The effectiveness of dual-doping as a method of improving the conductivity of sulfide solid electrolytes(SEs)is not in doubt;however,the atomic-level mechanisms underpinning these enhancements remain elusive.In this s...The effectiveness of dual-doping as a method of improving the conductivity of sulfide solid electrolytes(SEs)is not in doubt;however,the atomic-level mechanisms underpinning these enhancements remain elusive.In this study,we investigate the atomic mechanisms associated with the high ionic conductivity of the Li_(7)P_(3)S_(11)(LPS)SE and its response to Ag/Cl dual dopants.Synthesis and electrochemical characterizations show that the 0.2 M AgCl-doped LPS(Li_(6.8)P_(3)Ag_(0.1)S_(10.9)Cl_(0.1))exhibited an over 80%improvement in ionic conductivity compared with the undoped LPS.The atomic-level structures responsible for the enhanced conductivity were generated by a set of experiment and simulation techniques:synchrotron X-ray diffractometry,Rietveld refinement,density functional theory,and artificial neural network-based molecular dynamics simulations.This thorough characterization highlights the role of dual dopants in altering the structure and ionic conductivity.We found that the PS_(4) and P_(2)S_(7) structural motifs of LPS undergo transformation into various PS_(x) substructures.These changes in the substructures,in conjunction with the paddle-wheel effect,enable rapid Li migration.The dopant atoms serve to enhance the flexibility of PS_(4)–P_(2)S_(7) polyhedral frameworks,consequently enhancing the ionic conductivity.Our study elucidates a clear structure–conductivity relationship for the dual-doped LPS,providing a fundamental guideline for the development of sulfide SEs with superior conductivity.展开更多
Nb_(2)O_(5)nanoparticles with an average particle size of 10 nm supported on a rhombic dodecahedral metal organic framework(MOF)were successfully synthesized by a facile one-pot hydrothermal reaction and subsequent ca...Nb_(2)O_(5)nanoparticles with an average particle size of 10 nm supported on a rhombic dodecahedral metal organic framework(MOF)were successfully synthesized by a facile one-pot hydrothermal reaction and subsequent calcination process.Experimental results demonstrated that the prepared catalyst drastically improved the hydrogen storage behavior of MgH_(2).7 wt%Nb_(2)O_(5)@MOF doped MgH_(2)started to desorb hydrogen at 181.9℃and 6.2 wt%hydrogen could be released within 2.6 min and 6.3 min at 275℃and 250℃,respectively.The fully dehydrogenated composite also displayed excellent hydrogenation by decreasing the onset absorption temperature to 25℃and taking up4.9 wt%and 6.5 wt%hydrogen within 6 min at 1750C and 1500C,respectively.Moreover,the corresponding activation energy was calculated to be 75.57±4.16 kJ mol^(-1)for desorption reaction and 51.38±1.09 kJ mol^(-1)for absorption reaction.After 20 cycles,0.5 wt%hydrogen capacity was lost for the MgH_(2)+7 wt%Nb_(2)O_(5)@MOF composite,much lower than 1.5 wt%of the MgH_(2)+7 wt%Nb_(2)O_(5)composite.However,the addition of Nb_(2)O_(5)@MOF had limited effect on reducing the dehydrogenation enthalpy of MgH_(2).Microstructure analysis revealed that Nb_(2)O_(5)particles were uniformly distributed on surface of the MgH_(2)matrix and synergistically improved the hydrogen storage property of MgH_(2)with MOF.展开更多
Porous cordierite ceramics were prepared from a mixture of coal fly ash and basic magnesium carbonate at 1100-1350℃. Porosity,flexural strength and thermal expansion coefficient of the samples sintered at 1300℃ were...Porous cordierite ceramics were prepared from a mixture of coal fly ash and basic magnesium carbonate at 1100-1350℃. Porosity,flexural strength and thermal expansion coefficient of the samples sintered at 1300℃ were estimated to be 26%,65 MPa and 4.21×10-6/ ℃ ,respectively. The kinetics of the formation progress was investigated by stepwise isothermal dilatometry (SID) accompanied with XRD,SEM and porosity measurement. It was found that the isothermal shrinkage data from SID could be well analyzed to get kinetic parameters according to the em-pirical rate equation developed by Makipirtti-Meng,dY/dt=nk(T)Y(1-Y)(Y/1-Y)1/n,where Y is the fractional shrinkage during the sintering process and n is a dimensionless component. The apparent activation energy △E values for 900-1000℃ and 1050-1150℃ were 1294 and 1778 kJ/mol,respectively.展开更多
The non-isothermal and isothermal crystallization kinetics of Zr_（72.5）Al_（10）Fe_（17.5） glassy alloy was investigated using differential scanning calorimeter（DSC）.Under non-isothermal heating condition,the pri...The non-isothermal and isothermal crystallization kinetics of Zr_（72.5）Al_（10）Fe_（17.5） glassy alloy was investigated using differential scanning calorimeter（DSC）.Under non-isothermal heating condition,the primary phase in the initial crystallization is Zr_6Al_2Fe phase and the final crystallized products consist of Zr_6Al_2Fe,Zr_2Fe and a-Zr phases.The apparent activation energy for crystallization estimated using the Kissinger method is 342.1 ±8.1 kJ/mol.The local activation energy decreased with the increase in the crystallization volume fraction during nonisothermal crystallization.Under isothermal heating condition,the average Avrami exponent of about 2.76 implies a mainly diffusion-controlled three-dimensional growth with an increasing nucleation rate.The local activation energy for isothermal crystallization shows a different variation trend from that for nonisothermal crystallization,indicating different nucleation-and-growth mechanisms for the two crystallizaiton conditions.展开更多
Copper complexes inspired by O_(2)-activating enzymes have been widely investigated as molecular water oxidation catalysts,capable of facile and reversible O─O bond formation and cleavage under mild conditions.In thi...Copper complexes inspired by O_(2)-activating enzymes have been widely investigated as molecular water oxidation catalysts,capable of facile and reversible O─O bond formation and cleavage under mild conditions.In this study,two copper phenanthroline complexes,namely,Cu(phen)and Cu(dophen),exhibit high turnover frequencies(TOFs)of 74±13 and(5.66±0.29)×10^(3)s^(−1)for water oxidation,respectively.Moreover,amino acid-functionalized carbon dots(CDs)were used to support the adhesion of the[Cu]complexes onto the electrode,significantly enhancing the TOFs of(2.80±0.12)×10^(3)and(4.11±0.24)×10^(4)s^(−1),respectively,exceeding the activity of photosystem II in nature.Remarkably,the amino acid-functionalized CDs provide a secondary sphere that mimics the catalytic microenvironment of the copper centre,which promotes proton-coupled electron transfer and O─O bond formation.Finally,the photovoltaic-electrolysis(PVE)system was established using CDs-supported Cu catalysts and commercial silicon solar panels,achieving a high solar-to-hydrogen efficiency of 11.59%under the illumination of AM 1.5 G.This represents the most efficient solar-driven water splitting system based on copper-based catalysts to date,introducing the biomimetic secondary sphere to a“proton-rocking”process for water oxidation catalysis and application of the PVE system.展开更多
Several nano material and reaction systems were in situ monitored with an electrochemical TEM wet cell set up. In a 1 g/L sliver particle aqueous solution, the particles were observed to be ca. 10 nm sized, in both di...Several nano material and reaction systems were in situ monitored with an electrochemical TEM wet cell set up. In a 1 g/L sliver particle aqueous solution, the particles were observed to be ca. 10 nm sized, in both discrete particle and nano cluster forms. The silver particles were attached to the 50 nm-thick Si3N4 windows of the wet cell and could not move freely in the liquid. With a SIC14 liquid loaded in the wet cell, silicon nano materials were controllably grown on the wet cell windows by means of a liquid phase electron beam induced deposition （EBID） method. The deposited nano dots were nicely round-shaped, and demonstrated a power law growth dependency on beam exposure time in a log-log plot. In a NiCI2 solution/Ni system, both electrochemical deposition and dissolution of the nickel nano films were observed while applying electric biases on to the nickel electrodes in the wet cell. Instead of extensional growth on existing crystals, interestingly, it is more commonly observed that new nickel nano particles grow out in front of the existing film first and then merged into the film. The wet cell set up is demonstrated to be a versatile tool for nano liquid system research.展开更多
We present a facile and controllable method for the large-scale fabrication of highly-ordered octahedral Fe3O4 colloidal ＂single crystals＂ without the assistance of a substrate. Oleic acid is used to reduce the solu...We present a facile and controllable method for the large-scale fabrication of highly-ordered octahedral Fe3O4 colloidal ＂single crystals＂ without the assistance of a substrate. Oleic acid is used to reduce the solubility of the nano-building blocks in colloidal solution and to induce a ＂crystallization＂ process. Our colloidal crystals are of multimicron size and show typical crystallographic characteristics. They have a very robust structure and can serve as a novel ordered magnetic mesoporous material with a relatively narrow pore size distribution. The sample possesses an extremely high Verwey transition temperature （Tv） of 100 K and a high saturation magnetization （Ms） of 86 emu/g at 5 K based on its good crystallinity, as well as the interparticle dipolar interaction behavior arising from its unique structure. Electrochemical measurements have demonstrated the excellent capacity of the mesoporous colloidal crystals when used in lithium-ion batteries.展开更多
基金National Research Foundation of Korea,Grant/A ward Numbers:MEST,NRF-2021R1A2C2009596Engineeringand Physical Sciences Research Council,Grant/A ward Numbers:EP/R029431,EP/P020194,EP/T022213+1 种基金Korea government(Ministry of Science and ICT,MSIT),Grant/Award Number:RS-2023-00236572European Research Council,ERC,Grant/Award Numbers:EP/R029431,EP/P020194,EP/T022213。
文摘The effectiveness of dual-doping as a method of improving the conductivity of sulfide solid electrolytes(SEs)is not in doubt;however,the atomic-level mechanisms underpinning these enhancements remain elusive.In this study,we investigate the atomic mechanisms associated with the high ionic conductivity of the Li_(7)P_(3)S_(11)(LPS)SE and its response to Ag/Cl dual dopants.Synthesis and electrochemical characterizations show that the 0.2 M AgCl-doped LPS(Li_(6.8)P_(3)Ag_(0.1)S_(10.9)Cl_(0.1))exhibited an over 80%improvement in ionic conductivity compared with the undoped LPS.The atomic-level structures responsible for the enhanced conductivity were generated by a set of experiment and simulation techniques:synchrotron X-ray diffractometry,Rietveld refinement,density functional theory,and artificial neural network-based molecular dynamics simulations.This thorough characterization highlights the role of dual dopants in altering the structure and ionic conductivity.We found that the PS_(4) and P_(2)S_(7) structural motifs of LPS undergo transformation into various PS_(x) substructures.These changes in the substructures,in conjunction with the paddle-wheel effect,enable rapid Li migration.The dopant atoms serve to enhance the flexibility of PS_(4)–P_(2)S_(7) polyhedral frameworks,consequently enhancing the ionic conductivity.Our study elucidates a clear structure–conductivity relationship for the dual-doped LPS,providing a fundamental guideline for the development of sulfide SEs with superior conductivity.
基金fiscal funding from the National Natural Science Foundation of China(No.51801078)the Natural Science Foundation of Jiangsu Province(No.BK20180986)。
文摘Nb_(2)O_(5)nanoparticles with an average particle size of 10 nm supported on a rhombic dodecahedral metal organic framework(MOF)were successfully synthesized by a facile one-pot hydrothermal reaction and subsequent calcination process.Experimental results demonstrated that the prepared catalyst drastically improved the hydrogen storage behavior of MgH_(2).7 wt%Nb_(2)O_(5)@MOF doped MgH_(2)started to desorb hydrogen at 181.9℃and 6.2 wt%hydrogen could be released within 2.6 min and 6.3 min at 275℃and 250℃,respectively.The fully dehydrogenated composite also displayed excellent hydrogenation by decreasing the onset absorption temperature to 25℃and taking up4.9 wt%and 6.5 wt%hydrogen within 6 min at 1750C and 1500C,respectively.Moreover,the corresponding activation energy was calculated to be 75.57±4.16 kJ mol^(-1)for desorption reaction and 51.38±1.09 kJ mol^(-1)for absorption reaction.After 20 cycles,0.5 wt%hydrogen capacity was lost for the MgH_(2)+7 wt%Nb_(2)O_(5)@MOF composite,much lower than 1.5 wt%of the MgH_(2)+7 wt%Nb_(2)O_(5)composite.However,the addition of Nb_(2)O_(5)@MOF had limited effect on reducing the dehydrogenation enthalpy of MgH_(2).Microstructure analysis revealed that Nb_(2)O_(5)particles were uniformly distributed on surface of the MgH_(2)matrix and synergistically improved the hydrogen storage property of MgH_(2)with MOF.
基金financially supported by the Ministry of Science and Technology of China (No.2003CB615700)
文摘Porous cordierite ceramics were prepared from a mixture of coal fly ash and basic magnesium carbonate at 1100-1350℃. Porosity,flexural strength and thermal expansion coefficient of the samples sintered at 1300℃ were estimated to be 26%,65 MPa and 4.21×10-6/ ℃ ,respectively. The kinetics of the formation progress was investigated by stepwise isothermal dilatometry (SID) accompanied with XRD,SEM and porosity measurement. It was found that the isothermal shrinkage data from SID could be well analyzed to get kinetic parameters according to the em-pirical rate equation developed by Makipirtti-Meng,dY/dt=nk(T)Y(1-Y)(Y/1-Y)1/n,where Y is the fractional shrinkage during the sintering process and n is a dimensionless component. The apparent activation energy △E values for 900-1000℃ and 1050-1150℃ were 1294 and 1778 kJ/mol,respectively.
基金Funded by the National Natural Science Foundation of China(No.51401053)the China Postdoctoral Science Foundation(No.2015T80676)+1 种基金the Natural Science Foundation of Fujian Province(No.2014J05053)the Postdoctoral Scientific Research Foundation of Fuzhou University(No.0180-601017)
文摘The non-isothermal and isothermal crystallization kinetics of Zr_（72.5）Al_（10）Fe_（17.5） glassy alloy was investigated using differential scanning calorimeter（DSC）.Under non-isothermal heating condition,the primary phase in the initial crystallization is Zr_6Al_2Fe phase and the final crystallized products consist of Zr_6Al_2Fe,Zr_2Fe and a-Zr phases.The apparent activation energy for crystallization estimated using the Kissinger method is 342.1 ±8.1 kJ/mol.The local activation energy decreased with the increase in the crystallization volume fraction during nonisothermal crystallization.Under isothermal heating condition,the average Avrami exponent of about 2.76 implies a mainly diffusion-controlled three-dimensional growth with an increasing nucleation rate.The local activation energy for isothermal crystallization shows a different variation trend from that for nonisothermal crystallization,indicating different nucleation-and-growth mechanisms for the two crystallizaiton conditions.
基金supported by the National Natural Science Foundation of China(No.52273187)National Key R&D Program of China(2021YFA1500800)+1 种基金Guangdong Basic and Applied Basic Research Foundation(2022A1515110372,2023A1515011306,2023A1515240077)Guangdong-Hong Kong Joint Laboratory for Preparation and Application of Ordered Structural Materials of Guangdong Province(2023B1212120011)。
文摘Copper complexes inspired by O_(2)-activating enzymes have been widely investigated as molecular water oxidation catalysts,capable of facile and reversible O─O bond formation and cleavage under mild conditions.In this study,two copper phenanthroline complexes,namely,Cu(phen)and Cu(dophen),exhibit high turnover frequencies(TOFs)of 74±13 and(5.66±0.29)×10^(3)s^(−1)for water oxidation,respectively.Moreover,amino acid-functionalized carbon dots(CDs)were used to support the adhesion of the[Cu]complexes onto the electrode,significantly enhancing the TOFs of(2.80±0.12)×10^(3)and(4.11±0.24)×10^(4)s^(−1),respectively,exceeding the activity of photosystem II in nature.Remarkably,the amino acid-functionalized CDs provide a secondary sphere that mimics the catalytic microenvironment of the copper centre,which promotes proton-coupled electron transfer and O─O bond formation.Finally,the photovoltaic-electrolysis(PVE)system was established using CDs-supported Cu catalysts and commercial silicon solar panels,achieving a high solar-to-hydrogen efficiency of 11.59%under the illumination of AM 1.5 G.This represents the most efficient solar-driven water splitting system based on copper-based catalysts to date,introducing the biomimetic secondary sphere to a“proton-rocking”process for water oxidation catalysis and application of the PVE system.
文摘Several nano material and reaction systems were in situ monitored with an electrochemical TEM wet cell set up. In a 1 g/L sliver particle aqueous solution, the particles were observed to be ca. 10 nm sized, in both discrete particle and nano cluster forms. The silver particles were attached to the 50 nm-thick Si3N4 windows of the wet cell and could not move freely in the liquid. With a SIC14 liquid loaded in the wet cell, silicon nano materials were controllably grown on the wet cell windows by means of a liquid phase electron beam induced deposition （EBID） method. The deposited nano dots were nicely round-shaped, and demonstrated a power law growth dependency on beam exposure time in a log-log plot. In a NiCI2 solution/Ni system, both electrochemical deposition and dissolution of the nickel nano films were observed while applying electric biases on to the nickel electrodes in the wet cell. Instead of extensional growth on existing crystals, interestingly, it is more commonly observed that new nickel nano particles grow out in front of the existing film first and then merged into the film. The wet cell set up is demonstrated to be a versatile tool for nano liquid system research.
文摘We present a facile and controllable method for the large-scale fabrication of highly-ordered octahedral Fe3O4 colloidal ＂single crystals＂ without the assistance of a substrate. Oleic acid is used to reduce the solubility of the nano-building blocks in colloidal solution and to induce a ＂crystallization＂ process. Our colloidal crystals are of multimicron size and show typical crystallographic characteristics. They have a very robust structure and can serve as a novel ordered magnetic mesoporous material with a relatively narrow pore size distribution. The sample possesses an extremely high Verwey transition temperature （Tv） of 100 K and a high saturation magnetization （Ms） of 86 emu/g at 5 K based on its good crystallinity, as well as the interparticle dipolar interaction behavior arising from its unique structure. Electrochemical measurements have demonstrated the excellent capacity of the mesoporous colloidal crystals when used in lithium-ion batteries.
