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
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
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
1.Indroduction In light of the global transition toward carbon neutrality,the development of mild-condition ammonia synthesis technologies has gained significant attention as a promising solution to address the inhere...1.Indroduction In light of the global transition toward carbon neutrality,the development of mild-condition ammonia synthesis technologies has gained significant attention as a promising solution to address the inherent limitations of the traditional Haber-Bosch approach,which remains highly energy-intensive due to the extreme operation conditions(above 350℃ and over 10 MPa)required to activate the robust N≡N bond(945 kJ mol-1).Furthermore,the process is carbon-intensive,as its primary hydrogen source is derived from hydrocarbon reforming with high carbon emissions[1,2].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
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.
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the financial support from the National Natural Science Foundation of China(Nos.22588201,22225204 to D.D.,22472169 to L.Y.,and 22427801 to W.L.)the Outstanding Member of CAS Youth Innovation Promotion Association(No.Y2023053 to W.L.)the DICP&SIA Joint Project(No.UN202401 to W.L.)。
摘要1.Indroduction In light of the global transition toward carbon neutrality,the development of mild-condition ammonia synthesis technologies has gained significant attention as a promising solution to address the inherent limitations of the traditional Haber-Bosch approach,which remains highly energy-intensive due to the extreme operation conditions(above 350℃ and over 10 MPa)required to activate the robust N≡N bond(945 kJ mol-1).Furthermore,the process is carbon-intensive,as its primary hydrogen source is derived from hydrocarbon reforming with high carbon emissions[1,2].
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.