Developing low-cost, high-performance catalysts is of fundamental significance for electrochemical energy conversion and storage. In recent years, metal@carbon core@shell nanocomposites have emerged as a unique class ...Developing low-cost, high-performance catalysts is of fundamental significance for electrochemical energy conversion and storage. In recent years, metal@carbon core@shell nanocomposites have emerged as a unique class of functional nanomaterials that show apparent electrocatalytic activity towards a range of reactions, such as hydrogen evolution reaction, oxygen evolution reaction, oxygen reduction reaction, and CO2 reduction reaction, that are important in water splitting, fuel cells and metal-air batteries. The activity is primarily attributed to interfacial charge transfer from the metal core to the carbon shell that manipulate the electronic interactions between the catalyst surface and reaction intermediates, and varies with the structures and morphologies of the metal core(elemental composition, core size, etc.) and carbon shell(doping,layer thickness, etc.). Further manipulation can be achieved by the incorporation of a third structural component. A perspective is also included highlighting the current gap between theoretical modeling and experimental results, and technical challenges for future research.展开更多
A nano sulfur-based composite cathode material featured by uniform core@shell-structured sulfur@polypyrrole nanoparticles sandwiched in three-dimensional graphene sheets conductive network(S@PPy/GS) is fabricated vi...A nano sulfur-based composite cathode material featured by uniform core@shell-structured sulfur@polypyrrole nanoparticles sandwiched in three-dimensional graphene sheets conductive network(S@PPy/GS) is fabricated via a facile solution-based method. The S@PPy nanoparticles are synthesized by in situ chemical oxidative polymerization of pyrrole on the surface of sulfur particles,and then graphene sheets are covered outside the S@PPy nanoparticles,forming a three-dimensional conductive network. When evaluating the electrochemical performance of S@PPy/GS in a lithium–sulfur battery,it delivers large discharge capacity,excellent cycle stability,and good rate capability. The initial discharge capacity is up to 1040 m Ah/g at 0.1 C,the capacity can remain 537.8 m Ah/g at 0.2 C after 200 cycles,even at a higher rate of 1 C,the specific capacity still reaches 566.5 m Ah/g. The good electrochemical performance is attributed to the unique structure of S@PPy/GS,which can not only provide an excellent transport of lithium and electron ions within the electrodes,but also retard the shuttle effect of soluble lithium polysulfides effectively,thus plays a positive role in building better lithium-sulfur batteries.展开更多
Bare Pd metal nanoparticles invariably suffer from poor selectivity in furfural hydrogenation by forming flat configurations,with the aromatic ring of the substrate molecules parallel to the metal surface.Herein,we pu...Bare Pd metal nanoparticles invariably suffer from poor selectivity in furfural hydrogenation by forming flat configurations,with the aromatic ring of the substrate molecules parallel to the metal surface.Herein,we put forward a promising solution by using CeO_(2)as promoters to modify Pd nanoparticles for modulating the adsorption behaviors of furfural molecules.To achieve the highly-desired ultra-small Pd@CeO_(2)core@shell nanostructure,a“constrained auto-redox”synthesis is developed,in which silicalite-1 supports play the key role of providing their surface as the landing place of PdO_(x)precursors for inhibiting the overgrowth and the deformation.To the best of our knowledge,this is one of the smallest core@shell materials obtained from aqueous synthesis.When evaluated as catalysts,Pd@CeO_(2)/S-1 gives 98.9%conversion of furfural with 94.3%selectivity for furfural alcohol in 15 h,which is much better than that of Pd/S-1(88.6%conversion with 44.3%selectively).The DFT simulation reveals a strong interaction between the defects of CeO_(2)and the oxygen atom of the–CHO group in furfural molecules,which benefits the selective hydrogenation occurred in the–CHO group rather than the furan ring.展开更多
It is well recognized that interfacial effect and/or impedance matching play a great impact on microwave absorption.Herein,we proposed a facile strategy to take full advantage of interface engineering and impedance ma...It is well recognized that interfacial effect and/or impedance matching play a great impact on microwave absorption.Herein,we proposed a facile strategy to take full advantage of interface engineering and impedance matching for boosting microwave absorption performance(MAPs).Three-dimensional(3D)hierarchical urchin-like core@shell structured NiO/Ni@CNTs multicomponent nanocomposites(MCNCs)were elaborately constructed and produced in high efficiency through a facile continuous chemical bath deposition,thermal treatment,and catalytic chemical vapor decomposition process.By controlling the pyrolysis time,the NiO/Ni@CNTs urchin-like MCNCs with different lengths and aggregation degrees of CNTs could be selectively synthesized.The obtained results revealed that the enhanced CNT contents provided abundant interfaces and effectively aggrandized their interfacial effects,which resulted in improved polarization loss,conductivity loss,and comprehensive MAPs.Impressively,the interfaces and impedance matching in the designed NiO/Ni@CNTs urchin-like MCNCs could be optimized by regulating the pyrolysis temperature,which further improved the comprehensive MAPs.And the designed NiO/Ni@CNTs urchin-like MCNCs could simultaneously display strong absorption capabilities,broad absorption bandwidths,and thin matching thicknesses.Therefore,our findings not only provided a simple and universal approach to produce core@shell structured magnetic carbon-based urchin-like MCNCs but also presented an interface engineering and impedance matching strategy to develop the tunable,strong absorption,broadband,lightweight high-efficiency microwave absorbers.展开更多
Previous results revealed that the defect and/or interface had a great impact on the electromagnetic pa-rameters of materials.In order to understand the main physical mechanisms and effectively utilize these strategie...Previous results revealed that the defect and/or interface had a great impact on the electromagnetic pa-rameters of materials.In order to understand the main physical mechanisms and effectively utilize these strategies,in this study,M Fe_(2)O_(4)and flower-like core@shell M Fe_(2)O_(4)@MoS_(2)(M=Mn,Ni,and Zn)sam-ples with different categories were elaborately designed and selectively produced in large scale through a simple two-step hydrothermal reaction.We conducted the systematical investigation on their microstruc-tures,electromagnetic parameters and microwave absorption performances(MAPs).The obtained results revealed that the large radius of M^(2+)cation could effectively boost the concentration of oxygen vacancy in the M Fe_(2)O_(4)and M Fe_(2)O_(4)@MoS_(2)samples,which resulted in the improvement of dielectric loss capabil-ities and MAPs.Furthermore,the introduction of MoS_(2)nanosheets greatly improved the interfacial effect and enhanced the polarization loss capabilities,which also boosted the MAPs.By taking full advantage of the defect and interface,the designed M Fe_(2)O_(4)@MoS_(2)samples displayed tunable and excellent com-prehensive MAPs including strong absorption capability,wide absorption bandwidth and thin matching thicknesses.Therefore,the clear understanding of defect and interface engineering made these strategies well elaborately designed and applicable to improving MAPs.展开更多
Due to the good manipulation of electronic structure and defect,anion regulating should be a promising strategy to regulate the electromagnetic(EM)parameters and optimize the EM wave absorption performances(EMWAPs).In...Due to the good manipulation of electronic structure and defect,anion regulating should be a promising strategy to regulate the electromagnetic(EM)parameters and optimize the EM wave absorption performances(EMWAPs).In this work,we proposed a facile route for the large-scale production of core@shell structured hollow carbon spheres@MoSxSe_(2−x)(x=0.2,0.6,and 1.0)multicomponent nanocomposites(MCNCs)through a mild template method followed by hydrothermal process.The obtained results revealed that the designed hollow carbon spheres@MoSxSe_(2−x)MCNCs presented the improved sulfur vacancy concentration by regulating the x value from 0.2 to 1.0.The obtained hollow carbon spheres@MoSxSe_(2−x)MCNCs displayed the extraordinary comprehensive EMWAPs because of the introduced abundant defects and excellent interfacial effects.Furthermore,the as-prepared hollow carbon spheres@MoSxSe_(2−x)MCNCs presented the progressively improved comprehensive EMWAPs with the x value increasing from 0.2 to 1.0,which could be explained by their boosted polarization loss abilities and impedance matching characteristics originating from the enhanced sulfur vacancy concentration.Therefore,our findings not only demonstrated that the anion regulating was a promising method to optimize EM parameters and EMWAPs,but also provided a facile route to design the transition metal dichalcogenides-based MCNCs as the much more attractive candidates for highperformance microwave absorbers.展开更多
The design of electrocatalysts with enhanced adsorption and activation of nitrogen(N2)is critical for boosting the electrochemical N2reduction(ENR).Herein,we developed an efficient strategy to facilitate N2 adsorption...The design of electrocatalysts with enhanced adsorption and activation of nitrogen(N2)is critical for boosting the electrochemical N2reduction(ENR).Herein,we developed an efficient strategy to facilitate N2 adsorption and activation for N2 electroreduction into ammonia(NH3)by vacancy engineering of core@shell structured Au@Sn O2 nanoparticles(NPs).We found that the ultrathin amorphous SnO2 shell with enriched oxygen vacancies was conducive to adsorb N2as well as promoted the N2 activation,meanwhile the metallic Au core ensured the good electrical conductivity for accelerating electrons transport during the electrochemical N2 reduction reaction,synergistically boosting the N2 electroreduction catalysis.As confirmed by the15N-labeling and controlled experiments,the core@shell Au@amorphous SnO2 NPs with abundant oxygen vacancies show the best performance for N2 electroreduction with the NH3 yield rate of 21.9 lg h-1mg-1catand faradaic efficiency of 15.2%at-10.2 VRHE,which surpass the Au@crystalline SnO2 NPs,individual Au NPs and all reported Au-based catalysts for ENR.展开更多
The Pt-Ni nanoframe catalysts have attracted great interest owing to their unique electronic structure and excellent catalytic performance. However, the stability of the tenu ous edges of nano frame-structures is diss...The Pt-Ni nanoframe catalysts have attracted great interest owing to their unique electronic structure and excellent catalytic performance. However, the stability of the tenu ous edges of nano frame-structures is dissatisfactory and their un iversal applicati ons in catalytic market beyond electrocatalytic reactions are yet to be tapped and explored. Herein, we developed a new core@ shell structured Pt-Ni nanoframe@CeO2 (Pt-Ni NF@CeO2) composite via etching the Ni from inhomogeneous Pt-Ni rhombic dodecahedra (Pt-Ni RD) by cerium(lll) acetate hydrate (Ce(OAc)3). In this path, Pt-Ni RD was used as self-sacrificial 怕mplate, while the Ce(OAc)3 serves as the provider of the Ce3* source and OH' for the formation of CeO2 shell, etchant of Pt-Ni RD, and the surface modification agent. By this way, the etching of Pt-Ni RD and the formation of the CeO2 shell are simultaneously proceeded to form the final Pt-Ni NF@CeO2 in one step. The obtained Pt-Ni NF@CeO2 exhibits strong in terfacial charge tran sfer interactio n betwee n Pt-Ni NF core and CeO2 shell eve n without reductio n treatment, leading to enhan ced catalytic activity in the hydrogenation of phenylacetylene. After introduction of trace silver, the Pt-Ni-Ag4.9 NF@CeO2 achieves remarkable catalytic performa nee for the selective con versi on of phe ny lacetyle ne to styrene: high con version (100%), styre ne selectivity (86.5%), and good stability. It reveals that enc apsulatio n n oble metal nano frames into metal oxide to form core @ shell structured hybrids will in deed enhance their stability and catalytic properties. Particularly, this work expends the application of noble metal nanoframes materials to hydrogenation reacti ons.展开更多
Defect and interface engineering are efficient approaches to adjust the physical and chemical properties of nanomaterials.In order to effectively utilize these strategies for the improvement of microwave absorption pr...Defect and interface engineering are efficient approaches to adjust the physical and chemical properties of nanomaterials.In order to effectively utilize these strategies for the improvement of microwave absorption properties(MAPs),in this study,we reported the synthesis of hollow carbon shells and hollow carbon@MoS_(2)nanocomposites by the template-etching and templateetching-hydrothermal methods,respectively.The obtained results indicated that the degree of defect for hollow carbon shells and hollow carbon@MoS_(2)could be modulated by the thickness of hollow carbon shell,which effectively fulfilled the optimization of electromagnetic parameters and improvement of MAPs.Furthermore,the microstructure investigations revealed that the precursor of hollow carbon shells was encapsulated by the sheet-like MoS_(2)in high efficiency.And the introduction of MoS_(2)nanosheets acting as the shell effectively improved the interfacial effects and boosted the polarization loss capabilities,which resulted in the improvement of comprehensive MAPs.The elaborately designed hollow carbon@MoS_(2)samples displayed very outstanding MAPs including strong absorption capabilities,broad absorption bandwidth,and thin matching thicknesses.Therefore,this work provided a viable strategy to improve the MAPs of microwave absorbers by taking full advantage of their defect and interface engineering.展开更多
In this work,we put forward a scheme to exquisitely design and selectively synthesize the core@shell structured MSe_(2)/FeSe_(2)@MoSe_(2)(M=Co,Ni)flower-like multicomponent nanocomposites(MCNCs)through a simple two-st...In this work,we put forward a scheme to exquisitely design and selectively synthesize the core@shell structured MSe_(2)/FeSe_(2)@MoSe_(2)(M=Co,Ni)flower-like multicomponent nanocomposites(MCNCs)through a simple two-step hydrothermal reaction on the surfaces of MFe_(2)O_4 nanospheres with the certain amounts of Mo and Se sources.With increasing the amounts of Mo and Se sources,the obtained core@shell structured MSe_(2)/FeSe_(2)@MoSe_(2)(M=Co,Ni)MCNCs with the enhanced content of MoSe_(2)and improved flower-like geometry morphology could be produced on a large scale.The obtained results revealed that the as-prepared samples displayed improved comprehensive microwave absorption properties(CMAPs)with the increased amounts of Mo and Se sources.The as-prepared CoSe_(2)/FeSe_(2)@MoSe_(2)and NiSe_(2)/FeSe_(2)@MoSe_(2)MCNCs with the well-defined flower-like morphology could simultaneously present the outstanding CMAPs in terms of strong absorption capability,wide absorption bandwidth,and thin matching thicknesses,which mainly originated from the conduction loss and flower-like geometry morphology.Therefore,the findings not only develop the very desirable candidates for high-performance microwave absorption materials but also pave a new way for optimizing the CMAPs through tailoring morphology engineering.展开更多
In this study, Co3O4@CeO2 core@shell nanowires were successfully prepared via thermal decomposition of Co(CO3)0.5(OH).0.11H2O@CeO2 core@shell nanowire precursors. As a CO oxidation catalyst, Co3O4@CeO2 shows remar...In this study, Co3O4@CeO2 core@shell nanowires were successfully prepared via thermal decomposition of Co(CO3)0.5(OH).0.11H2O@CeO2 core@shell nanowire precursors. As a CO oxidation catalyst, Co3O4@CeO2 shows remarkably enhanced catalytic performance compared to Co3O4 nanowires and CeO2 nanoparticles (NPs), indicating obvious synergistic effects between the two components. It also suggests that the CeO2 shell coating can effectively prevent Co3O4 nanowires from agglomerating, hence effecting a substantial improvement in the structural stability of the Co3O4 catalyst. Furthermore, the fabrication of the welbdisperse4 core@shell structure results in a maximized interface area between Co3O4 and CeO2, as well as a reduced Co3O4 size, which may be responsible for the enhanced catalytic activity of Co3O4@CeO2. Further examination revealed that CO oxidation may occur at the interface of Co3O4 and CeO2. The influence of calcination temperatures and the component ratio between Co3O4 and CeO2 were then investigated in detail to determine the catalytic performance of Co3O4@CeO2 core@shell nanowires, the best of which was obtained by calcination at 250 ℃ for 3 h with a Ce molar concentration of about 38.5%. This sample achieved 100% CO conversion at a reduced temperature of 160 ℃. More importantly, more than 2.5 g of the Co3O4@CeO2 core@shell nanowires were produced in one pot by this simple process, which may be beneficial for practical applications as automobile-exhaust gas-treatment catalysts.展开更多
Rational design and construction of low-cost and highly efficient electrocatalysts for hydrogen evolution reaction(HER)is meaningful but challenging.Herein,a robust three dimensional(3D)hollow CoSe_(2)@ultrathin MoSe_...Rational design and construction of low-cost and highly efficient electrocatalysts for hydrogen evolution reaction(HER)is meaningful but challenging.Herein,a robust three dimensional(3D)hollow CoSe_(2)@ultrathin MoSe_(2)core@shell heterostructure(CoSe_(2)@MoSe_(2))is proposed as an efficient HER electrocatalyst through interfacial engineering.Benefitting from the abundant heterogeneous interfaces on CoSe_(2)@MoSe_(2),the exposed edge active sites are maximized and the charge transfer at the hetero-interfaces is accelerated,thus facilitating the HER kinetics.It exhibits remarkable performance in pH-universal conditions.Notably,it only needs an overpotential(η10)of 108 mV to reach a current density of 10 mA·cm^(-2)in 1.0 M KOH,outperforming most of the reported transition metal selenides electrocatalysts.Density functional theory(DFT)calculations unveil that the heterointerfaces synergistically optimize the Gibbs free energies of H2O and H^(*)during alkaline HER,accelerating the reaction kinetics.The present work may provide new construction guidance for rational design of high-efficient electrocatalysts.展开更多
We report the synthesis of one-dimensional(1-D)magnetic Fe_(2)P nanowires and Fe_(2)P@C core@shell nanocables by the reactions of triphenylphosphine(PPh_(3))with Fe powder(particles)and ferrocene(Fe(C_(5)H_(5))_(2)),r...We report the synthesis of one-dimensional(1-D)magnetic Fe_(2)P nanowires and Fe_(2)P@C core@shell nanocables by the reactions of triphenylphosphine(PPh_(3))with Fe powder(particles)and ferrocene(Fe(C_(5)H_(5))_(2)),respectively,in vacuum-sealed ampoules at 380-400℃.The synthesis is based on chemical conversion of micrometer or nanometer sized Fe particles into Fe_(2)P via the extraction of phosphorus from liquid PPh_(3) at elevated temperatures.In order to control product diameters,a convenient sudden-temperature-rise strategy is employed,by means of which diameter-uniform Fe_(2)P@C nanocables are prepared from the molecular precursor Fe(C_(5)H_(5))2.In contrast,this strategy gives no obvious control over the diameters of the Fe_(2)P nanowires obtained using elemental Fe as iron precursor.The formation of 1-D Fe_(2)P nanostructures is ascribed to the cooperative effects of the kinetically induced anisotropic growth and the intrinsically anisotropic nature of hexagonal Fe_(2)P crystals.The resulting Fe_(2)P nanowires and Fe_(2)P@C nanocables display interesting ferromagnetic-paramagnetic transition behaviors with blocking temperatures of 230 and 268 K,respectively,significantly higher than the ferromagnetic transition temperature of bulk Fe_(2)P(TC=217 K).展开更多
化工、纺织印染与农药化肥等产业的蓬勃发展推动着人类社会的进步,但同时也给环境治理带来了巨大难题。目前,光催化降解局限于在特定波长下针对单一有机污染物进行降解,然而现实中的情况往往更复杂。因此,开发一种多功能光催化材料用于...化工、纺织印染与农药化肥等产业的蓬勃发展推动着人类社会的进步,但同时也给环境治理带来了巨大难题。目前,光催化降解局限于在特定波长下针对单一有机污染物进行降解,然而现实中的情况往往更复杂。因此,开发一种多功能光催化材料用于光催化降解不同有机污染物显得尤为重要。采用一步无模板溶剂热法合成了核壳结构的C-TiO_(2)复合材料前驱体,并在氩气气氛下煅烧得到高结晶度的C-TiO_(2)复合光催化材料。运用SEM、TEM、XRD和TG等表征手段对材料进行表征,结论如下:550℃煅烧时的样品为包含少量碳的高结晶度的锐钛矿相TiO 2,且550℃煅烧时的样品依然保持了完整的核壳结构。此外,C-TiO_(2)复合材料的比表面积高达85.69 m 2·g^(-1),平均孔径为16.4 nm以及孔体积为0.423 m 3·g^(-1)。在UV-Vis光照射下,C-TiO_(2)复合材料分别对罗丹明B(RhB)、亚甲基蓝(MB)和刚果红(CR)3种染料显示出增强的光催化降解活性。展开更多
基金National Science Foundation (CHE1710408) for partial support of the work
文摘Developing low-cost, high-performance catalysts is of fundamental significance for electrochemical energy conversion and storage. In recent years, metal@carbon core@shell nanocomposites have emerged as a unique class of functional nanomaterials that show apparent electrocatalytic activity towards a range of reactions, such as hydrogen evolution reaction, oxygen evolution reaction, oxygen reduction reaction, and CO2 reduction reaction, that are important in water splitting, fuel cells and metal-air batteries. The activity is primarily attributed to interfacial charge transfer from the metal core to the carbon shell that manipulate the electronic interactions between the catalyst surface and reaction intermediates, and varies with the structures and morphologies of the metal core(elemental composition, core size, etc.) and carbon shell(doping,layer thickness, etc.). Further manipulation can be achieved by the incorporation of a third structural component. A perspective is also included highlighting the current gap between theoretical modeling and experimental results, and technical challenges for future research.
文摘A nano sulfur-based composite cathode material featured by uniform core@shell-structured sulfur@polypyrrole nanoparticles sandwiched in three-dimensional graphene sheets conductive network(S@PPy/GS) is fabricated via a facile solution-based method. The S@PPy nanoparticles are synthesized by in situ chemical oxidative polymerization of pyrrole on the surface of sulfur particles,and then graphene sheets are covered outside the S@PPy nanoparticles,forming a three-dimensional conductive network. When evaluating the electrochemical performance of S@PPy/GS in a lithium–sulfur battery,it delivers large discharge capacity,excellent cycle stability,and good rate capability. The initial discharge capacity is up to 1040 m Ah/g at 0.1 C,the capacity can remain 537.8 m Ah/g at 0.2 C after 200 cycles,even at a higher rate of 1 C,the specific capacity still reaches 566.5 m Ah/g. The good electrochemical performance is attributed to the unique structure of S@PPy/GS,which can not only provide an excellent transport of lithium and electron ions within the electrodes,but also retard the shuttle effect of soluble lithium polysulfides effectively,thus plays a positive role in building better lithium-sulfur batteries.
基金supported by the financial aid from National Science and Technology Major Project of China(No.2022YFB3504000)National Natural Science Foundation of China(Nos.22020102003,22025506 and 22271274)。
文摘Bare Pd metal nanoparticles invariably suffer from poor selectivity in furfural hydrogenation by forming flat configurations,with the aromatic ring of the substrate molecules parallel to the metal surface.Herein,we put forward a promising solution by using CeO_(2)as promoters to modify Pd nanoparticles for modulating the adsorption behaviors of furfural molecules.To achieve the highly-desired ultra-small Pd@CeO_(2)core@shell nanostructure,a“constrained auto-redox”synthesis is developed,in which silicalite-1 supports play the key role of providing their surface as the landing place of PdO_(x)precursors for inhibiting the overgrowth and the deformation.To the best of our knowledge,this is one of the smallest core@shell materials obtained from aqueous synthesis.When evaluated as catalysts,Pd@CeO_(2)/S-1 gives 98.9%conversion of furfural with 94.3%selectivity for furfural alcohol in 15 h,which is much better than that of Pd/S-1(88.6%conversion with 44.3%selectively).The DFT simulation reveals a strong interaction between the defects of CeO_(2)and the oxygen atom of the–CHO group in furfural molecules,which benefits the selective hydrogenation occurred in the–CHO group rather than the furan ring.
基金financially supported by the Doctorial Start-up Fund of Guizhou University(2011–05)Fok Ying Tung Education Foundation(171095)+1 种基金Talent Project of Guizhou Provincial Education Department(2022–094)National Natural Science Foundation of China(No.11964006).
文摘It is well recognized that interfacial effect and/or impedance matching play a great impact on microwave absorption.Herein,we proposed a facile strategy to take full advantage of interface engineering and impedance matching for boosting microwave absorption performance(MAPs).Three-dimensional(3D)hierarchical urchin-like core@shell structured NiO/Ni@CNTs multicomponent nanocomposites(MCNCs)were elaborately constructed and produced in high efficiency through a facile continuous chemical bath deposition,thermal treatment,and catalytic chemical vapor decomposition process.By controlling the pyrolysis time,the NiO/Ni@CNTs urchin-like MCNCs with different lengths and aggregation degrees of CNTs could be selectively synthesized.The obtained results revealed that the enhanced CNT contents provided abundant interfaces and effectively aggrandized their interfacial effects,which resulted in improved polarization loss,conductivity loss,and comprehensive MAPs.Impressively,the interfaces and impedance matching in the designed NiO/Ni@CNTs urchin-like MCNCs could be optimized by regulating the pyrolysis temperature,which further improved the comprehensive MAPs.And the designed NiO/Ni@CNTs urchin-like MCNCs could simultaneously display strong absorption capabilities,broad absorption bandwidths,and thin matching thicknesses.Therefore,our findings not only provided a simple and universal approach to produce core@shell structured magnetic carbon-based urchin-like MCNCs but also presented an interface engineering and impedance matching strategy to develop the tunable,strong absorption,broadband,lightweight high-efficiency microwave absorbers.
基金This work was supported by the Fund of Fok Ying Tung Edu-cation Foundation,the Major Research Project of Innovative Group of Guizhou province(No.2018-013)Open Fund from Henan Uni-versity of Science and Technology,the National Science Foundation of China(Nos.11964006 and 11774156)the Foundation of the National Key Project for Basic Research(No.2012CB932304)for fi-nancial support。
文摘Previous results revealed that the defect and/or interface had a great impact on the electromagnetic pa-rameters of materials.In order to understand the main physical mechanisms and effectively utilize these strategies,in this study,M Fe_(2)O_(4)and flower-like core@shell M Fe_(2)O_(4)@MoS_(2)(M=Mn,Ni,and Zn)sam-ples with different categories were elaborately designed and selectively produced in large scale through a simple two-step hydrothermal reaction.We conducted the systematical investigation on their microstruc-tures,electromagnetic parameters and microwave absorption performances(MAPs).The obtained results revealed that the large radius of M^(2+)cation could effectively boost the concentration of oxygen vacancy in the M Fe_(2)O_(4)and M Fe_(2)O_(4)@MoS_(2)samples,which resulted in the improvement of dielectric loss capabil-ities and MAPs.Furthermore,the introduction of MoS_(2)nanosheets greatly improved the interfacial effect and enhanced the polarization loss capabilities,which also boosted the MAPs.By taking full advantage of the defect and interface,the designed M Fe_(2)O_(4)@MoS_(2)samples displayed tunable and excellent com-prehensive MAPs including strong absorption capability,wide absorption bandwidth and thin matching thicknesses.Therefore,the clear understanding of defect and interface engineering made these strategies well elaborately designed and applicable to improving MAPs.
基金financially supported by the Doctorial Start-up Fund of Guizhou University(No.2011-05)the Fund of Fok Ying Tung Education Foundation,the Major Research Project of innovative Group of Guizhou province(No.2018-013)+1 种基金the Guizhou Provincial Science and Technology Projects(No.ZK 2022-General 044)the National Science Foundation of China(Nos.11604060 and 11964006).
文摘Due to the good manipulation of electronic structure and defect,anion regulating should be a promising strategy to regulate the electromagnetic(EM)parameters and optimize the EM wave absorption performances(EMWAPs).In this work,we proposed a facile route for the large-scale production of core@shell structured hollow carbon spheres@MoSxSe_(2−x)(x=0.2,0.6,and 1.0)multicomponent nanocomposites(MCNCs)through a mild template method followed by hydrothermal process.The obtained results revealed that the designed hollow carbon spheres@MoSxSe_(2−x)MCNCs presented the improved sulfur vacancy concentration by regulating the x value from 0.2 to 1.0.The obtained hollow carbon spheres@MoSxSe_(2−x)MCNCs displayed the extraordinary comprehensive EMWAPs because of the introduced abundant defects and excellent interfacial effects.Furthermore,the as-prepared hollow carbon spheres@MoSxSe_(2−x)MCNCs presented the progressively improved comprehensive EMWAPs with the x value increasing from 0.2 to 1.0,which could be explained by their boosted polarization loss abilities and impedance matching characteristics originating from the enhanced sulfur vacancy concentration.Therefore,our findings not only demonstrated that the anion regulating was a promising method to optimize EM parameters and EMWAPs,but also provided a facile route to design the transition metal dichalcogenides-based MCNCs as the much more attractive candidates for highperformance microwave absorbers.
基金supported by the National Key R&D Program of China(2016YFA0204100 and 2017YFA0208200)the National Natural Science Foundation of China(21571135)+5 种基金Young Thousand Talented ProgramNatural Science Foundation of Jiangsu Higher Education Institutions(17KJB150032)the Project of Scientific and Technologic Infrastructure of Suzhou(SZS201708)the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)Postgraduate Research&Practice Innovation Program of Jiangsu Province(KYCX19_1896)the Start-Up Supports from Soochow University.
文摘The design of electrocatalysts with enhanced adsorption and activation of nitrogen(N2)is critical for boosting the electrochemical N2reduction(ENR).Herein,we developed an efficient strategy to facilitate N2 adsorption and activation for N2 electroreduction into ammonia(NH3)by vacancy engineering of core@shell structured Au@Sn O2 nanoparticles(NPs).We found that the ultrathin amorphous SnO2 shell with enriched oxygen vacancies was conducive to adsorb N2as well as promoted the N2 activation,meanwhile the metallic Au core ensured the good electrical conductivity for accelerating electrons transport during the electrochemical N2 reduction reaction,synergistically boosting the N2 electroreduction catalysis.As confirmed by the15N-labeling and controlled experiments,the core@shell Au@amorphous SnO2 NPs with abundant oxygen vacancies show the best performance for N2 electroreduction with the NH3 yield rate of 21.9 lg h-1mg-1catand faradaic efficiency of 15.2%at-10.2 VRHE,which surpass the Au@crystalline SnO2 NPs,individual Au NPs and all reported Au-based catalysts for ENR.
基金National Natural Science Foundation of China (Nos. 21590794, 21771173, and 21521092)project development plan of science and technology of Jilin Province (Nos. 20180101179JC and 20160520126JH)CAS-CSIRO project (GJHZ1730).
文摘The Pt-Ni nanoframe catalysts have attracted great interest owing to their unique electronic structure and excellent catalytic performance. However, the stability of the tenu ous edges of nano frame-structures is dissatisfactory and their un iversal applicati ons in catalytic market beyond electrocatalytic reactions are yet to be tapped and explored. Herein, we developed a new core@ shell structured Pt-Ni nanoframe@CeO2 (Pt-Ni NF@CeO2) composite via etching the Ni from inhomogeneous Pt-Ni rhombic dodecahedra (Pt-Ni RD) by cerium(lll) acetate hydrate (Ce(OAc)3). In this path, Pt-Ni RD was used as self-sacrificial 怕mplate, while the Ce(OAc)3 serves as the provider of the Ce3* source and OH' for the formation of CeO2 shell, etchant of Pt-Ni RD, and the surface modification agent. By this way, the etching of Pt-Ni RD and the formation of the CeO2 shell are simultaneously proceeded to form the final Pt-Ni NF@CeO2 in one step. The obtained Pt-Ni NF@CeO2 exhibits strong in terfacial charge tran sfer interactio n betwee n Pt-Ni NF core and CeO2 shell eve n without reductio n treatment, leading to enhan ced catalytic activity in the hydrogenation of phenylacetylene. After introduction of trace silver, the Pt-Ni-Ag4.9 NF@CeO2 achieves remarkable catalytic performa nee for the selective con versi on of phe ny lacetyle ne to styrene: high con version (100%), styre ne selectivity (86.5%), and good stability. It reveals that enc apsulatio n n oble metal nano frames into metal oxide to form core @ shell structured hybrids will in deed enhance their stability and catalytic properties. Particularly, this work expends the application of noble metal nanoframes materials to hydrogenation reacti ons.
基金the Fund of Fok Ying Tung Education Foundation,the Natural Science Foundation of Guizhou province(No.2017-1034)the Major Research Project of innovative Group of Guizhou province(No.2018-013)+1 种基金the Natural National Science Foundation of China(Nos.11604060,52101010,and 11964006)the Foundation of the National Key Project for Basic Research(No.2012CB932304)for financial support.
文摘Defect and interface engineering are efficient approaches to adjust the physical and chemical properties of nanomaterials.In order to effectively utilize these strategies for the improvement of microwave absorption properties(MAPs),in this study,we reported the synthesis of hollow carbon shells and hollow carbon@MoS_(2)nanocomposites by the template-etching and templateetching-hydrothermal methods,respectively.The obtained results indicated that the degree of defect for hollow carbon shells and hollow carbon@MoS_(2)could be modulated by the thickness of hollow carbon shell,which effectively fulfilled the optimization of electromagnetic parameters and improvement of MAPs.Furthermore,the microstructure investigations revealed that the precursor of hollow carbon shells was encapsulated by the sheet-like MoS_(2)in high efficiency.And the introduction of MoS_(2)nanosheets acting as the shell effectively improved the interfacial effects and boosted the polarization loss capabilities,which resulted in the improvement of comprehensive MAPs.The elaborately designed hollow carbon@MoS_(2)samples displayed very outstanding MAPs including strong absorption capabilities,broad absorption bandwidth,and thin matching thicknesses.Therefore,this work provided a viable strategy to improve the MAPs of microwave absorbers by taking full advantage of their defect and interface engineering.
基金financially supported by the Fund of Fok Ying Tung Education Foundationthe Major Research Project of innovative Group of Guizhou province(2018–013)+2 种基金the Open Fund from Henan University of Science and Technologythe National Science Foundation of China(Nos.11964006 and 11774156)the Foundation of the National Key Project for Basic Research(No.2012CB932304)。
文摘In this work,we put forward a scheme to exquisitely design and selectively synthesize the core@shell structured MSe_(2)/FeSe_(2)@MoSe_(2)(M=Co,Ni)flower-like multicomponent nanocomposites(MCNCs)through a simple two-step hydrothermal reaction on the surfaces of MFe_(2)O_4 nanospheres with the certain amounts of Mo and Se sources.With increasing the amounts of Mo and Se sources,the obtained core@shell structured MSe_(2)/FeSe_(2)@MoSe_(2)(M=Co,Ni)MCNCs with the enhanced content of MoSe_(2)and improved flower-like geometry morphology could be produced on a large scale.The obtained results revealed that the as-prepared samples displayed improved comprehensive microwave absorption properties(CMAPs)with the increased amounts of Mo and Se sources.The as-prepared CoSe_(2)/FeSe_(2)@MoSe_(2)and NiSe_(2)/FeSe_(2)@MoSe_(2)MCNCs with the well-defined flower-like morphology could simultaneously present the outstanding CMAPs in terms of strong absorption capability,wide absorption bandwidth,and thin matching thicknesses,which mainly originated from the conduction loss and flower-like geometry morphology.Therefore,the findings not only develop the very desirable candidates for high-performance microwave absorption materials but also pave a new way for optimizing the CMAPs through tailoring morphology engineering.
基金This work was supported by the financial aid from the National Natural Science Foundation of China (Nos. 91122030, 51272249, 21210001, 21221061 and 21401186), and the National Key Basic Research Program of China (No. 2014CB643802).
文摘In this study, Co3O4@CeO2 core@shell nanowires were successfully prepared via thermal decomposition of Co(CO3)0.5(OH).0.11H2O@CeO2 core@shell nanowire precursors. As a CO oxidation catalyst, Co3O4@CeO2 shows remarkably enhanced catalytic performance compared to Co3O4 nanowires and CeO2 nanoparticles (NPs), indicating obvious synergistic effects between the two components. It also suggests that the CeO2 shell coating can effectively prevent Co3O4 nanowires from agglomerating, hence effecting a substantial improvement in the structural stability of the Co3O4 catalyst. Furthermore, the fabrication of the welbdisperse4 core@shell structure results in a maximized interface area between Co3O4 and CeO2, as well as a reduced Co3O4 size, which may be responsible for the enhanced catalytic activity of Co3O4@CeO2. Further examination revealed that CO oxidation may occur at the interface of Co3O4 and CeO2. The influence of calcination temperatures and the component ratio between Co3O4 and CeO2 were then investigated in detail to determine the catalytic performance of Co3O4@CeO2 core@shell nanowires, the best of which was obtained by calcination at 250 ℃ for 3 h with a Ce molar concentration of about 38.5%. This sample achieved 100% CO conversion at a reduced temperature of 160 ℃. More importantly, more than 2.5 g of the Co3O4@CeO2 core@shell nanowires were produced in one pot by this simple process, which may be beneficial for practical applications as automobile-exhaust gas-treatment catalysts.
基金The authors thank the National Natural Science Foundation of China(Nos.U1804140,U20041100 and 21801015)for supportThis work is also supported by Beijing Institute of Technology Research Fund Program for Young Scholars(No.3090012221909).
文摘Rational design and construction of low-cost and highly efficient electrocatalysts for hydrogen evolution reaction(HER)is meaningful but challenging.Herein,a robust three dimensional(3D)hollow CoSe_(2)@ultrathin MoSe_(2)core@shell heterostructure(CoSe_(2)@MoSe_(2))is proposed as an efficient HER electrocatalyst through interfacial engineering.Benefitting from the abundant heterogeneous interfaces on CoSe_(2)@MoSe_(2),the exposed edge active sites are maximized and the charge transfer at the hetero-interfaces is accelerated,thus facilitating the HER kinetics.It exhibits remarkable performance in pH-universal conditions.Notably,it only needs an overpotential(η10)of 108 mV to reach a current density of 10 mA·cm^(-2)in 1.0 M KOH,outperforming most of the reported transition metal selenides electrocatalysts.Density functional theory(DFT)calculations unveil that the heterointerfaces synergistically optimize the Gibbs free energies of H2O and H^(*)during alkaline HER,accelerating the reaction kinetics.The present work may provide new construction guidance for rational design of high-efficient electrocatalysts.
基金We gratefully acknowledge the financial support from the K.C.Wong Education Foundation of Hong Kong,the National Natural Science Foundation of China(No.20571068)the Program for New Century Excellent Talents at Universities from the Chinese Ministry of Education(No.NCET2006-0552)+2 种基金the Foundation of Anhui Provincial Education Department(No.KJ2008A071)the Creative Research Foundation for Graduates of USTC(No.KD2008019)the Chinese Academy of Sciences(CAS)Special Grant for Postgraduate Research,Innovation and Practice(2008).
文摘We report the synthesis of one-dimensional(1-D)magnetic Fe_(2)P nanowires and Fe_(2)P@C core@shell nanocables by the reactions of triphenylphosphine(PPh_(3))with Fe powder(particles)and ferrocene(Fe(C_(5)H_(5))_(2)),respectively,in vacuum-sealed ampoules at 380-400℃.The synthesis is based on chemical conversion of micrometer or nanometer sized Fe particles into Fe_(2)P via the extraction of phosphorus from liquid PPh_(3) at elevated temperatures.In order to control product diameters,a convenient sudden-temperature-rise strategy is employed,by means of which diameter-uniform Fe_(2)P@C nanocables are prepared from the molecular precursor Fe(C_(5)H_(5))2.In contrast,this strategy gives no obvious control over the diameters of the Fe_(2)P nanowires obtained using elemental Fe as iron precursor.The formation of 1-D Fe_(2)P nanostructures is ascribed to the cooperative effects of the kinetically induced anisotropic growth and the intrinsically anisotropic nature of hexagonal Fe_(2)P crystals.The resulting Fe_(2)P nanowires and Fe_(2)P@C nanocables display interesting ferromagnetic-paramagnetic transition behaviors with blocking temperatures of 230 and 268 K,respectively,significantly higher than the ferromagnetic transition temperature of bulk Fe_(2)P(TC=217 K).
文摘化工、纺织印染与农药化肥等产业的蓬勃发展推动着人类社会的进步,但同时也给环境治理带来了巨大难题。目前,光催化降解局限于在特定波长下针对单一有机污染物进行降解,然而现实中的情况往往更复杂。因此,开发一种多功能光催化材料用于光催化降解不同有机污染物显得尤为重要。采用一步无模板溶剂热法合成了核壳结构的C-TiO_(2)复合材料前驱体,并在氩气气氛下煅烧得到高结晶度的C-TiO_(2)复合光催化材料。运用SEM、TEM、XRD和TG等表征手段对材料进行表征,结论如下:550℃煅烧时的样品为包含少量碳的高结晶度的锐钛矿相TiO 2,且550℃煅烧时的样品依然保持了完整的核壳结构。此外,C-TiO_(2)复合材料的比表面积高达85.69 m 2·g^(-1),平均孔径为16.4 nm以及孔体积为0.423 m 3·g^(-1)。在UV-Vis光照射下,C-TiO_(2)复合材料分别对罗丹明B(RhB)、亚甲基蓝(MB)和刚果红(CR)3种染料显示出增强的光催化降解活性。