针对光固化Al2O3陶瓷在脱脂烧结后易形成孔洞、力学性能差的问题,系统研究了石墨烯添加对陶瓷浆料流变性、沉降性、固化行为及烧结体力学性能的影响。采用γ-缩水甘油醚氧丙基三甲氧基硅烷(KH560)对Al2O3粉体进行表面改性,并加入不同含...针对光固化Al2O3陶瓷在脱脂烧结后易形成孔洞、力学性能差的问题,系统研究了石墨烯添加对陶瓷浆料流变性、沉降性、固化行为及烧结体力学性能的影响。采用γ-缩水甘油醚氧丙基三甲氧基硅烷(KH560)对Al2O3粉体进行表面改性,并加入不同含量的石墨烯,制备高固相、低粘度的光固化浆料。通过傅里叶红外光谱、旋转流变仪、沉降试验及Beer-Lambert模型分析,优化了浆料配方与光固化工艺参数。结果表明:当KH560含量为2.5wt%、石墨烯含量为0.01wt%时,浆料粘度最低、沉降分层最少;在曝光时间4 s条件下,添加0.01wt%石墨烯的浆料透射深度为382μm,临界曝光能量为44.3 m J/cm2。经1750℃烧结后,陶瓷零件致密度达99.7%,弯曲强度为27.61 MPa,维氏硬度为13.45GPa。石墨烯通过位阻效应及裂纹偏转机制有效促进了烧结致密化并改善了力学性能。本研究为光固化增材制造高致密、高性能氧化铝陶瓷提供了试验依据。展开更多
P2型层状过渡金属氧化物(P2-NaxTMO2)因其优异的循环稳定性和倍率性能,成为钠离子电池正极材料的有力候选者。然而,其在高电压下的不可逆相变和固有低理论容量问题,阻碍了实际应用。本研究工作提出高熵策略与双相结构的协同设计...P2型层状过渡金属氧化物(P2-NaxTMO2)因其优异的循环稳定性和倍率性能,成为钠离子电池正极材料的有力候选者。然而,其在高电压下的不可逆相变和固有低理论容量问题,阻碍了实际应用。本研究工作提出高熵策略与双相结构的协同设计来克服这些挑战。通过在P2相高熵基体中引入O3相,构建新型P2/O3双相高熵层状氧化物Na0.70Ni0.25Mn0.35Co0.15Fe0.05Ti0.20O2(简称Na0.70NMCFT)。其中,高熵设计通过构型熵稳定效应有效抑制P2相的不可逆相变,而O3相则通过协同作用弥补容量不足并提升循环稳定性。此外,双相组分之间的相互作用进一步促进P2-O3与P2-P3相变的高度可逆性。Na0.70NMCFT在1C倍率下的初始放电容量为102.08 mAhg-1,200次循环后容量保持率达88.15%,表明具有优异的循环稳定性。更重要的是,即使在10C的高倍率下,Na0.70NMCFT仍能提供85.67 mAh g-1的初始放电比容量,并在1000次循环后容量保持率达70%。本工作证实双相高熵设计在提升钠离子电池正极性能中的关键作用,为开发先进钠离子电池正极材料提供了新思路。展开更多
Magnesium hydride serves as a promising solid-state hydrogen storage material owing to its high potential.However,its practical applications are constrained by the high enthalpy of hydrogen absorption and slow kinetic...Magnesium hydride serves as a promising solid-state hydrogen storage material owing to its high potential.However,its practical applications are constrained by the high enthalpy of hydrogen absorption and slow kinetics.In this study,we prepared a Ni/Ti3O5@graphene oxide(GO)dual-heterojunction composite material via solvent heating,electrostatic adsorption,and calcination to improve the hydrogen storage capabilities of MgH2.Adding Ni/Ti3O5@GO to MgH2 lowered the initial dehydrogenation temperature of MgH2 to 183℃;at a dehydrogenation temperature of 275℃,6.4 wt.%of H2 escaped from the MgH2 bulk.In addition,the hydrogen storage material absorbed 1.8 wt.%H2 at 30℃ for 30 min.The calculated activation energy of dehydrogenation was 48.221±0.141 kJ·mol-1,which was significantly lower than that of the ball-milled MgH2(112.63±1.44 kJ·mol-1).Mechanistic analysis results revealed that the heterojunction constructed from the multiphase compound system provided a large number of active sites and hydrogen diffusion routes,resulting in a synergistic catalytic effect that enhanced the hydrogen storage capacity of MgH2.In this work,we clarified the compositions of fuzzy interfaces in heterostructured materials by conducting ultraviolet photoelectron spectroscopy tests and identified key composite materials for the formation of heterojunctions.展开更多
Industrial fly ash-derived SiO2aerogel with abundant mesopores has an excellent ability to support active ingredients for constructing efficient and stable catalyst in electrochemical CO2reduction reaction(CO_(2...Industrial fly ash-derived SiO2aerogel with abundant mesopores has an excellent ability to support active ingredients for constructing efficient and stable catalyst in electrochemical CO2reduction reaction(CO2RR).However,how to select and arrange active sites on its surface poses significant challenges due to its non-conductive nature.Here,we subtly designed and synthesized multi-component architectures to achieve the high efficiency of CO2RR to CO.The embedding of active and amorphous nitrogen-doped carbon(NC)nanosheets on the surface and inside of SiO2aerogel ensures the charge transport on the catalyst surface,and Er2O3improves dissociation of H2O,enabling the supply of protons for CO2RR.Simultaneously,Er2O3-induced defects/vacancies,nanoclusters coordinated with N on amorphous NC and single Ni in NC play crucial role in enhancing adsorption and activation of CO2.Consequently,the Ni-Er2O3/NC-SiO2catalyst exhibits the maintenance of FECOhigher than 95%over a wide potential window(-0.22 to-1.12 V vs.RHE)in a flow cell with gas-liquid-solid electrode.This work not only provides an atomistic understanding of nature of active sites in CO2RR but also contributes to the secondary utilization of industrial fly ash for a carbon-neutral future.展开更多
Sodium-ion batteries(SIBs)are regarded as a promising alternative to lithium-ion batteries for grid-scale energy storage owing to their low cost and sustainability;however,their competitiveness is still limited by rel...Sodium-ion batteries(SIBs)are regarded as a promising alternative to lithium-ion batteries for grid-scale energy storage owing to their low cost and sustainability;however,their competitiveness is still limited by relatively low energy density.Here,we report a scalable Mn-Fe-Ni layered oxide with a compositional-structural dual-gradient(DG)architecture synthesized via a three-step co-precipitation method.By exploiting the opposite roles of high-ionic-potential Mn and low-ionic-potential Fe in stabilizing the P2 and O3 frameworks,respectively,a pure compositional Mn/Fe gradient is translated into a structural P2/O3 gradient with precisely guided synthesis conditions.The Fe-deficient surface effectively suppressed Fe4+-induced side reactions,while the stable P2-type shell and the enlarged R value of the O3 core further enhanced cycling stability during structural evolution.The optimized cathode delivered an energy density of 478 Wh kg-1at 4.2 V,with 82%capacity retention after 200 cycles in half cells and 91%retention after 1600 cycles in full cells.This study demonstrates a viable pathway for developing high-energy-density and long-lifetime cathodes for sodium-ion batteries.展开更多
As an emerging crystalline porous material,hydrogen bonded organic frameworks(HOFs)have enormous potential in photocatalytic field.However,poor stability and rapid recombination of photogenerated charges hinder their ...As an emerging crystalline porous material,hydrogen bonded organic frameworks(HOFs)have enormous potential in photocatalytic field.However,poor stability and rapid recombination of photogenerated charges hinder their practical application in photocatalytic H2O2production.To address the above challenges,this work employs a wet chemical method to grow In2S3nanosheets in situ on the surface of highly stable HOF nanorods(PFC-1),resulting in a novel inorganic/organic In2S3/PFC-1(IP)S-scheme heterojunction.The optimal IP composite achieves a significantly improved photocatalytic H2O2evolution rate of 3.78 mmol g-1h-1,which is 2.9-and 3.7-fold than that of In2S3and PFC-1,respectively.The elevated visible-light absorption,abundant active sites,and effective charge separation of IP S-scheme heterojunction result in the improvement in photocatalytic performance.Additionally,photocatalytic H2O2production of IP goes through a two-electron O2 reduction reaction pathway.This work offers a novel strategy for the fabrication of efficient HOF-based S-scheme heterostructures and their application in photocatalytic field.展开更多
Oxygen deficiency is known to critically influence the superconductivity of La3Ni2O7-δ.However,precise control of oxygen content to mitigate such deficiencies remains a significant challenge.In this work,we ...Oxygen deficiency is known to critically influence the superconductivity of La3Ni2O7-δ.However,precise control of oxygen content to mitigate such deficiencies remains a significant challenge.In this work,we synthesized high-oxygencontent La3Ni2O7+δpolycrystals via high-pressure oxygen annealing with the oxygen stoichiometry(δ)successfully tuned by varying the amount of KClO4.The obtained samples La3Ni2O7.16and La3Ni2O7.38exhibit metallic behavior at ambient pressure.We further conducted a comprehensive investigation into the pressure-induced superconductivity and atomic structure.STEM imaging revealed large-area bilayer-phase stacking in La3Ni2O7.16,while La3Ni2O7.38showed noticeable intergrowth with other Ruddlesden-Popper(R-P)phases.Notably,the critical pressure in La3Ni2O7.16is substantially reduced,though its critical temperature(Tc)is lower than that of as-grown samples.In contrast,only a weak superconducting signal was detected in higher oxygen content sample La3Ni2O7.38likely due to the intergrowth with other R-P phases,nonnegligible interstitial oxygen,or an increased fraction of the tetragonal phase.Our findings provide a viable pathway for optimizing nickelate superconductivity and offer insights into the fundamental mechanisms governing superconductivity in these materials.展开更多
摘要针对光固化Al2O3陶瓷在脱脂烧结后易形成孔洞、力学性能差的问题,系统研究了石墨烯添加对陶瓷浆料流变性、沉降性、固化行为及烧结体力学性能的影响。采用γ-缩水甘油醚氧丙基三甲氧基硅烷(KH560)对Al2O3粉体进行表面改性,并加入不同含量的石墨烯,制备高固相、低粘度的光固化浆料。通过傅里叶红外光谱、旋转流变仪、沉降试验及Beer-Lambert模型分析,优化了浆料配方与光固化工艺参数。结果表明:当KH560含量为2.5wt%、石墨烯含量为0.01wt%时,浆料粘度最低、沉降分层最少;在曝光时间4 s条件下,添加0.01wt%石墨烯的浆料透射深度为382μm,临界曝光能量为44.3 m J/cm2。经1750℃烧结后,陶瓷零件致密度达99.7%,弯曲强度为27.61 MPa,维氏硬度为13.45GPa。石墨烯通过位阻效应及裂纹偏转机制有效促进了烧结致密化并改善了力学性能。本研究为光固化增材制造高致密、高性能氧化铝陶瓷提供了试验依据。
摘要P2型层状过渡金属氧化物(P2-NaxTMO2)因其优异的循环稳定性和倍率性能,成为钠离子电池正极材料的有力候选者。然而,其在高电压下的不可逆相变和固有低理论容量问题,阻碍了实际应用。本研究工作提出高熵策略与双相结构的协同设计来克服这些挑战。通过在P2相高熵基体中引入O3相,构建新型P2/O3双相高熵层状氧化物Na0.70Ni0.25Mn0.35Co0.15Fe0.05Ti0.20O2(简称Na0.70NMCFT)。其中,高熵设计通过构型熵稳定效应有效抑制P2相的不可逆相变,而O3相则通过协同作用弥补容量不足并提升循环稳定性。此外,双相组分之间的相互作用进一步促进P2-O3与P2-P3相变的高度可逆性。Na0.70NMCFT在1C倍率下的初始放电容量为102.08 mAhg-1,200次循环后容量保持率达88.15%,表明具有优异的循环稳定性。更重要的是,即使在10C的高倍率下,Na0.70NMCFT仍能提供85.67 mAh g-1的初始放电比容量,并在1000次循环后容量保持率达70%。本工作证实双相高熵设计在提升钠离子电池正极性能中的关键作用,为开发先进钠离子电池正极材料提供了新思路。
基金supported by the National Natural Science Foundation of China[grant number U24A2044]Science and Technology Major Program of Guangxi Province[grant number GUIKEAA24206007].
摘要Magnesium hydride serves as a promising solid-state hydrogen storage material owing to its high potential.However,its practical applications are constrained by the high enthalpy of hydrogen absorption and slow kinetics.In this study,we prepared a Ni/Ti3O5@graphene oxide(GO)dual-heterojunction composite material via solvent heating,electrostatic adsorption,and calcination to improve the hydrogen storage capabilities of MgH2.Adding Ni/Ti3O5@GO to MgH2 lowered the initial dehydrogenation temperature of MgH2 to 183℃;at a dehydrogenation temperature of 275℃,6.4 wt.%of H2 escaped from the MgH2 bulk.In addition,the hydrogen storage material absorbed 1.8 wt.%H2 at 30℃ for 30 min.The calculated activation energy of dehydrogenation was 48.221±0.141 kJ·mol-1,which was significantly lower than that of the ball-milled MgH2(112.63±1.44 kJ·mol-1).Mechanistic analysis results revealed that the heterojunction constructed from the multiphase compound system provided a large number of active sites and hydrogen diffusion routes,resulting in a synergistic catalytic effect that enhanced the hydrogen storage capacity of MgH2.In this work,we clarified the compositions of fuzzy interfaces in heterostructured materials by conducting ultraviolet photoelectron spectroscopy tests and identified key composite materials for the formation of heterojunctions.
基金National Natural Science Foundation of China(22468034,22162019,22261040)Key Research and Development Project of Ordos(YF20240062)Science and Technology Projects of Inner Mongolia Autonomous Region(2021GG0195)。
摘要Industrial fly ash-derived SiO2aerogel with abundant mesopores has an excellent ability to support active ingredients for constructing efficient and stable catalyst in electrochemical CO2reduction reaction(CO2RR).However,how to select and arrange active sites on its surface poses significant challenges due to its non-conductive nature.Here,we subtly designed and synthesized multi-component architectures to achieve the high efficiency of CO2RR to CO.The embedding of active and amorphous nitrogen-doped carbon(NC)nanosheets on the surface and inside of SiO2aerogel ensures the charge transport on the catalyst surface,and Er2O3improves dissociation of H2O,enabling the supply of protons for CO2RR.Simultaneously,Er2O3-induced defects/vacancies,nanoclusters coordinated with N on amorphous NC and single Ni in NC play crucial role in enhancing adsorption and activation of CO2.Consequently,the Ni-Er2O3/NC-SiO2catalyst exhibits the maintenance of FECOhigher than 95%over a wide potential window(-0.22 to-1.12 V vs.RHE)in a flow cell with gas-liquid-solid electrode.This work not only provides an atomistic understanding of nature of active sites in CO2RR but also contributes to the secondary utilization of industrial fly ash for a carbon-neutral future.
基金National Natural Science Foundation(NNSF)of China(No.52572267)Guangdong Basic and Applied Basic Research Foundation(2023A1515140126)+1 种基金Ministry of Science and Technology of Guangdong Province(2023B0909020001)Guangdong High-level Innovation Institute Project(2021B0909050001)。
摘要Sodium-ion batteries(SIBs)are regarded as a promising alternative to lithium-ion batteries for grid-scale energy storage owing to their low cost and sustainability;however,their competitiveness is still limited by relatively low energy density.Here,we report a scalable Mn-Fe-Ni layered oxide with a compositional-structural dual-gradient(DG)architecture synthesized via a three-step co-precipitation method.By exploiting the opposite roles of high-ionic-potential Mn and low-ionic-potential Fe in stabilizing the P2 and O3 frameworks,respectively,a pure compositional Mn/Fe gradient is translated into a structural P2/O3 gradient with precisely guided synthesis conditions.The Fe-deficient surface effectively suppressed Fe4+-induced side reactions,while the stable P2-type shell and the enlarged R value of the O3 core further enhanced cycling stability during structural evolution.The optimized cathode delivered an energy density of 478 Wh kg-1at 4.2 V,with 82%capacity retention after 200 cycles in half cells and 91%retention after 1600 cycles in full cells.This study demonstrates a viable pathway for developing high-energy-density and long-lifetime cathodes for sodium-ion batteries.
摘要As an emerging crystalline porous material,hydrogen bonded organic frameworks(HOFs)have enormous potential in photocatalytic field.However,poor stability and rapid recombination of photogenerated charges hinder their practical application in photocatalytic H2O2production.To address the above challenges,this work employs a wet chemical method to grow In2S3nanosheets in situ on the surface of highly stable HOF nanorods(PFC-1),resulting in a novel inorganic/organic In2S3/PFC-1(IP)S-scheme heterojunction.The optimal IP composite achieves a significantly improved photocatalytic H2O2evolution rate of 3.78 mmol g-1h-1,which is 2.9-and 3.7-fold than that of In2S3and PFC-1,respectively.The elevated visible-light absorption,abundant active sites,and effective charge separation of IP S-scheme heterojunction result in the improvement in photocatalytic performance.Additionally,photocatalytic H2O2production of IP goes through a two-electron O2 reduction reaction pathway.This work offers a novel strategy for the fabrication of efficient HOF-based S-scheme heterostructures and their application in photocatalytic field.
基金Project supported by the National Key R&D Program of China(Grant No.2022YFA1403203)the National Natural Science Foundation of China(Grant Nos.12204007,12374133,12304162,and 12074002)+5 种基金the Key Scientific Research Foundation of the Education Department of Anhui Province(Grant No.2024AH050046)the Innovation Program for Quantum Science and Technology(Grant No.2021ZD0302802)Quantum Science and TechnologyNational Science and Technology Major Project(Grant No.2024ZD0301300)the Major Basic Program of Natural Science Foundation of Shandong Province(Grant No.ZR2021ZD01)the Start-up Funding Program of Guangdong-Hong Kong-Macao Greater Bay Area Quantum Science Center(Grant No.QD2301003)Guangdong Provincial Quantum Science Strategic Initiative(Grant No.GDZX2401001)。
摘要Oxygen deficiency is known to critically influence the superconductivity of La3Ni2O7-δ.However,precise control of oxygen content to mitigate such deficiencies remains a significant challenge.In this work,we synthesized high-oxygencontent La3Ni2O7+δpolycrystals via high-pressure oxygen annealing with the oxygen stoichiometry(δ)successfully tuned by varying the amount of KClO4.The obtained samples La3Ni2O7.16and La3Ni2O7.38exhibit metallic behavior at ambient pressure.We further conducted a comprehensive investigation into the pressure-induced superconductivity and atomic structure.STEM imaging revealed large-area bilayer-phase stacking in La3Ni2O7.16,while La3Ni2O7.38showed noticeable intergrowth with other Ruddlesden-Popper(R-P)phases.Notably,the critical pressure in La3Ni2O7.16is substantially reduced,though its critical temperature(Tc)is lower than that of as-grown samples.In contrast,only a weak superconducting signal was detected in higher oxygen content sample La3Ni2O7.38likely due to the intergrowth with other R-P phases,nonnegligible interstitial oxygen,or an increased fraction of the tetragonal phase.Our findings provide a viable pathway for optimizing nickelate superconductivity and offer insights into the fundamental mechanisms governing superconductivity in these materials.