Two-dimensional layered IV-VI chalcogenides are attracting great interest for applications in next-generation optoelectronic, photovoltaic, and thermoelectric devices. However, great challenges in the controllable syn...Two-dimensional layered IV-VI chalcogenides are attracting great interest for applications in next-generation optoelectronic, photovoltaic, and thermoelectric devices. However, great challenges in the controllable synthesis of high-quality IV-VI chalcogenide nanostructures have hindered their in-depth studies and practical applications to date. Here we report, for the first time, a feasible synthesis of single-crystal IV-VI SnSe nanoplates in a controlled manner on mica substrates by vapor transport deposition. The as-grown SnSe nanoplates have approximately square shapes with controllable side lengths varying from I to 6 Dm. Electrical transport and optoelectronic measurements show that as-obtained SnSe nanoplates display p-type conductivity and high photoresponsivity.展开更多
Two-dimensional(2D)metal-organic frameworks(MOFs)are promising for electrocatalysis with high performance,as they possess large surface areas and high densities of exposed active sites.It attracts tremendous attention...Two-dimensional(2D)metal-organic frameworks(MOFs)are promising for electrocatalysis with high performance,as they possess large surface areas and high densities of exposed active sites.It attracts tremendous attention to obtain 2D nanostructures via simple preparation methods.Herein,a facile pyridine-modulated solvothermal synthesis of Ni/Co bimetallic MOF nanoplates(NixCoy-bpy(PyM))is reported with well-defined 2D morphology with a thickness as thin as 20 nm and an aspect ratio larger than 50.These nanoplates possess oxygen evolution reaction activity as electrocatalysts in alkaline conditions.Specifically,Ni0.5Co1.5-bpy(PyM)exhibits excellent OER electrocatalytic activity with a low overpotential of 256 mV at 10 m A cm-2 and a small Tafel slope of 81.8 mV dec-1 in 1.0 mol L-1 KOH with long-term electrochemical stability for 3000 cyclic voltammetry cycles.The high catalytic activity of Ni0.5Co1.5-bpy(PyM)can be attributed to the in situ formed active hydroxide and oxyhydroxide species within the inherited 2D morphology and the optimized bimetallic ratio.展开更多
Highly porous materials have attracted intensive attention in the past decades due to their unique geometrical configuration, unusual structural features, and outstanding physicochemical properties, but the facile cre...Highly porous materials have attracted intensive attention in the past decades due to their unique geometrical configuration, unusual structural features, and outstanding physicochemical properties, but the facile creation of porous metal nanomaterias remains a formidable challenge. Most reports focused on using hard templates to create porous metal nanomaterials via sacrificing the templates. Herein, we have created a new class of porous PtPb/Pt nanocrystals(NCs)with well-defined morphology, composition and porosity through a facile chemical etching approach. Due to the highly open three-dimensional(3D) structure and alloy effect, the porous PtPb/Pt NCs exhibit enhanced performances towards polyhydric alcohol electrooxidations with the optimized porous Pt3Pb nanoplates exhibiting superior activities of 1.75 mA cm-2 and 1.19 A mgPt-1 for ethylene glycol oxidation reaction(EGOR) and of 1.46 m A cm-2 and 1.00 A mg-1Pt for glycerol oxidation reaction(GOR) that are much higher than the commercial Pt/C(0.34 mA cm-2 and 0.22 A mgPt-1 for EGOR, 0.30 mA cm-2 and 0.20 A mgPt-1for GOR). In addition, the porous Pt3Pb nanoplates can endure the long-term stability in EG and glycerol oxidation reactions with limited activity and structure change after 20,000 and 5,000 cycles,respectively, showing a highly promising class of porous Ptbased electrocatalysts for direct polyhydric alcohol fuel cells and beyond.展开更多
In this paper,we analytically study vibration of functionally graded piezoelectric(FGP)nanoplates based on the nonlocal strain gradient theory.The top and bottom surfaces of the nanoplate are made of PZT-5H and PZT-4,...In this paper,we analytically study vibration of functionally graded piezoelectric(FGP)nanoplates based on the nonlocal strain gradient theory.The top and bottom surfaces of the nanoplate are made of PZT-5H and PZT-4,respectively.We employ Hamilton’s principle and derive the governing differential equations.Then,we use Navier’s solution to obtain the natural frequencies of the FGP nanoplate.In the first step,we compare our results with the obtained results for the piezoelectric nanoplates in the previous studies.In the second step,we neglect the piezoelectric effect and compare our results with those obtained for the functionally graded(FG)nanoplates.Finally,the effects of the FG power index,the nonlocal parameter,the aspect ratio,and the lengthto-thickness ratio,and the nanoplate shape on natural frequencies are investigated.展开更多
SrMoO4 nanoplates were synthesized by a facile reverse microemulsion method at room temperature.Energy evolution of this in situ growth process was monitored by means of a microcalorimeter.A sharp exothermic peak for ...SrMoO4 nanoplates were synthesized by a facile reverse microemulsion method at room temperature.Energy evolution of this in situ growth process was monitored by means of a microcalorimeter.A sharp exothermic peak for the initial reaction and two discontinuous relatively weak exothermic peaks for the subsequent crystal growth emerged on the microcalorimetric heat flow curve.Based on the in situ thermokinetic data,the rate constants of the nucleation process and crystallization process at 298.15 K were calculated to be 4.078×10-3 and 5.033×10-4 s-1,respectively.The growth mechanism and energy evolution were investigated.展开更多
Herein, hierarchically structured SnO2 microspheres are designed and synthesized as an efficient anode material for lithium-ion batteries using hollow SnO2 nanoplates. Three-dimensionally ordered macroporous （3-DOM）...Herein, hierarchically structured SnO2 microspheres are designed and synthesized as an efficient anode material for lithium-ion batteries using hollow SnO2 nanoplates. Three-dimensionally ordered macroporous （3-DOM） SnOx-C microspheres synthesized by spray pyrolysis are transformed into hierarchically structured SnO2 microspheres by a two-step post-treatment process. Sulfidation produces hierarchically structured SnS-SnS2-C microspheres comprising tin sulfide nanoplate and carbon building blocks. A subsequent oxidation process produces SnO2 microspheres from hollow SnO2 nanoplate building blocks, which are formed by Kirkendall diffusion. The discharge capacity of the hierarchically structured SnO2 microspheres at a current density of 5 Ag^-1 for the 600th cycle is 404 mA·h·g^-1. The hierarchically structured SnO2 microspheres have reversible discharge capacities of 609 and 158 mA·h·g^-1 at current densities of 0.5 and 30 Ag^-1, respectively. The ultrafine nanosheets contain empty voids that allow excellent lithium-ion storage performance, even at high current densities.展开更多
Organic-inorganic hybrid perovskites attract considerable attention owing to their applications in high-efficiency solar cells and light emission. Compared with three-dimensional perovskites, two-dimensional （2D） la...Organic-inorganic hybrid perovskites attract considerable attention owing to their applications in high-efficiency solar cells and light emission. Compared with three-dimensional perovskites, two-dimensional （2D） layered hybrid perovskites have a higher exciton binding energy and potentially higher light- emission efficiency. The growth of high-quality crystalline 2D perovskites with a well-defined nanoscale morphology is desirable because they can be suitable building blocks for integrated optoelectronics and （nano）photonics. Herein, we report the facile solution growth of single-crystal microplates of 2D perovskites based on a 2-phenylethylammonium （C6HsCH2CH2NHG PEA） cation, （PEA）2PbX- （X = Br, I）, with a well-defined rectangular geometry and nanoscale thickness through a dissolution-recrystallization process. The crystal structures of （PEA）2PbX4 are first confirmed using single-crystal X-ray diffraction. A solution-phase transport-growth process is developed to grow microplates with a typical size of tens of micrometers and thickness of hundreds of nanometers on another clean substrate different from the substrate coated with lead-acetate precursor film. Surface-topography analysis suggests that the formation of the 2D microplates is likely driven by the wedding-cake growth mechanism. Through halide alloying, the photoluminescence emission of （PEA）2Pb（Br, I）4 perovskites with a narrow peak bandwidth is readily tuned from violet （-410 nm） to green （-530 nm）.展开更多
This study investigates the size-dependent wave propagation behaviors under the thermoelectric loads of porous functionally graded piezoelectric(FGP) nanoplates deposited in a viscoelastic foundation.It is assumed tha...This study investigates the size-dependent wave propagation behaviors under the thermoelectric loads of porous functionally graded piezoelectric(FGP) nanoplates deposited in a viscoelastic foundation.It is assumed that(i) the material parameters of the nanoplates obey a power-law variation in thickness and(ii) the uniform porosity exists in the nanoplates.The combined effects of viscoelasticity and shear deformation are considered by using the Kelvin-Voigt viscoelastic model and the refined higher-order shear deformation theory.The scale effects of the nanoplates are captured by employing nonlocal strain gradient theory(NSGT).The motion equations are calculated in accordance with Hamilton’s principle.Finally,the dispersion characteristics of the nanoplates are numerically determined by using a harmonic solution.The results indicate that the nonlocal parameters(NLPs) and length scale parameters(LSPs) have exactly the opposite effects on the wave frequency.In addition,it is found that the effect of porosity volume fractions(PVFs) on the wave frequency depends on the gradient indices and damping coefficients.When these two values are small,the wave frequency increases with the volume fraction.By contrast,at larger gradient index and damping coefficient values,the wave frequency decreases as the volume fraction increases.展开更多
In this work,a series of BiOBr nanoplates with oxygen vacancies(OVs)were synthesized by a solvothermal method using a water/ethylene glycol solution.The number of OVs and facets of BiOBr were tuned by changing the wat...In this work,a series of BiOBr nanoplates with oxygen vacancies(OVs)were synthesized by a solvothermal method using a water/ethylene glycol solution.The number of OVs and facets of BiOBr were tuned by changing the water/ethylene glycol ratio.Although the role of OVs in photocatalysis has been investigated,the underlying mechanisms of charge transfer and reactant activation remain unknown.To unravel the effect of OVs on the reactant activation and photocatalytic NO oxidation process,in situ diffuse reflectance infrared Fourier transform spectroscopy,so‐called DRIFTS,and theoretical calculations were performed and their results combined.The photocatalytic efficiency of the as‐prepared BiOBr was significantly increased by increasing the amount of OVs.The oxygen vacancies had several effects on the photocatalysts,including the introduction of intermediate energy levels that enhanced light absorption,promoted electron transfer,acted as active sites for catalytic reaction and the activation of oxygen molecules,and facilitated the conversion of the intermediate products to the final product,thus increasing the overall visible light photocatalysis efficiency.The present work provides new insights into the understanding of the role of OVs in photocatalysts and the mechanism of photocatalytic NO oxidation.展开更多
Lyotropic liquid crystals(LLCs)produced by the self-assembly of surfactant in water represent an important class of highly ordered soft materials that have a wide range of applications.This study investigates the LLCs...Lyotropic liquid crystals(LLCs)produced by the self-assembly of surfactant in water represent an important class of highly ordered soft materials that have a wide range of applications.This study investigates the LLCs formed by a zwitterionic surfactant(tetradecyldimethylaminoxide,C 14 DMAO)in water.The organization of C 14 DMAO within the LLCs was determined based on a detailed analysis of small-angle X-ray scattering measure-ments and polarized microscopy observations of a typical sample.Additional to the singe-phase region,which has a hexagonal organization,several two-phase regions were observed,exhibiting the coexistence of hexago-nal/cubic,cubic/lamellar,and hexagonal/lamellar phases.The phase behavior showed an obvious dependence on temperature,with more pronounced two-phase regions at lower temperatures.Using the LLCs as a matrix,Au nanospheres,nanoellipsoids,and nanorods were prepared without requiring additional reducing reagents.These three-and one-dimensional Au nanomaterials could be converted to two-dimensional plates via the introduc-tion of a small amount of cationic surfactant to the LLCs,such as cetyltrimethylammonium bromide(CTAB)and 1-hexadecyl-3-methylimidazolium bromide([C 16 MIm]B),which showed pronounced surface-enhanced Raman scattering activity towards solid rhodamine.The LLCs loaded with CTAB(or[C 16 MIm]B)and HAuCl 4 exhibited slightly different structures and mechanical strength from the original LLCs,thereby forming a new class of highly crowded colloidal materials.展开更多
基金supported by the Key Laboratory of Preparation and Application of Environmentally Friendly Materials of the Ministry of Educationof ChinaDoctoral Scientific Research Project of Jilin Normal University,China~~
文摘Two-dimensional layered IV-VI chalcogenides are attracting great interest for applications in next-generation optoelectronic, photovoltaic, and thermoelectric devices. However, great challenges in the controllable synthesis of high-quality IV-VI chalcogenide nanostructures have hindered their in-depth studies and practical applications to date. Here we report, for the first time, a feasible synthesis of single-crystal IV-VI SnSe nanoplates in a controlled manner on mica substrates by vapor transport deposition. The as-grown SnSe nanoplates have approximately square shapes with controllable side lengths varying from I to 6 Dm. Electrical transport and optoelectronic measurements show that as-obtained SnSe nanoplates display p-type conductivity and high photoresponsivity.
基金supported by the National Natural Science Foundation of China(U1904215,21671170 and 21875207)the Top-notch Academic Programs Project of Jiangsu Higher Education Institutions(TAPP)+4 种基金the Program for New Century Excellent Talents of the University in China(NCET-13-0645)the Six Talent Plan(2015XCL-030)Qinglan Projectthe Priority Academic Program Development of Jiangsu Higher Education Institutionsthe support from the postdoctoral fund of Yangzhou University。
文摘Two-dimensional(2D)metal-organic frameworks(MOFs)are promising for electrocatalysis with high performance,as they possess large surface areas and high densities of exposed active sites.It attracts tremendous attention to obtain 2D nanostructures via simple preparation methods.Herein,a facile pyridine-modulated solvothermal synthesis of Ni/Co bimetallic MOF nanoplates(NixCoy-bpy(PyM))is reported with well-defined 2D morphology with a thickness as thin as 20 nm and an aspect ratio larger than 50.These nanoplates possess oxygen evolution reaction activity as electrocatalysts in alkaline conditions.Specifically,Ni0.5Co1.5-bpy(PyM)exhibits excellent OER electrocatalytic activity with a low overpotential of 256 mV at 10 m A cm-2 and a small Tafel slope of 81.8 mV dec-1 in 1.0 mol L-1 KOH with long-term electrochemical stability for 3000 cyclic voltammetry cycles.The high catalytic activity of Ni0.5Co1.5-bpy(PyM)can be attributed to the in situ formed active hydroxide and oxyhydroxide species within the inherited 2D morphology and the optimized bimetallic ratio.
基金financially supported by the Ministry of Science and Technology (2016YFA0204100,2017YFA0208200)the National Natural Science Foundation of China (21571135)+4 种基金the Young Thousand Talented Programthe Natural Science Foundation of Jiangsu Higher Education Institutions (17KJB150032)the project of scientific and technologic infrastructure of Suzhou (SZS201708)start-up support from Soochow Universitythe Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD)
文摘Highly porous materials have attracted intensive attention in the past decades due to their unique geometrical configuration, unusual structural features, and outstanding physicochemical properties, but the facile creation of porous metal nanomaterias remains a formidable challenge. Most reports focused on using hard templates to create porous metal nanomaterials via sacrificing the templates. Herein, we have created a new class of porous PtPb/Pt nanocrystals(NCs)with well-defined morphology, composition and porosity through a facile chemical etching approach. Due to the highly open three-dimensional(3D) structure and alloy effect, the porous PtPb/Pt NCs exhibit enhanced performances towards polyhydric alcohol electrooxidations with the optimized porous Pt3Pb nanoplates exhibiting superior activities of 1.75 mA cm-2 and 1.19 A mgPt-1 for ethylene glycol oxidation reaction(EGOR) and of 1.46 m A cm-2 and 1.00 A mg-1Pt for glycerol oxidation reaction(GOR) that are much higher than the commercial Pt/C(0.34 mA cm-2 and 0.22 A mgPt-1 for EGOR, 0.30 mA cm-2 and 0.20 A mgPt-1for GOR). In addition, the porous Pt3Pb nanoplates can endure the long-term stability in EG and glycerol oxidation reactions with limited activity and structure change after 20,000 and 5,000 cycles,respectively, showing a highly promising class of porous Ptbased electrocatalysts for direct polyhydric alcohol fuel cells and beyond.
文摘In this paper,we analytically study vibration of functionally graded piezoelectric(FGP)nanoplates based on the nonlocal strain gradient theory.The top and bottom surfaces of the nanoplate are made of PZT-5H and PZT-4,respectively.We employ Hamilton’s principle and derive the governing differential equations.Then,we use Navier’s solution to obtain the natural frequencies of the FGP nanoplate.In the first step,we compare our results with the obtained results for the piezoelectric nanoplates in the previous studies.In the second step,we neglect the piezoelectric effect and compare our results with those obtained for the functionally graded(FG)nanoplates.Finally,the effects of the FG power index,the nonlocal parameter,the aspect ratio,and the lengthto-thickness ratio,and the nanoplate shape on natural frequencies are investigated.
基金Supported by the National Natural Science Foundation of China(No.20963001)the Major Project of Natural Science Foundation of Guangxi Province,China(No.0991001Z)
文摘SrMoO4 nanoplates were synthesized by a facile reverse microemulsion method at room temperature.Energy evolution of this in situ growth process was monitored by means of a microcalorimeter.A sharp exothermic peak for the initial reaction and two discontinuous relatively weak exothermic peaks for the subsequent crystal growth emerged on the microcalorimetric heat flow curve.Based on the in situ thermokinetic data,the rate constants of the nucleation process and crystallization process at 298.15 K were calculated to be 4.078×10-3 and 5.033×10-4 s-1,respectively.The growth mechanism and energy evolution were investigated.
文摘Herein, hierarchically structured SnO2 microspheres are designed and synthesized as an efficient anode material for lithium-ion batteries using hollow SnO2 nanoplates. Three-dimensionally ordered macroporous （3-DOM） SnOx-C microspheres synthesized by spray pyrolysis are transformed into hierarchically structured SnO2 microspheres by a two-step post-treatment process. Sulfidation produces hierarchically structured SnS-SnS2-C microspheres comprising tin sulfide nanoplate and carbon building blocks. A subsequent oxidation process produces SnO2 microspheres from hollow SnO2 nanoplate building blocks, which are formed by Kirkendall diffusion. The discharge capacity of the hierarchically structured SnO2 microspheres at a current density of 5 Ag^-1 for the 600th cycle is 404 mA·h·g^-1. The hierarchically structured SnO2 microspheres have reversible discharge capacities of 609 and 158 mA·h·g^-1 at current densities of 0.5 and 30 Ag^-1, respectively. The ultrafine nanosheets contain empty voids that allow excellent lithium-ion storage performance, even at high current densities.
文摘Organic-inorganic hybrid perovskites attract considerable attention owing to their applications in high-efficiency solar cells and light emission. Compared with three-dimensional perovskites, two-dimensional （2D） layered hybrid perovskites have a higher exciton binding energy and potentially higher light- emission efficiency. The growth of high-quality crystalline 2D perovskites with a well-defined nanoscale morphology is desirable because they can be suitable building blocks for integrated optoelectronics and （nano）photonics. Herein, we report the facile solution growth of single-crystal microplates of 2D perovskites based on a 2-phenylethylammonium （C6HsCH2CH2NHG PEA） cation, （PEA）2PbX- （X = Br, I）, with a well-defined rectangular geometry and nanoscale thickness through a dissolution-recrystallization process. The crystal structures of （PEA）2PbX4 are first confirmed using single-crystal X-ray diffraction. A solution-phase transport-growth process is developed to grow microplates with a typical size of tens of micrometers and thickness of hundreds of nanometers on another clean substrate different from the substrate coated with lead-acetate precursor film. Surface-topography analysis suggests that the formation of the 2D microplates is likely driven by the wedding-cake growth mechanism. Through halide alloying, the photoluminescence emission of （PEA）2Pb（Br, I）4 perovskites with a narrow peak bandwidth is readily tuned from violet （-410 nm） to green （-530 nm）.
基金Project supported by the National Natural Science Foundation of China(Nos.11502218 and 11672252)。
文摘This study investigates the size-dependent wave propagation behaviors under the thermoelectric loads of porous functionally graded piezoelectric(FGP) nanoplates deposited in a viscoelastic foundation.It is assumed that(i) the material parameters of the nanoplates obey a power-law variation in thickness and(ii) the uniform porosity exists in the nanoplates.The combined effects of viscoelasticity and shear deformation are considered by using the Kelvin-Voigt viscoelastic model and the refined higher-order shear deformation theory.The scale effects of the nanoplates are captured by employing nonlocal strain gradient theory(NSGT).The motion equations are calculated in accordance with Hamilton’s principle.Finally,the dispersion characteristics of the nanoplates are numerically determined by using a harmonic solution.The results indicate that the nonlocal parameters(NLPs) and length scale parameters(LSPs) have exactly the opposite effects on the wave frequency.In addition,it is found that the effect of porosity volume fractions(PVFs) on the wave frequency depends on the gradient indices and damping coefficients.When these two values are small,the wave frequency increases with the volume fraction.By contrast,at larger gradient index and damping coefficient values,the wave frequency decreases as the volume fraction increases.
文摘In this work,a series of BiOBr nanoplates with oxygen vacancies(OVs)were synthesized by a solvothermal method using a water/ethylene glycol solution.The number of OVs and facets of BiOBr were tuned by changing the water/ethylene glycol ratio.Although the role of OVs in photocatalysis has been investigated,the underlying mechanisms of charge transfer and reactant activation remain unknown.To unravel the effect of OVs on the reactant activation and photocatalytic NO oxidation process,in situ diffuse reflectance infrared Fourier transform spectroscopy,so‐called DRIFTS,and theoretical calculations were performed and their results combined.The photocatalytic efficiency of the as‐prepared BiOBr was significantly increased by increasing the amount of OVs.The oxygen vacancies had several effects on the photocatalysts,including the introduction of intermediate energy levels that enhanced light absorption,promoted electron transfer,acted as active sites for catalytic reaction and the activation of oxygen molecules,and facilitated the conversion of the intermediate products to the final product,thus increasing the overall visible light photocatalysis efficiency.The present work provides new insights into the understanding of the role of OVs in photocatalysts and the mechanism of photocatalytic NO oxidation.
基金support of the National Nat-ural Science Foundation of China(21875129).
文摘Lyotropic liquid crystals(LLCs)produced by the self-assembly of surfactant in water represent an important class of highly ordered soft materials that have a wide range of applications.This study investigates the LLCs formed by a zwitterionic surfactant(tetradecyldimethylaminoxide,C 14 DMAO)in water.The organization of C 14 DMAO within the LLCs was determined based on a detailed analysis of small-angle X-ray scattering measure-ments and polarized microscopy observations of a typical sample.Additional to the singe-phase region,which has a hexagonal organization,several two-phase regions were observed,exhibiting the coexistence of hexago-nal/cubic,cubic/lamellar,and hexagonal/lamellar phases.The phase behavior showed an obvious dependence on temperature,with more pronounced two-phase regions at lower temperatures.Using the LLCs as a matrix,Au nanospheres,nanoellipsoids,and nanorods were prepared without requiring additional reducing reagents.These three-and one-dimensional Au nanomaterials could be converted to two-dimensional plates via the introduc-tion of a small amount of cationic surfactant to the LLCs,such as cetyltrimethylammonium bromide(CTAB)and 1-hexadecyl-3-methylimidazolium bromide([C 16 MIm]B),which showed pronounced surface-enhanced Raman scattering activity towards solid rhodamine.The LLCs loaded with CTAB(or[C 16 MIm]B)and HAuCl 4 exhibited slightly different structures and mechanical strength from the original LLCs,thereby forming a new class of highly crowded colloidal materials.
