-Pt/TiO2-Ar. It is found that the carbon layer coating can stabilize the Pt NCs and enable them anti-sintering at high temperature. This finding provides new insight into understanding the C-Pt/TiO2 ternary system for tuning their catalytic performance.展开更多
Polyacrylonitrile-based commercial carbon fibers(CFs)have garnered significant attention in mechanical applications because of their exceptional mechanical properties.However,their functional versatility relies heavil...Polyacrylonitrile-based commercial carbon fibers(CFs)have garnered significant attention in mechanical applications because of their exceptional mechanical properties.However,their functional versatility relies heavily on the structural intricacies of duplex carbon layers.Current modification approaches,though effective,are encumbered by complexity and cost,limiting widespread adoption across diverse fields.We herein present a straightforward modification strategy centered on regulating carbon layers to unlock the multifunctional potential of CFs.Our method leverages two common anions,Cl^(-)and SO_(4)^(2-),to facilitate oxidation reactions in CFs under robust alkali and high voltage conditions.Cl^(-)effectively activates carbon layers,while SO_(4)^(2-)facilitates layer movement.The electrocatalytic activities of the resultant CFs are enhanced,with state-of-the-art performance as supercapacitors and exceptional stability.Moreover,our approach achieves a groundbreaking milestone by bending and fusing CFs without using binders.This breakthrough can reduce the manufacturing costs of CF-based products.It also facilitates the development of novel microelectronic devices.展开更多
Aqueous zinc metal batteries(ZMBs)which are environmentally benign and cheap can be used for grid-scale energy storage,but have a short cycling life mainly due to the poor reversibility of zinc metal anodes in mild aq...Aqueous zinc metal batteries(ZMBs)which are environmentally benign and cheap can be used for grid-scale energy storage,but have a short cycling life mainly due to the poor reversibility of zinc metal anodes in mild aqueous electrolytes.A zincophilic carbon(ZC)layer was deposited on a Zn metal foil at 450°C by the up-stream pyrolysis of a hydrogen-bonded supramolecular substance framework,as-sembled from melamine(ME)and cyanuric acid(CA).The zincophilic groups(C=O and C=N)in the ZC layer guide uniform zinc plating/stripping and eliminate dendrites and side reactions.so that assembled symmetrical batteries(ZC@Zn//ZC@Zn)have a long-term service life of 2500 h at 1 mA cm^(−2) and 1 mAh cm^(−2),which is much longer than that of bare Zn anodes(180 h).In addition,ZC@Zn//V2O5 full batteries have a higher capacity of 174 mAh g^(−1) after 1200 cycles at 2 A g^(−1) than a Zn//V_(2)O_(5) counterpart(100 mAh g^(−1)).The strategy developed for the low-temperat-ure deposition of the ZC layer is a new way to construct advanced zinc metal anodes for ZMBs.展开更多
Zinc-ion battery(ZIB)has been regarded as one of the most promising sustainable energy storage systems due to its low cost,safety,and attractive electrochemical performance.However,the metallic zinc anode with uneven ...Zinc-ion battery(ZIB)has been regarded as one of the most promising sustainable energy storage systems due to its low cost,safety,and attractive electrochemical performance.However,the metallic zinc anode with uneven deposition during cycling would result in significant capacity decay,low Coulombic efficiency,and electrolyte consumption,thus the undesirable cyclability severely hampers the practical applications.Herein,a phosphorus-doped carbon protective layer was coated onto the surface of Zn anode via using the plasma-enhanced chemical vapor deposition(PECVD)approach.Enhanced conductivity and lower nucleation overpotential induced by the P-doped carbon protective layer can effectively facilitate the ion diffusion kinetics and suppress side reactions.The as-fabricated P-C/Zn anode demonstrated excellent cycling stability during the zinc plating/stripping process,maintaining a low voltage hysteresis(34.8 m V)for over 1000 h under a current density of 2 m A/cm^(2)and a capacity of 2 m Ah/cm^(2).Moreover,the P-C/Zn||MnO_(2)full cell exhibited high specific capacity of about 252.5 m Ah/g at 2 A/g upon 700 long cycles.This study is helpful to design more efficient zinc-ion batteries towards the future applications.展开更多
The proliferation of advanced electronics and devices has led to significant electromagnetic interference and pollution,resulting in heightened interest in electromagnetic interference(EMI)shielding materials in recen...The proliferation of advanced electronics and devices has led to significant electromagnetic interference and pollution,resulting in heightened interest in electromagnetic interference(EMI)shielding materials in recent years.Carbon foam,as a typical porous carbonaceous material,demonstrates significant potential as an innovative EMI shielding material owing to its lightweight nature,exceptional porosity,flexibility,favorable processability,and environmental sustainability.Nonetheless,the configuration of carbon atoms within the carbon foam is significantly disordered,leading to its intrinsic conductivity being comparatively low.Consequently,its shielding efficacy cannot meet the standards required for commercial EMI materials.Herein,we propose a hierarchical engineering strategy to construct a carbon foam composite with high shielding efficacy.Specifically,the FeCo nanoparticles and carbon layer are concurrently integrated into the carbon foam matrix to modulate its magnetic characteristics and conductivity.The results demonstrate that the carbon-coated FeCo/carbon foam composite achieves a shielding effectiveness(SE)of 24 dB in the X-band,signifying a 240% improvement compared to the pristine carbon foam.Simultaneously,the composite also exhibits superior multifunctionalities involving flexibility,Joule heating,and hydrophobicity.This study provides a facile and effective routine to regulate the shielding efficacy of EMI shielding materials.展开更多
In-situ observation of the charge transfer plays a key role in understanding the working mechanism of hematite for solar water oxidation.Here by using in-situ X-ray absorption spectroscopy(XAS),the electron injection ...In-situ observation of the charge transfer plays a key role in understanding the working mechanism of hematite for solar water oxidation.Here by using in-situ X-ray absorption spectroscopy(XAS),the electron injection from illuminated hematite(photon-excited electron)to the surface carbon layer can be clearly identified,which can facilitate the charge separation and then improve the performance.As a result,the carbon-coated and Sn-doped hematite photoanode(C-Sn-Fe_(2)O_(3))shows a greatly enhanced photocurrent density of 2.3 mA/cm^(2) at 1.23 VRHE,which is 2.3 times that of the pristine hematite.The injected electron can modify the chemical state of surface groups in the carbon layer and be quickly transferred to the electrode due to the high conductivity of the carbon layer,leaving behind the high-valence Fe^(4+)with high oxidation capability to enhance the performance.By coupling with the FeNiOOH co-catalyst,the photoanode can finally achieve a high photocurrent density of 3.0 mA/cm^(2) at 1.23 VRHE with a low onset potential of 0.76 VRHE.The understanding of the charge migration route by using in-situ XAS offers a novel way for the design of highly efficient solar water oxidation materials.展开更多
Although room-temperature superconductivity is still difficult to achieve,researching materials with electrical conductivity significantly higher than that of copper will be of great importance in improving energy eff...Although room-temperature superconductivity is still difficult to achieve,researching materials with electrical conductivity significantly higher than that of copper will be of great importance in improving energy efficiency,reducing costs,lightening equipment weight,and enhancing overall performance.Herein,this study presents a novel copper-carbon nanofilm composite with enhanced conductivity which has great applications in the electronic devices and electrical equipment.Multilayer copper-carbon nanofilms and interfaces with superior electronic structures are formed based on copper materials using plasma immersion nanocarbon layer deposition technology,effectively enhancing conductivity.Experimental results show that for a five-layer copper-carbon nanofilm composite,the conductivity improves significantly when the thickness of the carbon nanofilm increases.When the carbon nanofilm accounts for 16%of the total thickness,the overall conductivity increases up to 30.20%compared to pure copper.The mechanism of the enhanced conductivity is analyzed including roles of copper atom adsorption sites and electron migration pathways by applying effective medium theory,first-principles calculations and density of states analysis.Under an applied electric field,the high-density electrons in the copper film can migrate into the nanocarbon film,forming highly efficient electron transport channels,which significantly enhance the material’s conductivity.Finally,large-area electrode coating equipment is developed based on this study,providing the novel and robust strategy to enhance the conductivity of copper materials,which enables industrial application of copper-carbon nanocomposite films in the field of high conductivity materials.展开更多
A key property of the boreal forest is that it stores huge amounts of carbon(C),especially belowground in the soil.Amounts of C stored in the uppermost organic layer of boreal forest soils vary greatly in space due to...A key property of the boreal forest is that it stores huge amounts of carbon(C),especially belowground in the soil.Amounts of C stored in the uppermost organic layer of boreal forest soils vary greatly in space due to an interplay between several variables facilitating or preventing C accumulation.In this study,we split C stocks into the organic layer and charcoal C due to their difference in origin,stability,and ecological properties.We compared organic layer C and charcoal C stocks in two regions of south-central Norway(Trillemarka and Varaldskogen),characterized by Scots pine and Norway spruce forests with varying fire histories.We used structural equation modeling to investigate how vegetation composition,hydrotopography,and soil properties interplay to shape organic layer C and charcoal C stocks.Pine forests consistently contained larger organic layer C stocks than spruce forests.Charcoal stocks,in contrast,were less consistent across both forest types and study regions as pine forests had higher charcoal C stocks than spruce forests in Trillemarka,while the two forest types contained equal charcoal C stocks in Varaldskogen.Charcoal and soil organic layer C stocks increased with higher fire frequencies(number of fire events over the last 600 years),but not with a shorter time since last fire(TSF).Additionally,vegetation composition,terrain slope,and soil moisture were the most important drivers of the organic layer C stocks,while charcoal C stocks were mainly controlled by the depth of the organic layer.Also,microtopography was of importance for organic layer C and charcoal C,since depressions in the forest floor had more charcoal C than well-drained minor hills.展开更多
Photogenerated charge separation is a challenging step in semiconductor-based photosynthesis.Though numerous efforts have been devoted to developing multi-component photocatalyst heterostructures for improving charge ...Photogenerated charge separation is a challenging step in semiconductor-based photosynthesis.Though numerous efforts have been devoted to developing multi-component photocatalyst heterostructures for improving charge separation efficiency,the short distance between electrons and holes-aggregated regions still leads to undesirable charge recombination.Herein,a facile and commercial in-situ synthesis method was designed to directly prepare a three-component Au–carbon–TiO_(2)photocatalyst from Ti_(3)C_(2)MXene,air,CO_(2),and HAuCl_(4),in which the carbon layer bridged Au and TiO_(2)nanoparticles for stable and efficient photocatalytic hydrogen production.Kelvin probe measurements and density functional theory(DFT)calculations demonstrated that a multi-interfacial charge transmission network was successfully constructed to achieve a directional and long-distance spatial charge separation/transfer channel between TiO_(2)and Au through carbon layer,desirably inhibiting the recombination of photogenerated charge carriers.The hydrogen production rate of the formed three-component Au/C–TiO_(2)(CTA)photocatalyst was demonstrated to be 27 times higher than that of Au–TiO_(2),which also surpassed many reported Ti_(3)C_(2)MXene-derived carbon–TiO_(2)photocatalysts.This work sheds light on the ingenious use of 2D MXene to form a well-behaved TiO_(2)-based photocatalytic system and helps to propose future design principles in accelerating charge transfer.展开更多
Converting sunlight directly to fuels and chemicals is a great latent capacity for storing renewable energy.Due to the advantages of large surface area,short diffusion paths for electrons,and more exposed active sites...Converting sunlight directly to fuels and chemicals is a great latent capacity for storing renewable energy.Due to the advantages of large surface area,short diffusion paths for electrons,and more exposed active sites,few‐layer carbon nitride(FLCN)materials present great potential for production of solar fuels and chemicals and set off a new wave of research in the last few years.Herein,the recent progress in synthesis and regulation of FLCN‐based photocatalysts,and their applications in the conversion of sunlight into fuels and chemicals,is summarized.More importantly,the regulation strategies from chemical modification to microstructure control toward the production of solar fuels and chemicals has been deeply analyzed,aiming to inspire critical thinking about the effective approaches for photocatalyst modification rather than developing new materials.At the end,the key scientific challenges and some future trend of FLCN‐based materials as advanced photocatalysts are also discussed.展开更多
Due to the increasingly depleted limited fossil fuel resources,the development of renewable energy is the key to promote sustainable development which is an important part of the energy strategy[1].NH3 is one of most ...Due to the increasingly depleted limited fossil fuel resources,the development of renewable energy is the key to promote sustainable development which is an important part of the energy strategy[1].NH3 is one of most important and largest chemical productions in the world,it can be used as a feedstock for nitrogen fertilizer productions[2,3]or as a carbon-free energy carrier[4,5].展开更多
Lithium-ion capacitors(LICs) of achieving high power and energy density have garnered significant attention. However, the kinetics unbalance between anode and cathode can impede the application of LICs. Vanadium nitri...Lithium-ion capacitors(LICs) of achieving high power and energy density have garnered significant attention. However, the kinetics unbalance between anode and cathode can impede the application of LICs. Vanadium nitride(VN) with a high theoretical specific capacity(~ 1200 m Ah·g^(-1)) is a better pseudocapacitive anode to match the response of cathode in LICs. However, the insertion/extraction of Li-ions in VN's operation results in significant volume expansion. Herein, the VN/N-r GO-5composite that three-dimentional(3D) dicyandiamidederived-carbon(DDC) tightly wrapped VN quantum dots(VN QDTs) on two-dimentional(2D) reduced graphene oxid(r GO) was prepared by a facile strategy. The VN QDTs can reduce ion diffusion length and improve charge transfer kinetics. The 2D r GO as a template provides support for nanoparticle dispersion and improves electrical conductivity. The 3D DDC tightly encapsulated with VN QDTs mitigates agglomeration of VN particles as well as volume expansion. Correspondingly, the LICs with VN/Nr GO-5 composite as anode and activated carbon(AC) as cathode were fabricated, which exhibits a high energy density and power density. Such strategy provides a perspective for improving the electrochemical properties of LIC anode materials by suppressing volume expansion and enhancing conductivity.展开更多
An extensive study has been conducted on the proton exchange membrane fuel cells （PEMFCs） with reducing Pt loading. This is commonly achieved by developing methods to increase the utilization of the platinum in the ...An extensive study has been conducted on the proton exchange membrane fuel cells （PEMFCs） with reducing Pt loading. This is commonly achieved by developing methods to increase the utilization of the platinum in the catalyst layer of the electrodes. In this paper, a novel process of the catalyst layers was introduced and investigated. A mixture of carbon powder and Nafion solution was sprayed on the glassy carbon electrode （GCE） to form a thin carbon layer. Then Pt particles were deposited on the surface by reducing hexachloroplatinic （IV） acid hexahydrate with methanoic acid. SEM images showed a continuous Pt gradient profile among the thickness direction of the catalytic layer by the novel method. The Pt nanowires grown are in the size of 3 nm （diameter） x l0 nm （length） by high solution TEM image. The novel catalyst layer was characterized by cyclic voltammetry （CV） and scanning electron microscope （SEM） as compared with commercial Pt/C black and Pt catalyst layer obtained from sputtering. The results showed that the platinum nanoparticles deposited on the carbon powder were highly utilized as they directly faced the gas diffusion layer and offered easy access to reactants （oxygen or hydrogen）.展开更多
Relatively well crystallized and high aspect ratio Mg-Al layered double hydroxides（LDHs） were prepared by coprecipitation process in aqueous solution and further rehydrated to an organic modified LDH（OLDH） in the ...Relatively well crystallized and high aspect ratio Mg-Al layered double hydroxides（LDHs） were prepared by coprecipitation process in aqueous solution and further rehydrated to an organic modified LDH（OLDH） in the presence of surfactant. The intercalated structure and high aspect ratio of OLDH were verified by X-ray diffraction（XRD） and scanning electron microscopy（SEM）. A series of poly（propylene carbonate）（PPC）/OLDH composite films with different contents of OLDH were prepared via a melt-blending method. Their cross section morphologies, gas barrier properties and tensile strength were investigated as a function of OLDH contents. SEM results show that OLDH platelets are well dispersed within the composites and oriented parallel to the composite sheet plane. The gas barrier properties and tensile strength are obviously enhanced upon the incorporation of OLDH. Particularly, PPC/2%OLDH film exhibits the best barrier properties among all the composite films. Compared with pure PPC, the oxygen permeability coefficient（OP） and water vapor permeability coefficient（WVP） is reduced by 54% and 17% respectively with 2% OLDH addition. Furthermore, the tensile strength of PPC/2%OLDH is 83% higher than that of pure PPC with only small lose of elongation at break. Therefore, PPC/OLDH composite films show great potential application in packaging materials due to its biodegradable properties, superior oxygen and moisture barrier characteristics.展开更多
Composite made of short-cut carbon fiber mat and vinyl ester resin was observed to be an effective sensor for tensile strain up to 6 000με. Based on its strain sensitivity, a skin-like sensitive layer which can cont...Composite made of short-cut carbon fiber mat and vinyl ester resin was observed to be an effective sensor for tensile strain up to 6 000με. Based on its strain sensitivity, a skin-like sensitive layer which can continuously cover the structural surface to sense strain in large area was developed. The sensitive layer was applied to continuously monitor the deformation of a simply supported beam. The result indicates that the fractional change in electrical resistance of the sensitive layer reversibly reflects the beam deformation in each section and describes the distribution of the average strain of the beam. The effect of temperature change on the monitoring was studied by monitoring tests conducted at different temperatures ranging from 20 to 80 ℃, which reveals temperature sensitivity in the sensitive layer and the temperature dependence of the piezoresistive behavior when the temperature exceeds 50 ℃. By the application of differential conaection principle, a method for temperature compensation was established and the gauge factor for the monitoring was dramatically increased. This method was verified experimentally.展开更多
To extend the application of carbon nanotubes （CNTs） and explore novel aluminum matrix composites,CNTs were coated by molybdenum layers using metal organic chemical vapor deposition,and then Mo-coated CNT （Mo-CNT）...To extend the application of carbon nanotubes （CNTs） and explore novel aluminum matrix composites,CNTs were coated by molybdenum layers using metal organic chemical vapor deposition,and then Mo-coated CNT （Mo-CNT）/Al composites were prepared by the combination processes of powder mixing and spark plasma sintering.The influences of powder mixing and Mo-CNT content on the mechanical properties and electrical conductivity of the composites were investigated.The results show that magnetic stirring is better than mechanical milling for mixing the Mo-CNTs and Al powders.The electrical conductivity of the composites decreases with increasing Mo-CNT content.When the Mo-CNT content is 0.5wt%,the tensile strength and hardness of Mo-CNT/Al reach their maximum values.The tensile strength of 0.5wt% Mo-CNT/Al increases by 29.9%,while the electrical conductivity only decreases by 7.1%,relative to sintered pure Al.The phase analysis of Mo-CNT/Al composites reveals that there is no formation of Al carbide in the composites.展开更多
We investigated the thickness effect on the photophysics and charge carrier kinetics of graphitic carbon nitride nanoflakes （g-CNN） by using ultraviolet visible diffuse reflectance spectroscopy, atomic force microsc...We investigated the thickness effect on the photophysics and charge carrier kinetics of graphitic carbon nitride nanoflakes （g-CNN） by using ultraviolet visible diffuse reflectance spectroscopy, atomic force microscopy, femtosecond transient absorption spectroscopy, and picosecond time-correlated single photon counting measurement. For the first time, we found that g-CNN displays a layer-dependent indirect bandgap and layer-dependent charge carrier kinetics.展开更多
The carbon layers on implanted steel surface have been studied by means of Auger spectra. It is shown that the thickness of the carbon layer is proportional to the dose of implanted ions. By comparison with the result...The carbon layers on implanted steel surface have been studied by means of Auger spectra. It is shown that the thickness of the carbon layer is proportional to the dose of implanted ions. By comparison with the results of friction and wear tests, the friction coefficient is smaller than 0.20 at the first part of the friction coefficient curve. It is considered that the graphitic carbon layer on the top of steel is helpful to reducing the surface friction coefficient of steel.展开更多
基金supported by the National Key R&D Program of China(2021YFE0115800)the National Natural Science Foundation of China(22275142,22293022,U22B6011,52103285)+1 种基金the 111 National Project(Grant No.B20002)the Fundamental Research Funds for the Central Universities(2020-YB-005)。
文摘Silicon(Si)has gained popularity as a potential anodic material for Li-ion batteries(LIBs)due to its large theoretical capacity.However,low conductivity,large volume expansion,and side reactions during alloying and de-alloying lead to poor cyclic and bad high-rate performance,which has severely hindered its practical large-scale application.Herein,a novel stamen-structured Si-based anode material with a protective SiO_(x)layer and dual carbon layers(Si@SiO_(x)/C@C)is designed for high-performance LIBs.The protective SiO_(x)layer reduces side reactions and dual carbon layers enhance charge transport to improve reaction kinetics,while the unique structure provides buffering space for volume expansion.Such Si@SiO_(x)/C@C anode demonstrates impressive Li storage properties for a half-battery,including a discharge capacity of 2935 mA h g^(-1)at a current density 0.1 A g^(-1),cyclic performance(814 mA h g^(-1)at 2 A g^(-1)over 500 cycles and 988 mA h g^(-1)over 200 cycles at 1 A g^(-1))and a rate performance(609 mA h g^(-1)at 5 A g^(-1)).It also maintains a high reversible capacity of 131 mA h g^(-1)at 0.25 C after100 cycles for a full battery.This work provides insights into the novel design of multiple protective layers on Si-based anode materials for fast-charging and highly stable LIBs.
基金the National Natural Science Foundation of China(No.21703191)Key Project of Strategic New Industry of Hunan Province(No.2016GK4005 and No.2016GK4030)Research Innovation Project for Graduate students of Hunan Province(No.CX2017B302)。
文摘Among the many strategies to fabricate the silicon/carbon composite,yolk/double-shells structure can be regarded as an effective strategy to overcome the intrinsic defects of Si-based anode materials for Li-ion batteries(LIBs).Hereon,a facile and inexpensive technology to prepare silicon/carbon composite with yolk/double-shells structure is proposed,in which the double buffering carbon shells are fabricated.The silicon/carbon nanoparticles with core-shell structure are encapsulated by SiO_(2)and external carbon layer,and it shows the yolk/double-shells structure via etching the SiO_(2)sacrificial layer.The multiply shells structure not only significantly improves the electrical conductivity of composite,but also effectively prevents the exposure of Si particles from the electrolyte composition.Meanwhile,the yolk/double-shells structure can provide enough space to accommodate the volume change of the electrode during charge/discharge process and avoid the pulverization of Si particles.Moreover,the as-prepared YDS-Si/C shows excellent performance as anode of LIBs,the reversible capacity is as high as 1066 mA h g^(-1) at the current density of 0.5 A g^(-1) after 200 cycles.At the same time,the YDS-Si/C has high capacity retention and good cyclic stability.Therefore,the unique architecture design of yolk/double-shells for Si/C composite provides an instructive exploration for the development of next generation anode materials of LIBs with high electrochemical performances and structural stability.
基金financially supported by the National Key Technology R&D Program of China (No. 2017YFB0310704)the National Natural Science Foundation of China (Nos. 21773112, 21173119 and 21303083)+2 种基金Natural Science Foundation of the Higher Education Institutions of Jiangsu Province (No. 17KJB150001)the Natural Science Foundation of Jiangsu Province (No. BK20130563)the Fundamental Research Funds for the Central Universities
文摘In this work, a series of Pt nanocrystallines（Pt NCs） supported on TiO2 substrate with controlled thickness of carbon layers（C-Pt/TiO2） were synthesized. Well-dispersed Pt NCs were facilely synthesized at room temperature by a photo-reduction process in lytropic liquid crystal（LCs）. Surface tuning of the carbon layers on Pt/TiO2 catalysts was achieved by varying the calcination atmospheres（in argon, air, and oxygen） and characterized by XPS and HRTEM. The influence of the coated carbon layers on the catalytic activity of catalysts is investigated by CO oxidation reaction which presented the following ranks： C-Pt/TiO2-O2〉 C-Pt/TiO2-Air 〉 C-Pt/TiO2-Ar. It is found that the carbon layer coating can stabilize the Pt NCs and enable them anti-sintering at high temperature. This finding provides new insight into understanding the C-Pt/TiO2 ternary system for tuning their catalytic performance.
基金support from the Key-Area Research and Development Program of Guangdong Province(2019B111107002)the National Natural Science Foundation of China(52478266 and 52108231)+1 种基金the Basic and Applied Basic Research Fund of Guangdong Province(2023A1515012150 and 2023A1515012409)the Shenzhen Science and Technology Innovation Program(20220810140230001 and 20220810160453001).
文摘Polyacrylonitrile-based commercial carbon fibers(CFs)have garnered significant attention in mechanical applications because of their exceptional mechanical properties.However,their functional versatility relies heavily on the structural intricacies of duplex carbon layers.Current modification approaches,though effective,are encumbered by complexity and cost,limiting widespread adoption across diverse fields.We herein present a straightforward modification strategy centered on regulating carbon layers to unlock the multifunctional potential of CFs.Our method leverages two common anions,Cl^(-)and SO_(4)^(2-),to facilitate oxidation reactions in CFs under robust alkali and high voltage conditions.Cl^(-)effectively activates carbon layers,while SO_(4)^(2-)facilitates layer movement.The electrocatalytic activities of the resultant CFs are enhanced,with state-of-the-art performance as supercapacitors and exceptional stability.Moreover,our approach achieves a groundbreaking milestone by bending and fusing CFs without using binders.This breakthrough can reduce the manufacturing costs of CF-based products.It also facilitates the development of novel microelectronic devices.
基金partially supported by the National Natural Science Foundation of China(22479022)Liaoning Revitalization Talents Program(XLYC2007129)。
文摘Aqueous zinc metal batteries(ZMBs)which are environmentally benign and cheap can be used for grid-scale energy storage,but have a short cycling life mainly due to the poor reversibility of zinc metal anodes in mild aqueous electrolytes.A zincophilic carbon(ZC)layer was deposited on a Zn metal foil at 450°C by the up-stream pyrolysis of a hydrogen-bonded supramolecular substance framework,as-sembled from melamine(ME)and cyanuric acid(CA).The zincophilic groups(C=O and C=N)in the ZC layer guide uniform zinc plating/stripping and eliminate dendrites and side reactions.so that assembled symmetrical batteries(ZC@Zn//ZC@Zn)have a long-term service life of 2500 h at 1 mA cm^(−2) and 1 mAh cm^(−2),which is much longer than that of bare Zn anodes(180 h).In addition,ZC@Zn//V2O5 full batteries have a higher capacity of 174 mAh g^(−1) after 1200 cycles at 2 A g^(−1) than a Zn//V_(2)O_(5) counterpart(100 mAh g^(−1)).The strategy developed for the low-temperat-ure deposition of the ZC layer is a new way to construct advanced zinc metal anodes for ZMBs.
基金financially supported by the National Natural Science Foundation of China(Nos.61904090 and 62464010)Project(No.202306)of State Key Laboratory of Physical Chemistry of Solid Surfaces(Xiamen University)。
文摘Zinc-ion battery(ZIB)has been regarded as one of the most promising sustainable energy storage systems due to its low cost,safety,and attractive electrochemical performance.However,the metallic zinc anode with uneven deposition during cycling would result in significant capacity decay,low Coulombic efficiency,and electrolyte consumption,thus the undesirable cyclability severely hampers the practical applications.Herein,a phosphorus-doped carbon protective layer was coated onto the surface of Zn anode via using the plasma-enhanced chemical vapor deposition(PECVD)approach.Enhanced conductivity and lower nucleation overpotential induced by the P-doped carbon protective layer can effectively facilitate the ion diffusion kinetics and suppress side reactions.The as-fabricated P-C/Zn anode demonstrated excellent cycling stability during the zinc plating/stripping process,maintaining a low voltage hysteresis(34.8 m V)for over 1000 h under a current density of 2 m A/cm^(2)and a capacity of 2 m Ah/cm^(2).Moreover,the P-C/Zn||MnO_(2)full cell exhibited high specific capacity of about 252.5 m Ah/g at 2 A/g upon 700 long cycles.This study is helpful to design more efficient zinc-ion batteries towards the future applications.
基金the financial support from the project funded by the Education Department of Shaanxi Provincial Government(No.23JP116)the Natural Science Fund of Shaanxi Province(No.2024JC-YBMS-396)+1 种基金the National Natural Science Foundation of China(Nos.52171191 and 52371198)the Constructing National Independent Innovation Demonstration Zones(XM2024XTGXQ05).
文摘The proliferation of advanced electronics and devices has led to significant electromagnetic interference and pollution,resulting in heightened interest in electromagnetic interference(EMI)shielding materials in recent years.Carbon foam,as a typical porous carbonaceous material,demonstrates significant potential as an innovative EMI shielding material owing to its lightweight nature,exceptional porosity,flexibility,favorable processability,and environmental sustainability.Nonetheless,the configuration of carbon atoms within the carbon foam is significantly disordered,leading to its intrinsic conductivity being comparatively low.Consequently,its shielding efficacy cannot meet the standards required for commercial EMI materials.Herein,we propose a hierarchical engineering strategy to construct a carbon foam composite with high shielding efficacy.Specifically,the FeCo nanoparticles and carbon layer are concurrently integrated into the carbon foam matrix to modulate its magnetic characteristics and conductivity.The results demonstrate that the carbon-coated FeCo/carbon foam composite achieves a shielding effectiveness(SE)of 24 dB in the X-band,signifying a 240% improvement compared to the pristine carbon foam.Simultaneously,the composite also exhibits superior multifunctionalities involving flexibility,Joule heating,and hydrophobicity.This study provides a facile and effective routine to regulate the shielding efficacy of EMI shielding materials.
基金the support from NSRL for the XAS experiments.This work was financially supported by the National Key R&D Program of China(No.2020YFA0406103)the National Natural Science Foundation of China(No.U1932211)+1 种基金the Collaborative Innovation Center of Suzhou Nano Science&Technology,the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)the 111 Project.
文摘In-situ observation of the charge transfer plays a key role in understanding the working mechanism of hematite for solar water oxidation.Here by using in-situ X-ray absorption spectroscopy(XAS),the electron injection from illuminated hematite(photon-excited electron)to the surface carbon layer can be clearly identified,which can facilitate the charge separation and then improve the performance.As a result,the carbon-coated and Sn-doped hematite photoanode(C-Sn-Fe_(2)O_(3))shows a greatly enhanced photocurrent density of 2.3 mA/cm^(2) at 1.23 VRHE,which is 2.3 times that of the pristine hematite.The injected electron can modify the chemical state of surface groups in the carbon layer and be quickly transferred to the electrode due to the high conductivity of the carbon layer,leaving behind the high-valence Fe^(4+)with high oxidation capability to enhance the performance.By coupling with the FeNiOOH co-catalyst,the photoanode can finally achieve a high photocurrent density of 3.0 mA/cm^(2) at 1.23 VRHE with a low onset potential of 0.76 VRHE.The understanding of the charge migration route by using in-situ XAS offers a novel way for the design of highly efficient solar water oxidation materials.
基金support from the National Natural Science Foundation of China(61574091)National Natural Science Foundation of China Key Program(50730008).
文摘Although room-temperature superconductivity is still difficult to achieve,researching materials with electrical conductivity significantly higher than that of copper will be of great importance in improving energy efficiency,reducing costs,lightening equipment weight,and enhancing overall performance.Herein,this study presents a novel copper-carbon nanofilm composite with enhanced conductivity which has great applications in the electronic devices and electrical equipment.Multilayer copper-carbon nanofilms and interfaces with superior electronic structures are formed based on copper materials using plasma immersion nanocarbon layer deposition technology,effectively enhancing conductivity.Experimental results show that for a five-layer copper-carbon nanofilm composite,the conductivity improves significantly when the thickness of the carbon nanofilm increases.When the carbon nanofilm accounts for 16%of the total thickness,the overall conductivity increases up to 30.20%compared to pure copper.The mechanism of the enhanced conductivity is analyzed including roles of copper atom adsorption sites and electron migration pathways by applying effective medium theory,first-principles calculations and density of states analysis.Under an applied electric field,the high-density electrons in the copper film can migrate into the nanocarbon film,forming highly efficient electron transport channels,which significantly enhance the material’s conductivity.Finally,large-area electrode coating equipment is developed based on this study,providing the novel and robust strategy to enhance the conductivity of copper materials,which enables industrial application of copper-carbon nanocomposite films in the field of high conductivity materials.
基金funded by the Norwegian University of Life Sciences(NMBU)a strategic institutional research program at the Norwegian Institute of Bioeconomy Research(NIBIO).
文摘A key property of the boreal forest is that it stores huge amounts of carbon(C),especially belowground in the soil.Amounts of C stored in the uppermost organic layer of boreal forest soils vary greatly in space due to an interplay between several variables facilitating or preventing C accumulation.In this study,we split C stocks into the organic layer and charcoal C due to their difference in origin,stability,and ecological properties.We compared organic layer C and charcoal C stocks in two regions of south-central Norway(Trillemarka and Varaldskogen),characterized by Scots pine and Norway spruce forests with varying fire histories.We used structural equation modeling to investigate how vegetation composition,hydrotopography,and soil properties interplay to shape organic layer C and charcoal C stocks.Pine forests consistently contained larger organic layer C stocks than spruce forests.Charcoal stocks,in contrast,were less consistent across both forest types and study regions as pine forests had higher charcoal C stocks than spruce forests in Trillemarka,while the two forest types contained equal charcoal C stocks in Varaldskogen.Charcoal and soil organic layer C stocks increased with higher fire frequencies(number of fire events over the last 600 years),but not with a shorter time since last fire(TSF).Additionally,vegetation composition,terrain slope,and soil moisture were the most important drivers of the organic layer C stocks,while charcoal C stocks were mainly controlled by the depth of the organic layer.Also,microtopography was of importance for organic layer C and charcoal C,since depressions in the forest floor had more charcoal C than well-drained minor hills.
基金supported by the National Natural Science Foundation of China(No.21972171)the Fundamental Research Funds for the Central Universities,South-Central MinZu University(Nos.CZQ23037,CZY23018)+1 种基金the Hubei Provincial Natural Science Foundation,China(No.2021CFA022)the Innovation and Entrepreneurship Training Program Funded by South-Central Minzu University(No.S202310524033).
文摘Photogenerated charge separation is a challenging step in semiconductor-based photosynthesis.Though numerous efforts have been devoted to developing multi-component photocatalyst heterostructures for improving charge separation efficiency,the short distance between electrons and holes-aggregated regions still leads to undesirable charge recombination.Herein,a facile and commercial in-situ synthesis method was designed to directly prepare a three-component Au–carbon–TiO_(2)photocatalyst from Ti_(3)C_(2)MXene,air,CO_(2),and HAuCl_(4),in which the carbon layer bridged Au and TiO_(2)nanoparticles for stable and efficient photocatalytic hydrogen production.Kelvin probe measurements and density functional theory(DFT)calculations demonstrated that a multi-interfacial charge transmission network was successfully constructed to achieve a directional and long-distance spatial charge separation/transfer channel between TiO_(2)and Au through carbon layer,desirably inhibiting the recombination of photogenerated charge carriers.The hydrogen production rate of the formed three-component Au/C–TiO_(2)(CTA)photocatalyst was demonstrated to be 27 times higher than that of Au–TiO_(2),which also surpassed many reported Ti_(3)C_(2)MXene-derived carbon–TiO_(2)photocatalysts.This work sheds light on the ingenious use of 2D MXene to form a well-behaved TiO_(2)-based photocatalytic system and helps to propose future design principles in accelerating charge transfer.
文摘Converting sunlight directly to fuels and chemicals is a great latent capacity for storing renewable energy.Due to the advantages of large surface area,short diffusion paths for electrons,and more exposed active sites,few‐layer carbon nitride(FLCN)materials present great potential for production of solar fuels and chemicals and set off a new wave of research in the last few years.Herein,the recent progress in synthesis and regulation of FLCN‐based photocatalysts,and their applications in the conversion of sunlight into fuels and chemicals,is summarized.More importantly,the regulation strategies from chemical modification to microstructure control toward the production of solar fuels and chemicals has been deeply analyzed,aiming to inspire critical thinking about the effective approaches for photocatalyst modification rather than developing new materials.At the end,the key scientific challenges and some future trend of FLCN‐based materials as advanced photocatalysts are also discussed.
基金supported by the National Key R&D Program of China(No.2016YFC1102802)the Natural Science Foundation of Jilin Province(No.20200201020JC)the Open Project of State Key Laboratory of Supramolecular Structure and Materials(No.sklssm202011)。
文摘Due to the increasingly depleted limited fossil fuel resources,the development of renewable energy is the key to promote sustainable development which is an important part of the energy strategy[1].NH3 is one of most important and largest chemical productions in the world,it can be used as a feedstock for nitrogen fertilizer productions[2,3]or as a carbon-free energy carrier[4,5].
基金financially supported by the National Natural Science Foundation of China (Nos.22005167 and 21905152)Shandong Provincial Natural Science Foundation of China (Nos.ZR2020QB125, ZR2020MB045 and ZR2022QE003)+2 种基金China Postdoctoral Science Foundation (Nos.2021M693256, 2021T140687 and 2022M713249)Qingdao Postdoctoral Applied Research Project, Taishan Scholar Project of Shandong Province of China (No.tsqn202211160)the Youth Innovation Team Project for Talent Introduction and Cultivation in Universities of Shandong Province。
文摘Lithium-ion capacitors(LICs) of achieving high power and energy density have garnered significant attention. However, the kinetics unbalance between anode and cathode can impede the application of LICs. Vanadium nitride(VN) with a high theoretical specific capacity(~ 1200 m Ah·g^(-1)) is a better pseudocapacitive anode to match the response of cathode in LICs. However, the insertion/extraction of Li-ions in VN's operation results in significant volume expansion. Herein, the VN/N-r GO-5composite that three-dimentional(3D) dicyandiamidederived-carbon(DDC) tightly wrapped VN quantum dots(VN QDTs) on two-dimentional(2D) reduced graphene oxid(r GO) was prepared by a facile strategy. The VN QDTs can reduce ion diffusion length and improve charge transfer kinetics. The 2D r GO as a template provides support for nanoparticle dispersion and improves electrical conductivity. The 3D DDC tightly encapsulated with VN QDTs mitigates agglomeration of VN particles as well as volume expansion. Correspondingly, the LICs with VN/Nr GO-5 composite as anode and activated carbon(AC) as cathode were fabricated, which exhibits a high energy density and power density. Such strategy provides a perspective for improving the electrochemical properties of LIC anode materials by suppressing volume expansion and enhancing conductivity.
基金supported by the Royal Academy of Engineering,United Kingdom
文摘An extensive study has been conducted on the proton exchange membrane fuel cells （PEMFCs） with reducing Pt loading. This is commonly achieved by developing methods to increase the utilization of the platinum in the catalyst layer of the electrodes. In this paper, a novel process of the catalyst layers was introduced and investigated. A mixture of carbon powder and Nafion solution was sprayed on the glassy carbon electrode （GCE） to form a thin carbon layer. Then Pt particles were deposited on the surface by reducing hexachloroplatinic （IV） acid hexahydrate with methanoic acid. SEM images showed a continuous Pt gradient profile among the thickness direction of the catalytic layer by the novel method. The Pt nanowires grown are in the size of 3 nm （diameter） x l0 nm （length） by high solution TEM image. The novel catalyst layer was characterized by cyclic voltammetry （CV） and scanning electron microscope （SEM） as compared with commercial Pt/C black and Pt catalyst layer obtained from sputtering. The results showed that the platinum nanoparticles deposited on the carbon powder were highly utilized as they directly faced the gas diffusion layer and offered easy access to reactants （oxygen or hydrogen）.
基金financially supported by the National Natural Science Foundation of China(No.21376276)the Specialfunded Program on National Key Scientific Instruments and Equipment Development of China(No.2012YQ230043)+1 种基金Guangdong Province Sci&Tech Bureau(Key Strategic Project No.2008A080800024)the Fundamental Research Funds for the Central Universities
文摘Relatively well crystallized and high aspect ratio Mg-Al layered double hydroxides（LDHs） were prepared by coprecipitation process in aqueous solution and further rehydrated to an organic modified LDH（OLDH） in the presence of surfactant. The intercalated structure and high aspect ratio of OLDH were verified by X-ray diffraction（XRD） and scanning electron microscopy（SEM）. A series of poly（propylene carbonate）（PPC）/OLDH composite films with different contents of OLDH were prepared via a melt-blending method. Their cross section morphologies, gas barrier properties and tensile strength were investigated as a function of OLDH contents. SEM results show that OLDH platelets are well dispersed within the composites and oriented parallel to the composite sheet plane. The gas barrier properties and tensile strength are obviously enhanced upon the incorporation of OLDH. Particularly, PPC/2%OLDH film exhibits the best barrier properties among all the composite films. Compared with pure PPC, the oxygen permeability coefficient（OP） and water vapor permeability coefficient（WVP） is reduced by 54% and 17% respectively with 2% OLDH addition. Furthermore, the tensile strength of PPC/2%OLDH is 83% higher than that of pure PPC with only small lose of elongation at break. Therefore, PPC/OLDH composite films show great potential application in packaging materials due to its biodegradable properties, superior oxygen and moisture barrier characteristics.
基金Funded by the National Natural Science Foundation of China(No.50878169)the Project of State Key Laboratory of Refractories and Metallurgy(Wuhan University of Science and Technology)(No.G201407)
文摘Composite made of short-cut carbon fiber mat and vinyl ester resin was observed to be an effective sensor for tensile strain up to 6 000με. Based on its strain sensitivity, a skin-like sensitive layer which can continuously cover the structural surface to sense strain in large area was developed. The sensitive layer was applied to continuously monitor the deformation of a simply supported beam. The result indicates that the fractional change in electrical resistance of the sensitive layer reversibly reflects the beam deformation in each section and describes the distribution of the average strain of the beam. The effect of temperature change on the monitoring was studied by monitoring tests conducted at different temperatures ranging from 20 to 80 ℃, which reveals temperature sensitivity in the sensitive layer and the temperature dependence of the piezoresistive behavior when the temperature exceeds 50 ℃. By the application of differential conaection principle, a method for temperature compensation was established and the gauge factor for the monitoring was dramatically increased. This method was verified experimentally.
基金supported by the National High-Tech Research and Development Program of China (No.2009AA03Z116)the National Natural Science Foundation of China (No.50971020)
文摘To extend the application of carbon nanotubes （CNTs） and explore novel aluminum matrix composites,CNTs were coated by molybdenum layers using metal organic chemical vapor deposition,and then Mo-coated CNT （Mo-CNT）/Al composites were prepared by the combination processes of powder mixing and spark plasma sintering.The influences of powder mixing and Mo-CNT content on the mechanical properties and electrical conductivity of the composites were investigated.The results show that magnetic stirring is better than mechanical milling for mixing the Mo-CNTs and Al powders.The electrical conductivity of the composites decreases with increasing Mo-CNT content.When the Mo-CNT content is 0.5wt%,the tensile strength and hardness of Mo-CNT/Al reach their maximum values.The tensile strength of 0.5wt% Mo-CNT/Al increases by 29.9%,while the electrical conductivity only decreases by 7.1%,relative to sintered pure Al.The phase analysis of Mo-CNT/Al composites reveals that there is no formation of Al carbide in the composites.
基金Financial supports by the National Natural Science Foundation of China (No. 21373269)the Fundamental Research Funds for the Central Universities and the Research Funds of Renmin University of China(No. 10XNJ047)
文摘We investigated the thickness effect on the photophysics and charge carrier kinetics of graphitic carbon nitride nanoflakes （g-CNN） by using ultraviolet visible diffuse reflectance spectroscopy, atomic force microscopy, femtosecond transient absorption spectroscopy, and picosecond time-correlated single photon counting measurement. For the first time, we found that g-CNN displays a layer-dependent indirect bandgap and layer-dependent charge carrier kinetics.
文摘The carbon layers on implanted steel surface have been studied by means of Auger spectra. It is shown that the thickness of the carbon layer is proportional to the dose of implanted ions. By comparison with the results of friction and wear tests, the friction coefficient is smaller than 0.20 at the first part of the friction coefficient curve. It is considered that the graphitic carbon layer on the top of steel is helpful to reducing the surface friction coefficient of steel.
