Constructing heterojunctions and hollow multi-shelled structures can render materials with fascinating physicochemical properties,and have been regarded as two promising strategies to overcome the severe shuttling and...Constructing heterojunctions and hollow multi-shelled structures can render materials with fascinating physicochemical properties,and have been regarded as two promising strategies to overcome the severe shuttling and sluggish kinetics of polysulfide in lithium-sulfur(Li-S)batteries.However,a single strategy can only take limited effect.Modulating catalytic hosts with synergistic effects are urgently desired.Herein,Mn_(3)O_(4)-MnS heterogeneous multi-shelled hollow spheres are meticulously designed by controlled sulfuration of Mn2O3 hollow spheres,and then applied as advanced encapsulation hosts for Li-S batteries.Benefiting from the separated spatial confinement by hollow multi-shelled structure,ample exposed active sites and built-in electric field by heterogeneous interface,and synergistic effects between Mn_(3)O_(4)(strong adsorption)and MnS(fast conversion)components,the assembled battery achieves prominent rate capability and decent cyclability(0.016%decay per cycle at 2 C,1000 cycles).More crucially,satisfactory areal capacity reaches up to 7.1 mAh cm^(-2)even with high sulfur loading(8.0 mg cm^(-2))and lean electrolyte(E/S=4.0 pL mg^(-1))conditions.This work will provide inspiration for the rational design of hollow multi-shelled heterostructure for various electrocatalysis applications.展开更多
Multi-functionalization is the future development direction for protective coatings on metal surface,but has not yet been explored a lot.The effective integration of multiple functions into one material remains a huge...Multi-functionalization is the future development direction for protective coatings on metal surface,but has not yet been explored a lot.The effective integration of multiple functions into one material remains a huge challenge.Herein,a superhydrophobic multilayer coating integrated with multidimensional organic-inorganic components is designed on magnesium alloy via one-step plasma-induced thermal field assisted crosslinking deposition(PTCD)processing followed by after-thermal modification.Hard porous MgO ceramic layer and polytetrafluoroethylene(PTFE)nano-particles work as the bottom layer skeleton and filler components separately,forming an organic-inorganic multilayer structure,in which organic nano-particles can be crosslinked and cured to form a compact polymer-like outer layer with hierarchical surface textures.Remarkably,the chemical robustness after prolonged exposure to aqua regia,strong base and simulated seawater solution profits from polymer-like nanocomposite layer uniformly and compactly across the film bulk.Moreover,the self-similar multilayer structure coating endows it attractive functions of strong mechanical robustness(>100th cyclic rotary abrasion),stable and ultra-low friction coefficient(about 0.084),high-temperature endurance,and robust self-cleaning.The organic-inorganic multilayer coating also exhibits high insulating property with breakdown voltage of 1351.8±42.4 V,dielectric strength of 21.4±0.7 V/μm and resistivity of 3.2×10^(10)Ω·cm.The excellent multifunction benefits from ceramic bottom skeleton,the assembly and deposition of multidimensional nano-particles,and the synergistic effect of organic inorganic components.This study paves the way for designing next generation protective coating on magnesium alloy with great potential for multifunctional applications.展开更多
The lifetime and luminescenceefficiency o Light emitting diode(LED)tend to drop rapidly with the increasing P-N junction temperature(Tj).To enhancethe heat dissipationofaluminum alloy radiator for LED,a high emissivit...The lifetime and luminescenceefficiency o Light emitting diode(LED)tend to drop rapidly with the increasing P-N junction temperature(Tj).To enhancethe heat dissipationofaluminum alloy radiator for LED,a high emissivity and hydrophobic coatingwas fabricated bymicroarc oxidation(MAO)com-展开更多
Additively manufactured(AM)metallic materials commonly possess substantial tensile surface residual stress,which is detrimental to the load-bearing service behavior.Recently,we demonstrated that deep cryogenic treatme...Additively manufactured(AM)metallic materials commonly possess substantial tensile surface residual stress,which is detrimental to the load-bearing service behavior.Recently,we demonstrated that deep cryogenic treatment(DCT)is an effective method for improving the tensile properties of CoCrFeMnNi high-entropy alloy(HEA)samples fabricated by laser melting deposition(LMD),by introducing high compressive residual stress and deformation microstructures without destroying the AM shape.However,carrying out the DCT in a single-step mode does not improve the residual stress gradients inherent from the LMD process,which are undesirable as the mechanical properties will not be homogeneous within the sample.In this work,we show that carrying out the DCT in a cyclic mode with repeated cryogenic cooling and reheating can significantly homogenize the residual stress in LMD-fabricated Co Cr Fe Mn Ni HEA,and improve tensile strength and ductility,compared with single-step DCT of the same cryogenic soaking duration.Under cyclic DCT,the thermal stress is re-elevated to a high value at each cryogenic cooling step,leading to the formation of denser and more intersecting reinforcing crystalline defects and hcp phase transformation,compared to single-step DCT of the same total cryogenic soaking duration in which the thermal stress relaxes towards a low value over time.The enhancement of defect formation in the cyclic mode of DCT also leads to more uniform residual stress distribution in the sample after the DCT.The results here provide important insights on optimizing DCT processes for post-fabrication improvement of mechanical properties of AM metallic net shapes.展开更多
Daylighting structures,including solar cells and building windows,utilize sunlight whilst suffering from undesired solar heat and outdoor dust contamination.A radiative cooling system that is transparent to sunlight a...Daylighting structures,including solar cells and building windows,utilize sunlight whilst suffering from undesired solar heat and outdoor dust contamination.A radiative cooling system that is transparent to sunlight and has a superhydrophobic surface would cool and clean the daylighting structures in a sustainable manner.However,the majority of the current daytime radiative cooling systems were designed to fully reflect the incident sunlight to maximize the cooling power.In this work,we optimized both the sunlight transmission and infrared thermal irradiation by modeling the size-dependent scattering and absorption of light by SiO_(2)spheres embedded in a polymer matrix,we found that the use of nanospheres(20 nm)enabled both high sunlight transmittance(>90%)and infrared emissivity(-0.85).This theoretical prediction was confirmed by experimental measurements of a solution-processed nanocomposite film.When coated on a solar cell,the as-prepared film not only preserved the power conversion efficiency of the cell(14.71%,uncoated cell has an efficiency of 14.79%)but also radiatively cooled the cell by up to 5℃under direct sunlight.This reduction of the operating temperature of the solar cell further enhanced its electrical power output,evidenced by an increase in the equilibrium temperature of the LED load by about 14℃.The nanoscale textured surface formed by the nanospheres further led to superhydrophobicity and thus excellent self-cleaning performance(efficient removal of dust by wind and/or water droplets).展开更多
基金The support from the National Natural Science Foundation of China(No.51971083)the Natural Science Foundation of Heilongjiang Province,China(YQ 2020E007)is gratefully acknowledgedfinancially sponsored by Heilongjiang Touyan Team Program.
文摘Constructing heterojunctions and hollow multi-shelled structures can render materials with fascinating physicochemical properties,and have been regarded as two promising strategies to overcome the severe shuttling and sluggish kinetics of polysulfide in lithium-sulfur(Li-S)batteries.However,a single strategy can only take limited effect.Modulating catalytic hosts with synergistic effects are urgently desired.Herein,Mn_(3)O_(4)-MnS heterogeneous multi-shelled hollow spheres are meticulously designed by controlled sulfuration of Mn2O3 hollow spheres,and then applied as advanced encapsulation hosts for Li-S batteries.Benefiting from the separated spatial confinement by hollow multi-shelled structure,ample exposed active sites and built-in electric field by heterogeneous interface,and synergistic effects between Mn_(3)O_(4)(strong adsorption)and MnS(fast conversion)components,the assembled battery achieves prominent rate capability and decent cyclability(0.016%decay per cycle at 2 C,1000 cycles).More crucially,satisfactory areal capacity reaches up to 7.1 mAh cm^(-2)even with high sulfur loading(8.0 mg cm^(-2))and lean electrolyte(E/S=4.0 pL mg^(-1))conditions.This work will provide inspiration for the rational design of hollow multi-shelled heterostructure for various electrocatalysis applications.
基金The partial supports from the NSFC grant nos.51571077 and 51621091National Basic Science Research Program(2012CB933900)+2 种基金Advanced Space Propulsion Laboratory of BICE and Beijing Engineering Research Center of Efficient and Green Aerospace Propulsion Technology(Lab ASP-2020-05)Aviation Science Foundation of China(NO.20163877014)the Fundamental Research Funds for the Central Universities(HIT.BRETIII.201202)。
文摘Multi-functionalization is the future development direction for protective coatings on metal surface,but has not yet been explored a lot.The effective integration of multiple functions into one material remains a huge challenge.Herein,a superhydrophobic multilayer coating integrated with multidimensional organic-inorganic components is designed on magnesium alloy via one-step plasma-induced thermal field assisted crosslinking deposition(PTCD)processing followed by after-thermal modification.Hard porous MgO ceramic layer and polytetrafluoroethylene(PTFE)nano-particles work as the bottom layer skeleton and filler components separately,forming an organic-inorganic multilayer structure,in which organic nano-particles can be crosslinked and cured to form a compact polymer-like outer layer with hierarchical surface textures.Remarkably,the chemical robustness after prolonged exposure to aqua regia,strong base and simulated seawater solution profits from polymer-like nanocomposite layer uniformly and compactly across the film bulk.Moreover,the self-similar multilayer structure coating endows it attractive functions of strong mechanical robustness(>100th cyclic rotary abrasion),stable and ultra-low friction coefficient(about 0.084),high-temperature endurance,and robust self-cleaning.The organic-inorganic multilayer coating also exhibits high insulating property with breakdown voltage of 1351.8±42.4 V,dielectric strength of 21.4±0.7 V/μm and resistivity of 3.2×10^(10)Ω·cm.The excellent multifunction benefits from ceramic bottom skeleton,the assembly and deposition of multidimensional nano-particles,and the synergistic effect of organic inorganic components.This study paves the way for designing next generation protective coating on magnesium alloy with great potential for multifunctional applications.
文摘The lifetime and luminescenceefficiency o Light emitting diode(LED)tend to drop rapidly with the increasing P-N junction temperature(Tj).To enhancethe heat dissipationofaluminum alloy radiator for LED,a high emissivity and hydrophobic coatingwas fabricated bymicroarc oxidation(MAO)com-
基金the National Natural Science Foundation of China(Nos.52171154,and 51871076)the National Key Research and Development Programs of China(Nos.2018YFB1105200 and 2019YFA0209904)+1 种基金the Guangdong Province Basic and Applied Research Key Projects(Nos.2020190718102)the National Key R&D Programme,Ministry of Science and Technology of China(No.2019YFA0209)。
文摘Additively manufactured(AM)metallic materials commonly possess substantial tensile surface residual stress,which is detrimental to the load-bearing service behavior.Recently,we demonstrated that deep cryogenic treatment(DCT)is an effective method for improving the tensile properties of CoCrFeMnNi high-entropy alloy(HEA)samples fabricated by laser melting deposition(LMD),by introducing high compressive residual stress and deformation microstructures without destroying the AM shape.However,carrying out the DCT in a single-step mode does not improve the residual stress gradients inherent from the LMD process,which are undesirable as the mechanical properties will not be homogeneous within the sample.In this work,we show that carrying out the DCT in a cyclic mode with repeated cryogenic cooling and reheating can significantly homogenize the residual stress in LMD-fabricated Co Cr Fe Mn Ni HEA,and improve tensile strength and ductility,compared with single-step DCT of the same cryogenic soaking duration.Under cyclic DCT,the thermal stress is re-elevated to a high value at each cryogenic cooling step,leading to the formation of denser and more intersecting reinforcing crystalline defects and hcp phase transformation,compared to single-step DCT of the same total cryogenic soaking duration in which the thermal stress relaxes towards a low value over time.The enhancement of defect formation in the cyclic mode of DCT also leads to more uniform residual stress distribution in the sample after the DCT.The results here provide important insights on optimizing DCT processes for post-fabrication improvement of mechanical properties of AM metallic net shapes.
基金financially supported by the National Natural Science Foundation of China(Nos.52071114 and 52001100)the Aviation Science Foundation of China(No.20163877014)。
文摘Daylighting structures,including solar cells and building windows,utilize sunlight whilst suffering from undesired solar heat and outdoor dust contamination.A radiative cooling system that is transparent to sunlight and has a superhydrophobic surface would cool and clean the daylighting structures in a sustainable manner.However,the majority of the current daytime radiative cooling systems were designed to fully reflect the incident sunlight to maximize the cooling power.In this work,we optimized both the sunlight transmission and infrared thermal irradiation by modeling the size-dependent scattering and absorption of light by SiO_(2)spheres embedded in a polymer matrix,we found that the use of nanospheres(20 nm)enabled both high sunlight transmittance(>90%)and infrared emissivity(-0.85).This theoretical prediction was confirmed by experimental measurements of a solution-processed nanocomposite film.When coated on a solar cell,the as-prepared film not only preserved the power conversion efficiency of the cell(14.71%,uncoated cell has an efficiency of 14.79%)but also radiatively cooled the cell by up to 5℃under direct sunlight.This reduction of the operating temperature of the solar cell further enhanced its electrical power output,evidenced by an increase in the equilibrium temperature of the LED load by about 14℃.The nanoscale textured surface formed by the nanospheres further led to superhydrophobicity and thus excellent self-cleaning performance(efficient removal of dust by wind and/or water droplets).
