Developing biomass platform compounds into high value-added chemicals is a key step in renewable resource utilization.Herein,we report porous carbon-supported Ni-ZnO nanoparticles catalyst(Ni-ZnO/AC)synthesized via lo...Developing biomass platform compounds into high value-added chemicals is a key step in renewable resource utilization.Herein,we report porous carbon-supported Ni-ZnO nanoparticles catalyst(Ni-ZnO/AC)synthesized via low-temperature coprecipitation,exhibiting excellent performance for the selective hydrogenation of 5-hydroxymethylfurfural(HMF).A linear correlation is first observed between solvent polarity(E_(T)(30))and product selectivity within both polar aprotic and protic solvent classes,suggesting that solvent properties play a vital role in directing reaction pathways.Among these,1,4-dioxane(aprotic)favors the formation of 2,5-bis(hydroxymethyl)furan(BHMF)with 97.5%selectivity,while isopropanol(iPrOH,protic)promotes 2,5-dimethylfuran production with up to 99.5%selectivity.Mechanistic investigations further reveal that beyond polarity,proton-donating ability is critical in facilitating hydrodeoxygenation.iPrOH enables a hydrogen shuttle mechanism where protons assist in hydroxyl group removal,lowering the activation barrier.In contrast,1,4-dioxane,lacking hydrogen bond donors,stabilizes BHMF and hinders further conversion.Density functional theory calculations confirm a lower activation energy in iPrOH(0.60 eV)compared to 1,4-dioxane(1.07 eV).This work offers mechanistic insights and a practical strategy for solvent-mediated control of product selectivity in biomass hydrogenation,highlighting the decisive role of solvent-catalyst-substrate interactions.展开更多
Developing effective strategies to regulate graphene’s conduction loss and polarization has become a key to expanding its application in the electromagnetic wave absorption(EMWA)field.Based on the unique energy band ...Developing effective strategies to regulate graphene’s conduction loss and polarization has become a key to expanding its application in the electromagnetic wave absorption(EMWA)field.Based on the unique energy band structure of graphene,regulating its bandgap and electrical properties by introducing heteroatoms is considered a feasible solution.Herein,metal-nitrogen doping reduced graphene oxide(M–N-RGO)was prepared by embedding a series of single metal atoms M–N_(4) sites(M=Mn,Fe,Co,Ni,Cu,Zn,Nb,Cd,and Sn)in RGO using an N-coordination atom-assisted strategy.These composites had adjustable conductivity and polarization to optimize dielectric loss and impedance matching for efficient EMWA performance.The results showed that the minimum reflection loss(RL_(min))of Fe–N-RGO reaches−74.05 dB(2.0 mm)and the maximum effective absorption bandwidth(EAB_(max))is 7.05 GHz(1.89 mm)even with a low filler loading of only 1 wt%.Combined with X-ray absorption spectra(XAFS),atomic force microscopy,and density functional theory calculation analysis,the Fe–N_(4) can be used as the polarization center to increase dipole polarization,interface polarization and defect-induced polarization due to d-p orbital hybridization and structural distortion.Moreover,electron migration within the Fe further leads to conduction loss,thereby synergistically promoting energy attenuation.This study demonstrates the effectiveness of metal-nitrogen doping in regulating the graphene′s dielectric properties,which provides an important basis for further investigation of the loss mechanism.展开更多
Metal-organic frameworks(MOFs)have been considered as great contender and promising electrode materials for supercapacitors.However,their low capacity,aggregation,and poor porosity have necessitated the exploration of...Metal-organic frameworks(MOFs)have been considered as great contender and promising electrode materials for supercapacitors.However,their low capacity,aggregation,and poor porosity have necessitated the exploration of new approaches to enhance the performance of these active materials.In this study,sphere-like MOF were in-situ grown and it subsequently burst,transformed into a desired metal oxide heterostructure comprising n-type ZnO and p-type NiO(ZnO/NiO-350).The resulting optimized flower-like structure,composed of interlaced nanoflakes derived from MOFs,greatly improved the active sites,porosity,and functionality of the electrode materials.The ZnO/NiO-350 electrode exhibited superior electrochemical activities for supercapacitors,compared to the parent MOF,bare n-type,and p-type counterparts.The specific capacitance can reach to 543 F g^(-1) at a current density of 1 A g^(-1).Theoretical modeling and simulations were employed to gain insights into the atomic-scale properties of the materials.Furthermore,an assembled hybrid device using active carbon and ZnO/NiO-350 as electrodes demonstrated excellent energy density of 44 Wh kg^(-1) at a power density of 1.6 Kw kg^(-1).After 5000 cycles at 10 A g^(-1),the cycling stability remained excellent 80%of the initial capacitance.Overall,such evaluation of unique electrode with superior properties may be useful for the next generation supercapacitor electrode.展开更多
The evolution of energy storage technology has seen remarkable progress,with a shift from pure metals to sophisticated,tailor-made active materials.The synthesis of nanostructures with exceptional properties is crucia...The evolution of energy storage technology has seen remarkable progress,with a shift from pure metals to sophisticated,tailor-made active materials.The synthesis of nanostructures with exceptional properties is crucial in the advancement of electrode materials.In this regard,our study highlights the fabrication of a novel,oriented heterostructure comprised of Zn-Mn-Co-telluride grown on a pre-oxidized copper mesh using a hydrothermal method followed by a solvothermal process.This innovative approach leads to the formation of the Zn-Mn-Cotelluride@CuO@Cu heterostructure,which demonstrates the unique oriented morphology.It outperforms both Zn-Mn-Co-telluride@Cu and CuO@Cu by exhibiting lower electrical resistivity,increased redox activity,higher specific capacity,and improved ion diffusion characteristics.The conductivity enhancements of the heterostructure are corroborated by density functional theory(DFT)calculations.When utilized in a hybrid supercapacitor(HSC)alongside activated carbon(AC)electrodes,the Zn-Mn-Co-telluride@CuO@Cu heterostructurebased HSC achieves an energy density of 75.7 Wh kg^(-1).Such findings underscore the potential of these novel electrode materials to significantly impact the design of next-generation supercapacitor devices.展开更多
Objectives Professional identity plays an important role in the long-term development of nurses,and it will change when public health emergency occurs.The objective of this study is to investigate the factors associat...Objectives Professional identity plays an important role in the long-term development of nurses,and it will change when public health emergency occurs.The objective of this study is to investigate the factors associated with the professional identity of nursing undergraduates in the epidemic of COVID-19.Methods A cross-sectional survey design with convenience sampling was used.A total of 3,875 nursing undergraduates were recruited from seven universities across China from March to April 2020.A general information questionnaire was used to collect students’information,and the Professional Identity Questionnaire for Nurse Students was used to survey their professional identity during the early and later stages of the first wave of the COVID-19 epidemic.Results The score of professional identity in the later stage(59.49±12.41)was higher than that in the early stage(56.96±12.61).The stepwise regression indicated that several factors were associated with professional identity,including gender,residential area,major,impact of the epidemic on intention to work after graduation,reasons for choosing nursing major and students’scores of professional identity in early stage.Conclusions Nursing educators can utilize the positive impact of responding to public health emergencies to increase the professional identity of students.Meanwhile,educators should give those students with lower professional identity more targeted education to cultivate their professional identity after the occurrence of public health emergencies.展开更多
Polarization and conductance losses are the fundamental dielectric attenuation mechanisms for graphene-based absorbers, but it is not fully understood in revealing the loss mechanism of affect graphene itself. For the...Polarization and conductance losses are the fundamental dielectric attenuation mechanisms for graphene-based absorbers, but it is not fully understood in revealing the loss mechanism of affect graphene itself. For the first time, the reduced graphene oxide(RGO) based absorbers are developed with regulatory absorption properties and the absorption mechanism of RGO is mainly originated from the carrier injection behavior of trace metal Fe nanosheets on graphene. Accordingly, the minimum reflection loss(RLmin) of Fe/RGO-2composite reaches-53.38 dB(2.45 mm), and the effective absorption bandwidth achieves 7.52 GHz(2.62 mm) with lower filling loading of 2 wt%. Using off-axis electron hologram testing combined with simulation calculation and carrier transport property experiments, we demonstrate here the carrier injection behavior from Fe to graphene at the interface and the induced charge accumulation and rearrangement, resulting in the increased interfacial and dipole polarization and the conductance loss. This work has confirmed that regulating the dielectric property of graphene itself by adding trace metals can not only ensure good impedance matching, but also fully exploit the dielectric loss ability of graphene at low filler content,which opens up an efficient way for designing lightweight absorbers and may be extended to other types materials.展开更多
For efficient electrolysis of water for hydrogen generation or other valueadded chemicals, it is highly relevant to develop low-temperature synthesis of low-cost and high-e ciency metal sulfide electrocatalysts on a l...For efficient electrolysis of water for hydrogen generation or other valueadded chemicals, it is highly relevant to develop low-temperature synthesis of low-cost and high-e ciency metal sulfide electrocatalysts on a large scale. Herein, we construct a new core–branch array and binder-free electrode by growing Ni_3S_2 nanoflake branches on an atomic-layer-deposited(ALD) TiO_2 skeleton. Through induced growth on the ALD-TiO_2 backbone, cross-linked Ni_3S_2 nanoflake branches with exposed { 210} highindex facets are uniformly anchored to the preformed TiO_2 core forming an integrated electrocatalyst. Such a core–branch array structure possesses large active surface area, uniform porous structure, and rich active sites of the exposed { 210 } high-index facet in the Ni_3S_2 nanoflake. Accordingly, the TiO_2@Ni_3S_2 core/branch arrays exhibit remarkable electrocatalytic activities in an alkaline medium, with lower overpotentials for both oxygen evolution reaction(220 mV at 10 mA cm^(-2)) and hydrogen evolution reaction(112 m V at 10 mA cm^(-2)), which are better than those of other Ni_3S_2 counterparts. Stable overall water splitting based on this bifunctional electrolyzer is also demonstrated.展开更多
Rational design of cost-effective high-performance electrocatalysts for oxygen evolution reaction (OER) is of great significance for electrochemical water splitting. Herein, we adopt a nitrogen doping method to fabric...Rational design of cost-effective high-performance electrocatalysts for oxygen evolution reaction (OER) is of great significance for electrochemical water splitting. Herein, we adopt a nitrogen doping method to fabricate self-supported N-doped CoO nanowire arrays (N-CoO) as active electrocatalysts via a facile hydrothermal combined doping method. The N-CoO nanowires are strongly composited with the carbon cloth substrate forming free-standing electrode with reinforced stability and high electronic conductivity. Owing to the increased accessible and electroactive areas, rich/short pathways for charge transfer and enhanced electronic conductivity, the N-CoO electrode exhibits excellent electrocatalytic performance for OER with a low overpotential (319 mV at 10 mA cm^-2 and 410 mV at 100 mA cm^-2) and a low Tafel slope of 74 mV dec^-1 as well as superior long-term stability with no decay in 24 h continuous test in alkaline solution. Our reported design and optimization strategy provide a promising way to construct interesting well-aligned arrays for application in energy storage and conversion.展开更多
It is important but challenging to design and fabricate an efficient and cost-effective electrocatalyst for the oxygen evolution reaction(OER). Herein, we report free-standing 3 D nickel arrays with a cross-linked por...It is important but challenging to design and fabricate an efficient and cost-effective electrocatalyst for the oxygen evolution reaction(OER). Herein, we report free-standing 3 D nickel arrays with a cross-linked porous structure as interesting and high-performance electrocatalysts for OER via a facile one-step electrodeposition method. The 3 D nickel arrays are strongly anchored on the substrate, forming self-supported electrocatalysts with reinforced structural stability and high electrical conductivity. Because of their increased active surface area, abundant channels for electron/ion transportation and enhanced electronic conductivity, the designed 3 D nickel arrays exhibit superior electrocatalytic OER performance with a low overpotential(496 mV at 50 mA cm–2) and a small Tafel slope(43 mV dec–1) as well as long-term stability(no decay after 24 h) in alkaline solution. Our proposed rational design strategy may open up a new way to construct other advanced 3 D porous materials for widespread application in electrocatalysis.展开更多
Controllable synthesis of highly active micro/nanostructured metal electrocatalysts for oxygen evolution reaction(OER) is a particularly significant and challenging target.Herein,we report a 3D porous sponge-like Ni m...Controllable synthesis of highly active micro/nanostructured metal electrocatalysts for oxygen evolution reaction(OER) is a particularly significant and challenging target.Herein,we report a 3D porous sponge-like Ni material,prepared by a facile hydrothermal method and consisting of cross-linked micro/nanofibers,as an integrated binder-free OER electrocatalyst.To further enhance the electrocatalytic performance,an N-doping strategy is applied to obtain N-doped sponge Ni(N-SN) for the first time,via NH3 annealing.Due to the combination of the unique conductive sponge structure and N doping,the as-obtainedN-SN material shows improved conductivity and a higher number of active sites,resulting in enhanced OER performance and excellent stability.Remarkably,N-SN exhibits a low overpotential of 365 mV at 100 mA cm-2 and an extremely small Tafel slope of 33 mV dec-1,as well as superior long-term stability,outperforming unmodified sponge Ni.Importantly,the combination of X-ray photoelectron spectroscopy and near-edge X-ray adsorption fine structure analyses shows that γ-NiOOH is the surface-active phase for OER.Therefore,the combination of conductive sponge structure and N-doping modification opens a new avenue for fabricating new types of high-performance electrodes with application in electrochemical energy conversion devices.展开更多
Human civilization has been relentlessly inspired by the nurturing lessons;nature is teaching us.From birds to airplanes and bullet trains,nature gave us a lot of perspective in aiding the progress and development of ...Human civilization has been relentlessly inspired by the nurturing lessons;nature is teaching us.From birds to airplanes and bullet trains,nature gave us a lot of perspective in aiding the progress and development of countless industries,inventions,transportation,and many more.Not only that nature inspired us in such technological advances but also,nature stimulated the advancement of micro-and nanostructures.Nature-inspired nanoarchitectures have been consid-ered a favorable structure in electrode materials for a wide range of applications.It offers various positive attributes,especially in energy storage applications,such as the formation of hierarchical two-dimen-sional and three-dimensional interconnected networked structures that benefit the electrodes in terms of high surface area,high porosity and rich surface textural features,and eventually,delivering high capacity and outstanding overall material stability.In this review,we compre-hensively assessed and compiled the recent advances in various nature-inspired based on animal-and human-inspired nanostructures used for supercapacitors.This comprehensive review will help researchers to accommodate nature-inspired nanostructures in industrializing energy storage and many other applications.展开更多
Organic active units often transform into radical intermediates during the redox processes but exhibit poor cycling stability due to the uncontrollable redox of the radicals. Herein, we report a facile and efficient s...Organic active units often transform into radical intermediates during the redox processes but exhibit poor cycling stability due to the uncontrollable redox of the radicals. Herein, we report a facile and efficient strategy to modulate the molecular orbital energies, charge transport capacities, and spin electron densities of the active units in covalent organic frameworks(COFs) via regulating the conjugated unit size to optimize the redox activity and stability of the organic radicals. COFs based on different imide conjugated units exhibit tunable discharge voltages, rate performance and cycling stabilities. Detailed characterizations and theoretical calculation reveal that imide radicals are the important active intermediates during the redox processes of these COFs. Specifically, increasing the size of the imide conjugated units could effectively delocalize the radical electrons and improve the stability of the COFs electrodes. This study offers a very effective strategy to modulate the redox chemistry of organic materials for electrochemical energy storage.展开更多
Rational design of advanced cost-effective electrocatalysts is vital for the development of water electrolysis. Herein, we report a novel binder-free efficient CoS@CoOcore/shell electrocatalysts for oxygen evolution r...Rational design of advanced cost-effective electrocatalysts is vital for the development of water electrolysis. Herein, we report a novel binder-free efficient CoS@CoOcore/shell electrocatalysts for oxygen evolution reaction（OER） via a combined hydrothermal-sulfurization method. The sulfurized net-like CoSnanoflakes are strongly anchored on the CoOnanowire core forming self-supported binder-free core/shell electrocatalysts. Positive advantages including larger active surface area of CoSnanoflakes,and reinforced structural stability are achieved in the CoS@CoOcore/shell arrays. The OER performances of the CoS@CoOcore/shell arrays are thoroughly tested and enhanced electrocatalytic performance with lower over-potential(260 m V at 20 m A cm) and smaller Tafel slopes（56 mV dec-1） as well as long-term durability are demonstrated in alkaline medium. Our proposed core/shell smart design may provide a new way to construct other advanced binder-free electrocatalysts for applications in electrochemical catalysis.展开更多
In the original publication,Figure S4 is an ancillary image to compare the specific surface areas of TiO2/Ni3S2 and Ni3S2 samples and it was incorrectly published.To better serve our readers,the correct figure is prov...In the original publication,Figure S4 is an ancillary image to compare the specific surface areas of TiO2/Ni3S2 and Ni3S2 samples and it was incorrectly published.To better serve our readers,the correct figure is provided in this correction.The BET values are correct and unaffected.The corresponding figure caption,data analysis and conclusions are not affected and thus not to be changed.The authors would like to apologize for any inconvenience caused.展开更多
This study aimed to investigate the chemical constituents from the flowers of Dendrobium chrysanthum and determine its bioactive compounds. [Method] The compounds were extracted by 95% alcohol and isolated by column c...This study aimed to investigate the chemical constituents from the flowers of Dendrobium chrysanthum and determine its bioactive compounds. [Method] The compounds were extracted by 95% alcohol and isolated by column chromatography on silica gel and Sephadex LH-20. Their structures were identified by spectroscopic analysis （1H NMR, 13CNMR and ElMS）. [Result] Nine compounds were obtained and identified as stigmasterol , β-sitosterol , linoleic acid , stigmast-4-en-3-one , dibutyl phthalate , moscatilin , ergosterol , ergosterol peroxide and daucosterol . [Conclusion] Al compounds were isolated from its flowers for the first time.展开更多
MXenes(inorganic metal carbides,nitrides,and carbonitrides)are currently the rising star of two-dimensional(2D)family.After its discovery in 2011,initial research was concentrated on pristine MXenes only.However,in th...MXenes(inorganic metal carbides,nitrides,and carbonitrides)are currently the rising star of two-dimensional(2D)family.After its discovery in 2011,initial research was concentrated on pristine MXenes only.However,in the last few years,the MXene family has been expanded with the exploration of novel double MXenes,synthesis of non-Ti MXenes,and heteroatom doping of MXenes.The current review article delivers an exclusive overview of the current research trends on the heteroatom doping of MXenes.The recent advances in heteroatom doping of MXenes(majorly Ti-MXenes)for energy storage/conversion applications including secondary batteries(Li-ion,Li–S,Na–S,Na-ion,K-ion,Zn-ion batteries),supercapacitors,electrocatalysis,etc.are summarized.A brief overview of the defects as well as doping in various 2D materials is included in the manuscript.Various doping strategies of MXenes are outlined.Moreover,the impact of artificial intelligence/machine learning on MXene research is also concisely discussed.Additionally,the advantages of doping on MXenes are discussed in detail.Lastly,the existing challenges and future prospects of doped MXenes are addressed.It is expected that the current review will open new prospects for the fabrication of advanced energy devices through heteroatom doping of MXenes.展开更多
MXene has garnered widespread recognition in the scientific com-munity due to its remarkable properties,including excellent thermal stability,high conductivity,good hydrophilicity and dispersibility,easy processabilit...MXene has garnered widespread recognition in the scientific com-munity due to its remarkable properties,including excellent thermal stability,high conductivity,good hydrophilicity and dispersibility,easy processability,tunable surface properties,and admirable flexibility.MXenes have been categorized into different families based on the number of M and X layers in M_(n+1)X_(n),such as M_(2)X,M_(3)X_(2),M_(4)X_(3),and,recently,M_(5)X_(4).Among these families,M_(2)X and M_(3)X_(2),par-ticularly Ti_(3)C_(2),have been greatly explored while limited studies have been given to M_(5)X_(4)MXene synthesis.Meanwhile,studies on the M_(4)X_(3)MXene family have developed recently,hence,demanding a compilation of evaluated studies.Herein,this review provides a systematic overview of the latest advancements in M_(4)X_(3)MXenes,focusing on their properties and applications in energy storage devices.The objective of this review is to provide guidance to researchers on fostering M_(4)X_(3)MXene-based nanomaterials,not only for energy storage devices but also for broader applications.展开更多
Low cost processing of lignocellulosic biomass is of great importance for sustainable chemistry and engineering.Herein,a low cost system composed of 1-butyl-3-methylimidazolium chloride([C_(4)C_(1) im]Cl),HCl and form...Low cost processing of lignocellulosic biomass is of great importance for sustainable chemistry and engineering.Herein,a low cost system composed of 1-butyl-3-methylimidazolium chloride([C_(4)C_(1) im]Cl),HCl and formaldehyde(FA)was developed for the pretreatment of corn stalk at 80℃.The efficiency of this technology was compared with that in dioxane system or without FA addition.Due to FA stabilization,the extent of acid-hydrolysis of carbohydrate fraction can be significantly decreased while 70%above of lignin was removed with the pretreatment of[C_(4)C_(1) im]Cl/HCl/FA system at 80℃for 2 h.A maximum reducing sugar yield of 93.7%and glucose concentration of 7.0 mg·ml^(-1) were subsequently obtained from enzymatic hydrolysis of the slurry.There were great differences in compositions of small molecule degraded products obtained with FA addition or not.The present[C_(4)C_(1) im]C_(l) based system exhibits great potential of substituting volatile organic solvents(i.e.dioxane)in developing low cost lignocellulosic biomass pretreatment at low temperature.Also,this work would gain insight into understanding on the roles of stabilization methods on the economic improvement of IL based biomass processing.展开更多
African swine fever(ASF)is an acute and fatal hemorrhagic disease in domestic pigs and wild boars caused by African swine fever virus(ASFV)that currently threatens the pig industry worldwide.Since the 2018 ASF outbrea...African swine fever(ASF)is an acute and fatal hemorrhagic disease in domestic pigs and wild boars caused by African swine fever virus(ASFV)that currently threatens the pig industry worldwide.Since the 2018 ASF outbreak in China,ASFV has evolved and caused diverse clinical manifestations,such as chronic and asymptomatic infections.Therefore,it is important to understand the molecular mechanisms underlying ASFV attenuation in the feld.Here,we isolated three ASFVs from one diseased and two asymptomatic pigs by using primary porcine alveolar macrophages(PAMs)from both domestic pigs and Bama minipigs.The three ASFVs exhibited similar phenotypes in cell culture,includ‑ing cytopathic efects(CPEs),hemadsorptions(HADs),viral protein expressions and growth curves.Genome sequenc‑ing revealed that all three ASFVs were genotype II strains.Genomic comparisons suggested that the disruption of the viral genes MGF360 and MGF110,rather than EP402R and EP153R,is likely involved in the potential attenuation of ASFV via the upregulation of innate immune responses.展开更多
基金the National Nature Science Foundation of China for Excellent Young Scientists Fund(32222058)Fundamental Research Foundation of CAF(CAFYBB2022QB001).
文摘Developing biomass platform compounds into high value-added chemicals is a key step in renewable resource utilization.Herein,we report porous carbon-supported Ni-ZnO nanoparticles catalyst(Ni-ZnO/AC)synthesized via low-temperature coprecipitation,exhibiting excellent performance for the selective hydrogenation of 5-hydroxymethylfurfural(HMF).A linear correlation is first observed between solvent polarity(E_(T)(30))and product selectivity within both polar aprotic and protic solvent classes,suggesting that solvent properties play a vital role in directing reaction pathways.Among these,1,4-dioxane(aprotic)favors the formation of 2,5-bis(hydroxymethyl)furan(BHMF)with 97.5%selectivity,while isopropanol(iPrOH,protic)promotes 2,5-dimethylfuran production with up to 99.5%selectivity.Mechanistic investigations further reveal that beyond polarity,proton-donating ability is critical in facilitating hydrodeoxygenation.iPrOH enables a hydrogen shuttle mechanism where protons assist in hydroxyl group removal,lowering the activation barrier.In contrast,1,4-dioxane,lacking hydrogen bond donors,stabilizes BHMF and hinders further conversion.Density functional theory calculations confirm a lower activation energy in iPrOH(0.60 eV)compared to 1,4-dioxane(1.07 eV).This work offers mechanistic insights and a practical strategy for solvent-mediated control of product selectivity in biomass hydrogenation,highlighting the decisive role of solvent-catalyst-substrate interactions.
基金supported by National Natural Science Foundation of China(NSFC 52432002,52372041,52302087)Heilongjiang Touyan Team Program,the Fundamental Research Funds for the Central Universities(Grant No.HIT.OCEF.2021003)the Shanghai Aerospace Science and Technology Innovation Fund(SAST2022-60).
文摘Developing effective strategies to regulate graphene’s conduction loss and polarization has become a key to expanding its application in the electromagnetic wave absorption(EMWA)field.Based on the unique energy band structure of graphene,regulating its bandgap and electrical properties by introducing heteroatoms is considered a feasible solution.Herein,metal-nitrogen doping reduced graphene oxide(M–N-RGO)was prepared by embedding a series of single metal atoms M–N_(4) sites(M=Mn,Fe,Co,Ni,Cu,Zn,Nb,Cd,and Sn)in RGO using an N-coordination atom-assisted strategy.These composites had adjustable conductivity and polarization to optimize dielectric loss and impedance matching for efficient EMWA performance.The results showed that the minimum reflection loss(RL_(min))of Fe–N-RGO reaches−74.05 dB(2.0 mm)and the maximum effective absorption bandwidth(EAB_(max))is 7.05 GHz(1.89 mm)even with a low filler loading of only 1 wt%.Combined with X-ray absorption spectra(XAFS),atomic force microscopy,and density functional theory calculation analysis,the Fe–N_(4) can be used as the polarization center to increase dipole polarization,interface polarization and defect-induced polarization due to d-p orbital hybridization and structural distortion.Moreover,electron migration within the Fe further leads to conduction loss,thereby synergistically promoting energy attenuation.This study demonstrates the effectiveness of metal-nitrogen doping in regulating the graphene′s dielectric properties,which provides an important basis for further investigation of the loss mechanism.
基金supported by the Hong Kong Research Grants Council(No.CityU 11201522).
文摘Metal-organic frameworks(MOFs)have been considered as great contender and promising electrode materials for supercapacitors.However,their low capacity,aggregation,and poor porosity have necessitated the exploration of new approaches to enhance the performance of these active materials.In this study,sphere-like MOF were in-situ grown and it subsequently burst,transformed into a desired metal oxide heterostructure comprising n-type ZnO and p-type NiO(ZnO/NiO-350).The resulting optimized flower-like structure,composed of interlaced nanoflakes derived from MOFs,greatly improved the active sites,porosity,and functionality of the electrode materials.The ZnO/NiO-350 electrode exhibited superior electrochemical activities for supercapacitors,compared to the parent MOF,bare n-type,and p-type counterparts.The specific capacitance can reach to 543 F g^(-1) at a current density of 1 A g^(-1).Theoretical modeling and simulations were employed to gain insights into the atomic-scale properties of the materials.Furthermore,an assembled hybrid device using active carbon and ZnO/NiO-350 as electrodes demonstrated excellent energy density of 44 Wh kg^(-1) at a power density of 1.6 Kw kg^(-1).After 5000 cycles at 10 A g^(-1),the cycling stability remained excellent 80%of the initial capacitance.Overall,such evaluation of unique electrode with superior properties may be useful for the next generation supercapacitor electrode.
基金supported by the Hong Kong Research Grants Council(No.CityU 11201522).
文摘The evolution of energy storage technology has seen remarkable progress,with a shift from pure metals to sophisticated,tailor-made active materials.The synthesis of nanostructures with exceptional properties is crucial in the advancement of electrode materials.In this regard,our study highlights the fabrication of a novel,oriented heterostructure comprised of Zn-Mn-Co-telluride grown on a pre-oxidized copper mesh using a hydrothermal method followed by a solvothermal process.This innovative approach leads to the formation of the Zn-Mn-Cotelluride@CuO@Cu heterostructure,which demonstrates the unique oriented morphology.It outperforms both Zn-Mn-Co-telluride@Cu and CuO@Cu by exhibiting lower electrical resistivity,increased redox activity,higher specific capacity,and improved ion diffusion characteristics.The conductivity enhancements of the heterostructure are corroborated by density functional theory(DFT)calculations.When utilized in a hybrid supercapacitor(HSC)alongside activated carbon(AC)electrodes,the Zn-Mn-Co-telluride@CuO@Cu heterostructurebased HSC achieves an energy density of 75.7 Wh kg^(-1).Such findings underscore the potential of these novel electrode materials to significantly impact the design of next-generation supercapacitor devices.
基金This work was supported by the General Program of Natural Science Foundation of Beijing Municipality(project no.9212008).
文摘Objectives Professional identity plays an important role in the long-term development of nurses,and it will change when public health emergency occurs.The objective of this study is to investigate the factors associated with the professional identity of nursing undergraduates in the epidemic of COVID-19.Methods A cross-sectional survey design with convenience sampling was used.A total of 3,875 nursing undergraduates were recruited from seven universities across China from March to April 2020.A general information questionnaire was used to collect students’information,and the Professional Identity Questionnaire for Nurse Students was used to survey their professional identity during the early and later stages of the first wave of the COVID-19 epidemic.Results The score of professional identity in the later stage(59.49±12.41)was higher than that in the early stage(56.96±12.61).The stepwise regression indicated that several factors were associated with professional identity,including gender,residential area,major,impact of the epidemic on intention to work after graduation,reasons for choosing nursing major and students’scores of professional identity in early stage.Conclusions Nursing educators can utilize the positive impact of responding to public health emergencies to increase the professional identity of students.Meanwhile,educators should give those students with lower professional identity more targeted education to cultivate their professional identity after the occurrence of public health emergencies.
基金supported by National Natural Science Foundation of China (NSFC 52372041, 52302087, 51772060, 51672059 and 51621091)Heilongjiang Touyan Team Program+1 种基金the Fundamental Research Funds for the Central Universities (Grant No. HIT.OCEF.2021003)the Shanghai Aerospace Science and Technology Innovation Fund (SAST2022-60)。
文摘Polarization and conductance losses are the fundamental dielectric attenuation mechanisms for graphene-based absorbers, but it is not fully understood in revealing the loss mechanism of affect graphene itself. For the first time, the reduced graphene oxide(RGO) based absorbers are developed with regulatory absorption properties and the absorption mechanism of RGO is mainly originated from the carrier injection behavior of trace metal Fe nanosheets on graphene. Accordingly, the minimum reflection loss(RLmin) of Fe/RGO-2composite reaches-53.38 dB(2.45 mm), and the effective absorption bandwidth achieves 7.52 GHz(2.62 mm) with lower filling loading of 2 wt%. Using off-axis electron hologram testing combined with simulation calculation and carrier transport property experiments, we demonstrate here the carrier injection behavior from Fe to graphene at the interface and the induced charge accumulation and rearrangement, resulting in the increased interfacial and dipole polarization and the conductance loss. This work has confirmed that regulating the dielectric property of graphene itself by adding trace metals can not only ensure good impedance matching, but also fully exploit the dielectric loss ability of graphene at low filler content,which opens up an efficient way for designing lightweight absorbers and may be extended to other types materials.
基金supported by National Natural Science Foundation of China (Grant Nos. 51728204 and 51772272)Fundamental Research Funds for the Central Universities (Grant No. 2018QNA4011)+2 种基金Qianjiang Talents Plan D (QJD1602029)Startup Foundation for Hundred-Talent Program of Zhejiang Universitythe Fundamental Research Funds for the Central Universities (2015XZZX010-02)
文摘For efficient electrolysis of water for hydrogen generation or other valueadded chemicals, it is highly relevant to develop low-temperature synthesis of low-cost and high-e ciency metal sulfide electrocatalysts on a large scale. Herein, we construct a new core–branch array and binder-free electrode by growing Ni_3S_2 nanoflake branches on an atomic-layer-deposited(ALD) TiO_2 skeleton. Through induced growth on the ALD-TiO_2 backbone, cross-linked Ni_3S_2 nanoflake branches with exposed { 210} highindex facets are uniformly anchored to the preformed TiO_2 core forming an integrated electrocatalyst. Such a core–branch array structure possesses large active surface area, uniform porous structure, and rich active sites of the exposed { 210 } high-index facet in the Ni_3S_2 nanoflake. Accordingly, the TiO_2@Ni_3S_2 core/branch arrays exhibit remarkable electrocatalytic activities in an alkaline medium, with lower overpotentials for both oxygen evolution reaction(220 mV at 10 mA cm^(-2)) and hydrogen evolution reaction(112 m V at 10 mA cm^(-2)), which are better than those of other Ni_3S_2 counterparts. Stable overall water splitting based on this bifunctional electrolyzer is also demonstrated.
基金supported by the National Natural Science Foundation of China (Grant No. 51728204, 51502263, 51772272)Fundamental Research Funds for the Central Universities (2018QNA4011)+2 种基金Qianjiang Talents Plan D (QJD1602029)Program for Innovative Research Team in University of Ministry of Education of China (IRT13037)Startup Foundation for Hundred-Talent Program of Zhejiang University
文摘Rational design of cost-effective high-performance electrocatalysts for oxygen evolution reaction (OER) is of great significance for electrochemical water splitting. Herein, we adopt a nitrogen doping method to fabricate self-supported N-doped CoO nanowire arrays (N-CoO) as active electrocatalysts via a facile hydrothermal combined doping method. The N-CoO nanowires are strongly composited with the carbon cloth substrate forming free-standing electrode with reinforced stability and high electronic conductivity. Owing to the increased accessible and electroactive areas, rich/short pathways for charge transfer and enhanced electronic conductivity, the N-CoO electrode exhibits excellent electrocatalytic performance for OER with a low overpotential (319 mV at 10 mA cm^-2 and 410 mV at 100 mA cm^-2) and a low Tafel slope of 74 mV dec^-1 as well as superior long-term stability with no decay in 24 h continuous test in alkaline solution. Our reported design and optimization strategy provide a promising way to construct interesting well-aligned arrays for application in energy storage and conversion.
基金supported by the National Natural Science Foundation of China(51772272,51502263,51728204)the Fundamental Research Funds for the Central Universities(2018QNA4011)+2 种基金Qianjiang Talents Plan of Zhejiang Province(QJD1602029)the Program for Innovative Research Team in University of Ministry of Education of China(IRT13037)the Startup Foundation for Hundred-Talent Program of Zhejiang University~~
文摘It is important but challenging to design and fabricate an efficient and cost-effective electrocatalyst for the oxygen evolution reaction(OER). Herein, we report free-standing 3 D nickel arrays with a cross-linked porous structure as interesting and high-performance electrocatalysts for OER via a facile one-step electrodeposition method. The 3 D nickel arrays are strongly anchored on the substrate, forming self-supported electrocatalysts with reinforced structural stability and high electrical conductivity. Because of their increased active surface area, abundant channels for electron/ion transportation and enhanced electronic conductivity, the designed 3 D nickel arrays exhibit superior electrocatalytic OER performance with a low overpotential(496 mV at 50 mA cm–2) and a small Tafel slope(43 mV dec–1) as well as long-term stability(no decay after 24 h) in alkaline solution. Our proposed rational design strategy may open up a new way to construct other advanced 3 D porous materials for widespread application in electrocatalysis.
基金supported by National Natural Science Foundation of China(Nos.51728204 and 51772272)Fundamental Research Funds for the Central Universities(2018QNA4011)+1 种基金Qianjiang Talents Plan D(QJD1602029)Startup Foundation for Hundred-Talent Program of Zhejiang University
文摘Controllable synthesis of highly active micro/nanostructured metal electrocatalysts for oxygen evolution reaction(OER) is a particularly significant and challenging target.Herein,we report a 3D porous sponge-like Ni material,prepared by a facile hydrothermal method and consisting of cross-linked micro/nanofibers,as an integrated binder-free OER electrocatalyst.To further enhance the electrocatalytic performance,an N-doping strategy is applied to obtain N-doped sponge Ni(N-SN) for the first time,via NH3 annealing.Due to the combination of the unique conductive sponge structure and N doping,the as-obtainedN-SN material shows improved conductivity and a higher number of active sites,resulting in enhanced OER performance and excellent stability.Remarkably,N-SN exhibits a low overpotential of 365 mV at 100 mA cm-2 and an extremely small Tafel slope of 33 mV dec-1,as well as superior long-term stability,outperforming unmodified sponge Ni.Importantly,the combination of X-ray photoelectron spectroscopy and near-edge X-ray adsorption fine structure analyses shows that γ-NiOOH is the surface-active phase for OER.Therefore,the combination of conductive sponge structure and N-doping modification opens a new avenue for fabricating new types of high-performance electrodes with application in electrochemical energy conversion devices.
基金This work was supported by the Donations for Research Projects_RMGS(project number 9229006)M.A.A.expresses appreciation to the Deanship of Scientific Research at King Khalid University Saudi Arabia(R.G.P.2/40/43).
文摘Human civilization has been relentlessly inspired by the nurturing lessons;nature is teaching us.From birds to airplanes and bullet trains,nature gave us a lot of perspective in aiding the progress and development of countless industries,inventions,transportation,and many more.Not only that nature inspired us in such technological advances but also,nature stimulated the advancement of micro-and nanostructures.Nature-inspired nanoarchitectures have been consid-ered a favorable structure in electrode materials for a wide range of applications.It offers various positive attributes,especially in energy storage applications,such as the formation of hierarchical two-dimen-sional and three-dimensional interconnected networked structures that benefit the electrodes in terms of high surface area,high porosity and rich surface textural features,and eventually,delivering high capacity and outstanding overall material stability.In this review,we compre-hensively assessed and compiled the recent advances in various nature-inspired based on animal-and human-inspired nanostructures used for supercapacitors.This comprehensive review will help researchers to accommodate nature-inspired nanostructures in industrializing energy storage and many other applications.
基金supports from the Basic Research Project of the Science and Technology Innovation Commission of Shenzhen (No. JCYJ20200109141640095)the Shenzhen Key Laboratory of Interfacial Science and Engineering of Materials (No. ZDSYS20200421111401738)+3 种基金the Leading Talents of Guangdong Province Program (No. 2016LJ06C536)the GuangdongHong Kong-Macao Joint Laboratory (No. 2019B121205001)the National Natural Science Foundation of China (No. 21875097)the support from the Hong Kong Research Grants Council (Project number CityU 11218420)。
文摘Organic active units often transform into radical intermediates during the redox processes but exhibit poor cycling stability due to the uncontrollable redox of the radicals. Herein, we report a facile and efficient strategy to modulate the molecular orbital energies, charge transport capacities, and spin electron densities of the active units in covalent organic frameworks(COFs) via regulating the conjugated unit size to optimize the redox activity and stability of the organic radicals. COFs based on different imide conjugated units exhibit tunable discharge voltages, rate performance and cycling stabilities. Detailed characterizations and theoretical calculation reveal that imide radicals are the important active intermediates during the redox processes of these COFs. Specifically, increasing the size of the imide conjugated units could effectively delocalize the radical electrons and improve the stability of the COFs electrodes. This study offers a very effective strategy to modulate the redox chemistry of organic materials for electrochemical energy storage.
基金supported by the National Natural Science Foundation of China (grant no. 51728204, 51772272 and 51502263)Qianjiang Talents Plan D (grant. no. QJD1602029)+2 种基金the Startup Foundation for Hundred-Talent Program of Zhejiang Universitysupport by the Program for Innovative Research Team in University of Ministry of Education of China (IRT13037)the Key Science and Technology Innovation Team of Zhejiang Province (2010R50013)
文摘Rational design of advanced cost-effective electrocatalysts is vital for the development of water electrolysis. Herein, we report a novel binder-free efficient CoS@CoOcore/shell electrocatalysts for oxygen evolution reaction（OER） via a combined hydrothermal-sulfurization method. The sulfurized net-like CoSnanoflakes are strongly anchored on the CoOnanowire core forming self-supported binder-free core/shell electrocatalysts. Positive advantages including larger active surface area of CoSnanoflakes,and reinforced structural stability are achieved in the CoS@CoOcore/shell arrays. The OER performances of the CoS@CoOcore/shell arrays are thoroughly tested and enhanced electrocatalytic performance with lower over-potential(260 m V at 20 m A cm) and smaller Tafel slopes（56 mV dec-1） as well as long-term durability are demonstrated in alkaline medium. Our proposed core/shell smart design may provide a new way to construct other advanced binder-free electrocatalysts for applications in electrochemical catalysis.
文摘In the original publication,Figure S4 is an ancillary image to compare the specific surface areas of TiO2/Ni3S2 and Ni3S2 samples and it was incorrectly published.To better serve our readers,the correct figure is provided in this correction.The BET values are correct and unaffected.The corresponding figure caption,data analysis and conclusions are not affected and thus not to be changed.The authors would like to apologize for any inconvenience caused.
基金Supported by the National Natural Science Foundation of China(21202066)the Natural Science Foundation of Yunnan Province,China(2012FB156)+1 种基金the Scientific Research Foundation of Department of Education of Yunnan Province,China(2013C247)the Open Research Foundation of Yunnan Key Laboratory of Pharmacology for Natural Products(2013G009)
文摘This study aimed to investigate the chemical constituents from the flowers of Dendrobium chrysanthum and determine its bioactive compounds. [Method] The compounds were extracted by 95% alcohol and isolated by column chromatography on silica gel and Sephadex LH-20. Their structures were identified by spectroscopic analysis （1H NMR, 13CNMR and ElMS）. [Result] Nine compounds were obtained and identified as stigmasterol , β-sitosterol , linoleic acid , stigmast-4-en-3-one , dibutyl phthalate , moscatilin , ergosterol , ergosterol peroxide and daucosterol . [Conclusion] Al compounds were isolated from its flowers for the first time.
基金support by the Anusandhan National Research Foundation(ANRF),Department of Science&Technology(DST),New Delhi,India under Ramanujan award(SB/S2/RJN-159/2017)Hussain and K.Zhang acknowledge financial support by the Hong Kong Research Grants Council(project number CityU 11201522).
文摘MXenes(inorganic metal carbides,nitrides,and carbonitrides)are currently the rising star of two-dimensional(2D)family.After its discovery in 2011,initial research was concentrated on pristine MXenes only.However,in the last few years,the MXene family has been expanded with the exploration of novel double MXenes,synthesis of non-Ti MXenes,and heteroatom doping of MXenes.The current review article delivers an exclusive overview of the current research trends on the heteroatom doping of MXenes.The recent advances in heteroatom doping of MXenes(majorly Ti-MXenes)for energy storage/conversion applications including secondary batteries(Li-ion,Li–S,Na–S,Na-ion,K-ion,Zn-ion batteries),supercapacitors,electrocatalysis,etc.are summarized.A brief overview of the defects as well as doping in various 2D materials is included in the manuscript.Various doping strategies of MXenes are outlined.Moreover,the impact of artificial intelligence/machine learning on MXene research is also concisely discussed.Additionally,the advantages of doping on MXenes are discussed in detail.Lastly,the existing challenges and future prospects of doped MXenes are addressed.It is expected that the current review will open new prospects for the fabrication of advanced energy devices through heteroatom doping of MXenes.
基金supported by the Hong Kong Research Grants Council(Project Number CityU 11218420)the Deanship of Scientific Research at King Khalid University Saudi Arabia for funding through research groups program under Grant Number R.G.P.2/593/44.
文摘MXene has garnered widespread recognition in the scientific com-munity due to its remarkable properties,including excellent thermal stability,high conductivity,good hydrophilicity and dispersibility,easy processability,tunable surface properties,and admirable flexibility.MXenes have been categorized into different families based on the number of M and X layers in M_(n+1)X_(n),such as M_(2)X,M_(3)X_(2),M_(4)X_(3),and,recently,M_(5)X_(4).Among these families,M_(2)X and M_(3)X_(2),par-ticularly Ti_(3)C_(2),have been greatly explored while limited studies have been given to M_(5)X_(4)MXene synthesis.Meanwhile,studies on the M_(4)X_(3)MXene family have developed recently,hence,demanding a compilation of evaluated studies.Herein,this review provides a systematic overview of the latest advancements in M_(4)X_(3)MXenes,focusing on their properties and applications in energy storage devices.The objective of this review is to provide guidance to researchers on fostering M_(4)X_(3)MXene-based nanomaterials,not only for energy storage devices but also for broader applications.
基金supported by the National Natural Science Foun-dation of China(21776026,22078023)Liaoning Revitalization Talents Program(XLYC1902037).
文摘Low cost processing of lignocellulosic biomass is of great importance for sustainable chemistry and engineering.Herein,a low cost system composed of 1-butyl-3-methylimidazolium chloride([C_(4)C_(1) im]Cl),HCl and formaldehyde(FA)was developed for the pretreatment of corn stalk at 80℃.The efficiency of this technology was compared with that in dioxane system or without FA addition.Due to FA stabilization,the extent of acid-hydrolysis of carbohydrate fraction can be significantly decreased while 70%above of lignin was removed with the pretreatment of[C_(4)C_(1) im]Cl/HCl/FA system at 80℃for 2 h.A maximum reducing sugar yield of 93.7%and glucose concentration of 7.0 mg·ml^(-1) were subsequently obtained from enzymatic hydrolysis of the slurry.There were great differences in compositions of small molecule degraded products obtained with FA addition or not.The present[C_(4)C_(1) im]C_(l) based system exhibits great potential of substituting volatile organic solvents(i.e.dioxane)in developing low cost lignocellulosic biomass pretreatment at low temperature.Also,this work would gain insight into understanding on the roles of stabilization methods on the economic improvement of IL based biomass processing.
基金supported by the National Key Research and Develop‑ment Program of China under Grant[2021YFD1800105]the Jiangsu Provincial Key R&D Plan under Grant[BE2020398]+3 种基金the Jiangsu Agricultural Science and Technology Independent Innovation Fund Project under Grant[CX(21)2035]the 111 Project under Grant D18007the A Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)supported by Research and Practice Innovation Project of Jiangsu Province Graduate Students(SJCX24_2310).
文摘African swine fever(ASF)is an acute and fatal hemorrhagic disease in domestic pigs and wild boars caused by African swine fever virus(ASFV)that currently threatens the pig industry worldwide.Since the 2018 ASF outbreak in China,ASFV has evolved and caused diverse clinical manifestations,such as chronic and asymptomatic infections.Therefore,it is important to understand the molecular mechanisms underlying ASFV attenuation in the feld.Here,we isolated three ASFVs from one diseased and two asymptomatic pigs by using primary porcine alveolar macrophages(PAMs)from both domestic pigs and Bama minipigs.The three ASFVs exhibited similar phenotypes in cell culture,includ‑ing cytopathic efects(CPEs),hemadsorptions(HADs),viral protein expressions and growth curves.Genome sequenc‑ing revealed that all three ASFVs were genotype II strains.Genomic comparisons suggested that the disruption of the viral genes MGF360 and MGF110,rather than EP402R and EP153R,is likely involved in the potential attenuation of ASFV via the upregulation of innate immune responses.
