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
Y2O3-MgO nanocomposite ceramic,as a novel infrared window material,exhibits superior properties compared to traditional infrared window materials.To realize its engineering application in high-speed aircraft suc...Y2O3-MgO nanocomposite ceramic,as a novel infrared window material,exhibits superior properties compared to traditional infrared window materials.To realize its engineering application in high-speed aircraft such as unmanned aerial vehicles,the reliable joining between Y2O3-MgO nanocomposite ceramic and TC4 alloy is a key challenge.In this study,the surface of Y2O3-MgO nanocomposite ceramic was first clad in air using an Ag-CuO-Al2O3 filler,which achieved uniform spreading on the ceramic.Subsequently,vacuum brazing was successfully performed between the clad Y2O3-MgO nanocomposite ceramic and TC4 alloy using AgCu filler.The microstructure and mechanical properties of the brazed joints were studied in detail.The air-reactive cladding technique significantly improved wettability,reducing the wetting angle of the filler metal on Y2O3-MgO nanocomposite ceramic from 104°to 27°.The brazed joint interface treated with the Ag-CuO-Al2O3 cladding exhibited sound metallurgical bonding without defects.The main phases identified in the Y2O3-MgO ceramic-side reaction layer were Cu2Y2O5,Mg0.78Cu0.22O,and Y4Al2O9.Analysis and calculations reveal that Cu2Y2O5 and Mg0.78Cu0.22O are respectively formed by the reaction of CuO with Y2O3and MgO,while Y4Al2O9 results from the reaction between Al2O3 and Y2O3.The typical interfacial microstructure was:Y2O3-MgO/Cu2Y2O5+Mg0.78Cu0.22O+Y4Al2O9/CuxTi6-xO+Ag(s,s.)/Ti(s,s.)+Ti2Cu/TC4.The joint achieved a maximum shear strength of 66 MPa under optimal parameters of 24 mol%CuO in the cladding layer and a brazing parameters of 860°C for 20 min.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
Catalytic CO2methanation exhibited significant potential for carbon reduction and energy storage,but still faced tough challenges due to poor abilities for CO2activation and oxygenate hydrogenation at low temper...Catalytic CO2methanation exhibited significant potential for carbon reduction and energy storage,but still faced tough challenges due to poor abilities for CO2activation and oxygenate hydrogenation at low temperatures.Herein,an inverse Nd2O3/Ni catalyst with Ni‑O‑Nd structures as catalytically active sites was facilely constructed.It achieved>80%CO2conversion with a CH4space‑time yield up to 143.4 mmol gcat-1h-1at 225℃and 1 bar,which far exceeded its counterpart(Nd2O3+Ni,27.8 mmol h-1),representing one of the state‑of‑the‑art CO2methanation catalysts.Systematic characterizations revealed that the well‑dispersed Nd species on Ni substrate over inverse Nd2O3/Ni enhanced Ni‑Nd2O3interaction and promoted the formation of Ni‑O‑Nd interface.Then,its surface basicity and local environment of Ni was greatly optimized,thus enhancing CO2adsorption and oxygenate hydrogenation abilities.In situ spectra and DFT calculations revealed that instead of the sole carbonyl pathway over Nd2O3+Ni,the Ni‑O‑Nd interface over the inverse Nd2O3/Ni brought a supplementary formate pathway with low energy barriers.Besides,it enabled lower energy barriers for CO2dissociation(0.30 vs 0.61 eV)and CO∗hydrogenation(0.70 vs 0.84 eV).Consequently,CO2activation and oxygenate hydrogenation ability over this inverse catalyst could be greatly enhanced,contributing to its excellent activity.展开更多
Supercritical fluids play a crucial role in material transport within Earth's deep interior.Investigating the pressure-dependent atomic structures and transport properties of such fluids is essential for understan...Supercritical fluids play a crucial role in material transport within Earth's deep interior.Investigating the pressure-dependent atomic structures and transport properties of such fluids is essential for understanding their petrological,chemical,and geophysical behaviors.In this study,we employed first-principles molecular dynamics simulations to explore the structures,self-diffusion coefficients(D),and viscosities(η)of supercritical NaAlSi3O8-H2O fluids under conditions of 2000 K and 3-10 GPa,with water contents of 30 wt% and 50 wt%.Our calculations indicate that at a water content of 30 wt%,Q2 and Q3 exhibit a certain degree of positive and negative pressure dependence,respectively,while other Qn species(n represents the number of bridging oxygens connected to Si/Al)show minimal changes.At a water content of 50 wt%,Q2 and Q0 exhibit a certain degree of positive and negative pressure dependence,respectively,while other Qn species show minimal changes.At both water contents,Si-O-H and molecular water in the system exhibit negative pressure dependence,suggesting that the migration of supercritical fluids from deep to shallow regions is accompanied by the release of water.The self-diffusion coefficients in the supercritical NaAlSi3O8-H2O fluid follow the order DNa≈DH>DO>DAl≈DSi,with an overall weak negative pressure dependence.By comparing the viscosities of anhydrous and hydrous silicate melts from previous studies,we found that the addition of water caused a transition from negative to positive pressure dependence of viscosity,corresponding to a structural change from polymerization to depolymerization.Additionally,we calculated the fluid mobility Δp/η of supercritical NaAlSi3O8-H2O fluids and found that their mobility is several orders of magnitude higher than that of basalt melt and is also significantly greater than that of carbonate melt.As supercritical fluids ascend from deeper to shallower regions,their mobility is further enhanced,significantly contributing to the transport of elements from subducting slabs to the overlying mantle wedge.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。
基金financial support from the National Natural Science Foundation of China(Grant Nos.U2167216,52504408,and 52475335)the China Postdoctoral Science Foundation Funded Project(Grant No.2024M754181)。
摘要Y2O3-MgO nanocomposite ceramic,as a novel infrared window material,exhibits superior properties compared to traditional infrared window materials.To realize its engineering application in high-speed aircraft such as unmanned aerial vehicles,the reliable joining between Y2O3-MgO nanocomposite ceramic and TC4 alloy is a key challenge.In this study,the surface of Y2O3-MgO nanocomposite ceramic was first clad in air using an Ag-CuO-Al2O3 filler,which achieved uniform spreading on the ceramic.Subsequently,vacuum brazing was successfully performed between the clad Y2O3-MgO nanocomposite ceramic and TC4 alloy using AgCu filler.The microstructure and mechanical properties of the brazed joints were studied in detail.The air-reactive cladding technique significantly improved wettability,reducing the wetting angle of the filler metal on Y2O3-MgO nanocomposite ceramic from 104°to 27°.The brazed joint interface treated with the Ag-CuO-Al2O3 cladding exhibited sound metallurgical bonding without defects.The main phases identified in the Y2O3-MgO ceramic-side reaction layer were Cu2Y2O5,Mg0.78Cu0.22O,and Y4Al2O9.Analysis and calculations reveal that Cu2Y2O5 and Mg0.78Cu0.22O are respectively formed by the reaction of CuO with Y2O3and MgO,while Y4Al2O9 results from the reaction between Al2O3 and Y2O3.The typical interfacial microstructure was:Y2O3-MgO/Cu2Y2O5+Mg0.78Cu0.22O+Y4Al2O9/CuxTi6-xO+Ag(s,s.)/Ti(s,s.)+Ti2Cu/TC4.The joint achieved a maximum shear strength of 66 MPa under optimal parameters of 24 mol%CuO in the cladding layer and a brazing parameters of 860°C for 20 min.
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.
基金supported by the Technology Project of South-west United Graduate School of Yunnan Province(No.202302AQ370002)Young Elite Scientists Sponsorship Program by China Association for Science and Technology(No.YESS20230169)+1 种基金the National Natural Science Foun dation of China(No.22276081)Chongqing Research Institute Performance Incentive Guidance Special Project(No.CSTB2023JXJL-YFX0074)。
摘要Catalytic CO2methanation exhibited significant potential for carbon reduction and energy storage,but still faced tough challenges due to poor abilities for CO2activation and oxygenate hydrogenation at low temperatures.Herein,an inverse Nd2O3/Ni catalyst with Ni‑O‑Nd structures as catalytically active sites was facilely constructed.It achieved>80%CO2conversion with a CH4space‑time yield up to 143.4 mmol gcat-1h-1at 225℃and 1 bar,which far exceeded its counterpart(Nd2O3+Ni,27.8 mmol h-1),representing one of the state‑of‑the‑art CO2methanation catalysts.Systematic characterizations revealed that the well‑dispersed Nd species on Ni substrate over inverse Nd2O3/Ni enhanced Ni‑Nd2O3interaction and promoted the formation of Ni‑O‑Nd interface.Then,its surface basicity and local environment of Ni was greatly optimized,thus enhancing CO2adsorption and oxygenate hydrogenation abilities.In situ spectra and DFT calculations revealed that instead of the sole carbonyl pathway over Nd2O3+Ni,the Ni‑O‑Nd interface over the inverse Nd2O3/Ni brought a supplementary formate pathway with low energy barriers.Besides,it enabled lower energy barriers for CO2dissociation(0.30 vs 0.61 eV)and CO∗hydrogenation(0.70 vs 0.84 eV).Consequently,CO2activation and oxygenate hydrogenation ability over this inverse catalyst could be greatly enhanced,contributing to its excellent activity.
基金funded by National Natural Science Foundation of China(42373033,Yicheng Sun)Fundamental Research Funds for the Central Universities(B240201111,Yicheng Sun)。
摘要Supercritical fluids play a crucial role in material transport within Earth's deep interior.Investigating the pressure-dependent atomic structures and transport properties of such fluids is essential for understanding their petrological,chemical,and geophysical behaviors.In this study,we employed first-principles molecular dynamics simulations to explore the structures,self-diffusion coefficients(D),and viscosities(η)of supercritical NaAlSi3O8-H2O fluids under conditions of 2000 K and 3-10 GPa,with water contents of 30 wt% and 50 wt%.Our calculations indicate that at a water content of 30 wt%,Q2 and Q3 exhibit a certain degree of positive and negative pressure dependence,respectively,while other Qn species(n represents the number of bridging oxygens connected to Si/Al)show minimal changes.At a water content of 50 wt%,Q2 and Q0 exhibit a certain degree of positive and negative pressure dependence,respectively,while other Qn species show minimal changes.At both water contents,Si-O-H and molecular water in the system exhibit negative pressure dependence,suggesting that the migration of supercritical fluids from deep to shallow regions is accompanied by the release of water.The self-diffusion coefficients in the supercritical NaAlSi3O8-H2O fluid follow the order DNa≈DH>DO>DAl≈DSi,with an overall weak negative pressure dependence.By comparing the viscosities of anhydrous and hydrous silicate melts from previous studies,we found that the addition of water caused a transition from negative to positive pressure dependence of viscosity,corresponding to a structural change from polymerization to depolymerization.Additionally,we calculated the fluid mobility Δp/η of supercritical NaAlSi3O8-H2O fluids and found that their mobility is several orders of magnitude higher than that of basalt melt and is also significantly greater than that of carbonate melt.As supercritical fluids ascend from deeper to shallower regions,their mobility is further enhanced,significantly contributing to the transport of elements from subducting slabs to the overlying mantle wedge.