Phosphate removal from aqueous waste streams is an important approach to control the eutrophication downstream bodies of water. A Fe（Ⅲ） coordinated amino-functionalized silicate adsorbent for phosphate adsorption w...Phosphate removal from aqueous waste streams is an important approach to control the eutrophication downstream bodies of water. A Fe（Ⅲ） coordinated amino-functionalized silicate adsorbent for phosphate adsorption was synthesized by a post-grafting and metal cation incorporation process. The surface structure of the adsorbent was characterized by X-ray diffraction, N2 adsoropion/desoprotion technique, and Fourier transform infrared spectroscopy. The experimental results showed that the adsorption equilibrium data were well fitted to the Langmuir equation. The maximum adsorption capacity of the modified silicate material was 51.8 mg/g. The kinetic data from the adsorption of phosphate were fitted to pseudo second-order model. The phosphate adsorption was highly pH dependent and the relatively high removal of phosphate fell within the pH range 3.0-6.0. The coexistence of other anions in solutions has an adverse effect on phosphate adsorption; a decrease in adsorption capacity followed the order of exogenous anions： F^- 〉 SO4^2- 〉 NO3^- 〉 Cl^-. In addition, the adsorbed phosphate could be desorbed by NaOH solutions. This silicate adsorbent with a large adsorption capacity and relatively high selectivity could be utilized for the removal of phosphate from aqueous waste streams or in aquatic environment.展开更多
Fe-N/C is a promising oxygen reduction reaction(ORR)catalyst to substitute the current widely used precious metal platinum.Cost-effectively fabricating the Fe-N/C material with high catalytic activity and getting in-d...Fe-N/C is a promising oxygen reduction reaction(ORR)catalyst to substitute the current widely used precious metal platinum.Cost-effectively fabricating the Fe-N/C material with high catalytic activity and getting in-depth insight into the responsible catalytic site are of great significance.In this work,we proposed to use biomass,tea leaves waste,as the precursor to prepare ORR catalyst.By adding 5%FeCl3(wt%)into tea precursor,the pyrolysis product(i.e.,5%Fe-N/C)exhibited an excellent four-electron ORR activity,whose onset potential was only 10 m V lower than that of commercial Pt/C.The limiting current density of 5%Fe-N/C(5.75 m A/cm^(2))was even higher than Pt/C(5.44 m A/cm^(2)).Compared with other biomass or metal organic frameworks derived catalysts,5%Fe-N/C showed similar ORR activity.Also,both the methanol tolerance and material stability performances of as-prepared 5%Fe-N/C catalyst were superior to that of Pt/C.X-ray adsorption fine structure characterization revealed that the FeN4O2might be the possible catalytic site.An appropriate amount of iron chloride addition not only facilitated catalytic site formation,but also enhanced material conductivity and reaction kinetics.The results of this work may be useful for the Fe based transition metal ORR catalyst design and application.展开更多
Synthesizing polynitrogen compounds that remain stable at ambient conditions is particularly challenging because species beyond the N≡N triple bond are inherently unstable.In this study,we combine first-principles ca...Synthesizing polynitrogen compounds that remain stable at ambient conditions is particularly challenging because species beyond the N≡N triple bond are inherently unstable.In this study,we combine first-principles calculations with a machine-learning potential(MLP)to investigate the ambient stability of planar cyclo-N_(4) units embedded in a two-dimensional t-FeN_(4) monolayer.Our results show that strong Fe–N coordination inhibits N≡N reformation,enabling the square cyclo-N_(4) motif to remain dynamically stable and covalently bonded without high-pressure synthesis.Furthermore,this structure exhibits tunable magnetic anisotropy and a Néel temperature above 600 K,indicating potential for room-temperature spintronic applications.The MLP also enables the simulation of systems comprising over 100,000 atoms,including periodic sheets,nanoribbons,nanomatrices and nanosheets,revealing their structural integrity under thermal fluctuations.These results demonstrate that two-dimensional confinement provides a promising route to stabilize exotic nitrogen topologies,linking quantum-mechanical accuracy with mesoscale modelling for future spinbased technologies.展开更多
An oxygen reduction reaction(ORR)catalyst is a crucial component of metal–air batteries.Herein,modified carbon nanotubes are used to support iron phthalocyanine,followed by the fabrication of single-atom and cluster ...An oxygen reduction reaction(ORR)catalyst is a crucial component of metal–air batteries.Herein,modified carbon nanotubes are used to support iron phthalocyanine,followed by the fabrication of single-atom and cluster coexisting catalysts by the fast microwave method.The two catalysts have Fe–N_(5)and Fe–P–N_(4)coordination structures,respectively.Electrochemical tests show that the FeNC/Fe–N_(5)–C and FeNC/Fe–P–N_(4)–C catalysts have half-wave potentials of 0.906 and 0.886 V in an alkaline solvent,respectively.The Zn–air battery prepared with the FeNC/Fe–N_(5)–C catalyst has a specific capacity of 791 mA h g^(−1)and a maximum power density of 190 mW cm^(−2).DFT calculations show that the axial coordination bonds in FeNC/Fe–N_(5)–C and FeNC/Fe–P–N_(4)–C are conducive to the acceleration of the transfer of electrons.The d-band centers of the axial coordination Fe–N_(5)and Fe–P–N_(4)are closer to the Fermi level,confirming that the presence of the axial coordination bonds enhances the adsorption of the reaction intermediates and reduces the ORR barriers.展开更多
The synthesis of heterotrimetallic molecular cages is reported.The assemblies contain three types of coordination compounds:Fe^(Ⅱ)clathrochelate complexes,Au_(3)^(Ⅰ)(pyrazolate)3 complexes,and[Pd^(Ⅱ)(pyridine)_(4)]...The synthesis of heterotrimetallic molecular cages is reported.The assemblies contain three types of coordination compounds:Fe^(Ⅱ)clathrochelate complexes,Au_(3)^(Ⅰ)(pyrazolate)3 complexes,and[Pd^(Ⅱ)(pyridine)_(4)]^(2+)complexes.The cages were obtained in a stepwise fashion.A nanometer-sized metalloligand with three terminal 3-pyridyl donor groups was prepared by connection of three Fe^(Ⅱ)clathrochelate complexes via a central Au_(3)(pyrazolate)3 complex.A related strategy was employed for the synthesis of a ditopic N-donor ligand with two functionalized Fe^(Ⅱ)clathrochelate complexes.Combining the tritopic ligand with[Pd(CH_(3)CN)_(4)](BF_(4))_(2)resulted in the clean formation of a spherical Pd_(6)^(Ⅱ)Fe_(24)^(Ⅱ)Au_(24)^(Ⅰ)coordination cage with a diameter of∼4.1 nm and a molecular weight of 21 kDa.The ditopic metalloligand was used for the construction of a Pd_(2)^(Ⅱ)Pd_(8)^(Ⅱ)Au_(12)^(Ⅰ)cage.展开更多
Sophisticated aggregation assembly is challenging in assembly chemistry.Monitoring the assembly process helps to understand the assembly mechanism and create new building blocks.A two-dimensional(2D)cluster-based coor...Sophisticated aggregation assembly is challenging in assembly chemistry.Monitoring the assembly process helps to understand the assembly mechanism and create new building blocks.A two-dimensional(2D)cluster-based coordination polymer(CP)of{Fe_(5)}-2D was developed by hierarchical dimension augmentation from its one-dimensional(1D)cluster-based CP of{Fe_(5)}-1D and discrete zero-dimensional(0D)cluster of{Fe_(5)}-0D.A stepwise formation of the{Fe_(5)}-0D cluster could be further monitored by time-dependent high-resolution electrospray ionization mass spectrometry and five reaction intermediate fragments were screened.A possible bottom-up synthesis mechanism for this cluster-based CP was proposed as[Fe_(1)]→[Fe_(2)]→[Fe_(3)]→[Fe_(4)]→{Fe_(5)}-0D→{Fe_(5)}-1D→{Fe_(5)}-2D.展开更多
A new 1D coordination polymer,[Fe_(3)(μ_(2)-bntrz)_(6)(bntrz)_(2)(μ_(2)-tcnsme)_(2)](tcnsme)_(4)·4H_(2)O(1·4H_(2)O),based on[Fe_(3)(μ_(2)-bntrz)_(6)]trinuclear units covalently linked by symmetric double ...A new 1D coordination polymer,[Fe_(3)(μ_(2)-bntrz)_(6)(bntrz)_(2)(μ_(2)-tcnsme)_(2)](tcnsme)_(4)·4H_(2)O(1·4H_(2)O),based on[Fe_(3)(μ_(2)-bntrz)_(6)]trinuclear units covalently linked by symmetric double cyanocarbanion coligands involving 12-membered metallacycles has been prepared and characterised.The crystal structure of 1·4H_(2)O revealed a trinuclear fragment,[Fe_(3)(μ_(2)-bntrz)_(6)(bntrz)_(2)(μ_(2)-tcnsme)_(2)]^(4+),composed of a central Fe^(Ⅱ)ion(Fe1)and two external metal ions(Fe2),similar to that described for the discrete trinuclear complex[Fe_(3)(μ_(2)-bntrz)_(6)(tcnset)_(6)](2)previously reported.Magnetic studies of 1·4H_(2)O showed a continuous gradual decrease of the magnetic signal,characteristic of the presence of a complete one-step gradual HS to LS transition(T_(1/2)=281 K)different from the abrupt one described for 2.This difference has been attributed to the presence of competing ferro-and anti-ferroelastic interactions,induced,respectively,by the intra-(μ_(2)-bntrz)and inter-trimer(μ_(2)-tcnsme)covalent links in 1·4H_(2)O.TGA and powder X-ray diffraction analyses revealed that 1·4H_(2)O shows a complete and reversible“dehydration(1)/hydration(1·4H_(2)O)”process that occurs,respectively,by heating 1·4H_(2)O at 370 K and by soaking in water the dehydrated sample(1).The magnetic behaviour of 1 exhibits a two-step SCO transition at ca.245 K.Thanks to the combined magnetic and vibrational infrared data allowing correct extraction of the contribution of the two Fe^(Ⅱ)active centres(one central Fe1 and two external Fe2 ions),the first step(370-245 K)was attributed to a concomitant HS/LS switching of the central Fe1 and a half of the Fe2 ions and the second one,occurring below 245 K,was attributed to the HS/LS transition of the remaining HS state among the randomly distributed Fe2 external ions.Photomagnetic experiments have been performed for both hydrated(1·4H_(2)O)and dehydrated(1)phases.As expected from their thermal transition temperatures,no photomagnetic response was observed for 1·4H_(2)O at 638 nm nor at 450 nm,while the dehydrated phase(1)shows an increase of the magnetic moment,reaching a maximum of 1.4 cm^(3)K mol^(−1)at 22 K,followed by the thermallyinduced HS to LS relaxation with TLIESST=41 K.展开更多
In this study,a pair of cyanide-bridged{Fe_(2)Co}-based coordination polymers,{[(^(Pz)Tp)Fe(CN)_(3)]_(2)Co(L)_(2)}·_(4)H_(2)O(1)and{[(Tp)Fe(CN)_(3)]_(2)Co(L)_(2)}·_(3)H_(2)O·CH_(3)OH(2),was synthesized ...In this study,a pair of cyanide-bridged{Fe_(2)Co}-based coordination polymers,{[(^(Pz)Tp)Fe(CN)_(3)]_(2)Co(L)_(2)}·_(4)H_(2)O(1)and{[(Tp)Fe(CN)_(3)]_(2)Co(L)_(2)}·_(3)H_(2)O·CH_(3)OH(2),was synthesized by assembling Co^(Ⅱ) with[(^(Pz)Tp)Fe^(Ⅲ)(CN)_(3)]^(-)(^(Pz)Tp:tetrakis(pyrazolyl)borate)and the less hindered[(Tp)Fe^(Ⅲ)(CN)_(3)]-(Tp:tris(pyrazolyl)borate)in the presence of the asymmetric ditopic ligand L(4-(1H-imidazol-5-ylmethylene-amino)-4H-1,2,4-triazole).展开更多
基金supported by the National Major Research Plan for Water Pollution Control and Treatment of China(No. 2009ZX07101-015,2009ZX07105-003)
文摘Phosphate removal from aqueous waste streams is an important approach to control the eutrophication downstream bodies of water. A Fe（Ⅲ） coordinated amino-functionalized silicate adsorbent for phosphate adsorption was synthesized by a post-grafting and metal cation incorporation process. The surface structure of the adsorbent was characterized by X-ray diffraction, N2 adsoropion/desoprotion technique, and Fourier transform infrared spectroscopy. The experimental results showed that the adsorption equilibrium data were well fitted to the Langmuir equation. The maximum adsorption capacity of the modified silicate material was 51.8 mg/g. The kinetic data from the adsorption of phosphate were fitted to pseudo second-order model. The phosphate adsorption was highly pH dependent and the relatively high removal of phosphate fell within the pH range 3.0-6.0. The coexistence of other anions in solutions has an adverse effect on phosphate adsorption; a decrease in adsorption capacity followed the order of exogenous anions： F^- 〉 SO4^2- 〉 NO3^- 〉 Cl^-. In addition, the adsorbed phosphate could be desorbed by NaOH solutions. This silicate adsorbent with a large adsorption capacity and relatively high selectivity could be utilized for the removal of phosphate from aqueous waste streams or in aquatic environment.
基金the National Natural Science Foundation of China(No.51908172)for the support of this study。
文摘Fe-N/C is a promising oxygen reduction reaction(ORR)catalyst to substitute the current widely used precious metal platinum.Cost-effectively fabricating the Fe-N/C material with high catalytic activity and getting in-depth insight into the responsible catalytic site are of great significance.In this work,we proposed to use biomass,tea leaves waste,as the precursor to prepare ORR catalyst.By adding 5%FeCl3(wt%)into tea precursor,the pyrolysis product(i.e.,5%Fe-N/C)exhibited an excellent four-electron ORR activity,whose onset potential was only 10 m V lower than that of commercial Pt/C.The limiting current density of 5%Fe-N/C(5.75 m A/cm^(2))was even higher than Pt/C(5.44 m A/cm^(2)).Compared with other biomass or metal organic frameworks derived catalysts,5%Fe-N/C showed similar ORR activity.Also,both the methanol tolerance and material stability performances of as-prepared 5%Fe-N/C catalyst were superior to that of Pt/C.X-ray adsorption fine structure characterization revealed that the FeN4O2might be the possible catalytic site.An appropriate amount of iron chloride addition not only facilitated catalytic site formation,but also enhanced material conductivity and reaction kinetics.The results of this work may be useful for the Fe based transition metal ORR catalyst design and application.
基金support from Chongqing Jiaotong University (No. F1240018)Chongqing Graduate Tutor Team Construction Project (JDDSTD2022006)+1 种基金P.L. would like to thank the support from the Hunan Provincial Natural Science Foundation of China (2023JJ40621)Computing resources were provided by the National Supercomputer Centre (TianHe-3K) in Tianjin. The work also partially supported by e-INFRA CZ (ID:90140) for providing computational resources.
文摘Synthesizing polynitrogen compounds that remain stable at ambient conditions is particularly challenging because species beyond the N≡N triple bond are inherently unstable.In this study,we combine first-principles calculations with a machine-learning potential(MLP)to investigate the ambient stability of planar cyclo-N_(4) units embedded in a two-dimensional t-FeN_(4) monolayer.Our results show that strong Fe–N coordination inhibits N≡N reformation,enabling the square cyclo-N_(4) motif to remain dynamically stable and covalently bonded without high-pressure synthesis.Furthermore,this structure exhibits tunable magnetic anisotropy and a Néel temperature above 600 K,indicating potential for room-temperature spintronic applications.The MLP also enables the simulation of systems comprising over 100,000 atoms,including periodic sheets,nanoribbons,nanomatrices and nanosheets,revealing their structural integrity under thermal fluctuations.These results demonstrate that two-dimensional confinement provides a promising route to stabilize exotic nitrogen topologies,linking quantum-mechanical accuracy with mesoscale modelling for future spinbased technologies.
基金supported by the National Natural Science Foundation of China(52362036)the Science and Technology Plan Project of Gansu Province(23JRRA691).
文摘An oxygen reduction reaction(ORR)catalyst is a crucial component of metal–air batteries.Herein,modified carbon nanotubes are used to support iron phthalocyanine,followed by the fabrication of single-atom and cluster coexisting catalysts by the fast microwave method.The two catalysts have Fe–N_(5)and Fe–P–N_(4)coordination structures,respectively.Electrochemical tests show that the FeNC/Fe–N_(5)–C and FeNC/Fe–P–N_(4)–C catalysts have half-wave potentials of 0.906 and 0.886 V in an alkaline solvent,respectively.The Zn–air battery prepared with the FeNC/Fe–N_(5)–C catalyst has a specific capacity of 791 mA h g^(−1)and a maximum power density of 190 mW cm^(−2).DFT calculations show that the axial coordination bonds in FeNC/Fe–N_(5)–C and FeNC/Fe–P–N_(4)–C are conducive to the acceleration of the transfer of electrons.The d-band centers of the axial coordination Fe–N_(5)and Fe–P–N_(4)are closer to the Fermi level,confirming that the presence of the axial coordination bonds enhances the adsorption of the reaction intermediates and reduces the ORR barriers.
基金supported by theÉcole Polytechnique Fédérale de Lausanne(EPFL).
文摘The synthesis of heterotrimetallic molecular cages is reported.The assemblies contain three types of coordination compounds:Fe^(Ⅱ)clathrochelate complexes,Au_(3)^(Ⅰ)(pyrazolate)3 complexes,and[Pd^(Ⅱ)(pyridine)_(4)]^(2+)complexes.The cages were obtained in a stepwise fashion.A nanometer-sized metalloligand with three terminal 3-pyridyl donor groups was prepared by connection of three Fe^(Ⅱ)clathrochelate complexes via a central Au_(3)(pyrazolate)3 complex.A related strategy was employed for the synthesis of a ditopic N-donor ligand with two functionalized Fe^(Ⅱ)clathrochelate complexes.Combining the tritopic ligand with[Pd(CH_(3)CN)_(4)](BF_(4))_(2)resulted in the clean formation of a spherical Pd_(6)^(Ⅱ)Fe_(24)^(Ⅱ)Au_(24)^(Ⅰ)coordination cage with a diameter of∼4.1 nm and a molecular weight of 21 kDa.The ditopic metalloligand was used for the construction of a Pd_(2)^(Ⅱ)Pd_(8)^(Ⅱ)Au_(12)^(Ⅰ)cage.
基金the National Natural Science Foundation of China(No.21861005,22075056)the Foundation of State Key Laboratory for Chemistry and Molecular Engineering of Medicinal Resources(Guangxi Normal University,CMEMR2018-C15)the Guangxi Natural Science Foundation of China(2019GXNSFAA185025,2018GXNSFBA281197).
文摘Sophisticated aggregation assembly is challenging in assembly chemistry.Monitoring the assembly process helps to understand the assembly mechanism and create new building blocks.A two-dimensional(2D)cluster-based coordination polymer(CP)of{Fe_(5)}-2D was developed by hierarchical dimension augmentation from its one-dimensional(1D)cluster-based CP of{Fe_(5)}-1D and discrete zero-dimensional(0D)cluster of{Fe_(5)}-0D.A stepwise formation of the{Fe_(5)}-0D cluster could be further monitored by time-dependent high-resolution electrospray ionization mass spectrometry and five reaction intermediate fragments were screened.A possible bottom-up synthesis mechanism for this cluster-based CP was proposed as[Fe_(1)]→[Fe_(2)]→[Fe_(3)]→[Fe_(4)]→{Fe_(5)}-0D→{Fe_(5)}-1D→{Fe_(5)}-2D.
基金funded by the French CNRS(MITI Project),Mol-CoSM ANR Project No.ANR-20-CE07-0028-01financial support from“Région de Bretagne and Universitéde Brest”financial support of the Polish National Science Centre within the Opus project no.2020/39/B/ST5/02815.
文摘A new 1D coordination polymer,[Fe_(3)(μ_(2)-bntrz)_(6)(bntrz)_(2)(μ_(2)-tcnsme)_(2)](tcnsme)_(4)·4H_(2)O(1·4H_(2)O),based on[Fe_(3)(μ_(2)-bntrz)_(6)]trinuclear units covalently linked by symmetric double cyanocarbanion coligands involving 12-membered metallacycles has been prepared and characterised.The crystal structure of 1·4H_(2)O revealed a trinuclear fragment,[Fe_(3)(μ_(2)-bntrz)_(6)(bntrz)_(2)(μ_(2)-tcnsme)_(2)]^(4+),composed of a central Fe^(Ⅱ)ion(Fe1)and two external metal ions(Fe2),similar to that described for the discrete trinuclear complex[Fe_(3)(μ_(2)-bntrz)_(6)(tcnset)_(6)](2)previously reported.Magnetic studies of 1·4H_(2)O showed a continuous gradual decrease of the magnetic signal,characteristic of the presence of a complete one-step gradual HS to LS transition(T_(1/2)=281 K)different from the abrupt one described for 2.This difference has been attributed to the presence of competing ferro-and anti-ferroelastic interactions,induced,respectively,by the intra-(μ_(2)-bntrz)and inter-trimer(μ_(2)-tcnsme)covalent links in 1·4H_(2)O.TGA and powder X-ray diffraction analyses revealed that 1·4H_(2)O shows a complete and reversible“dehydration(1)/hydration(1·4H_(2)O)”process that occurs,respectively,by heating 1·4H_(2)O at 370 K and by soaking in water the dehydrated sample(1).The magnetic behaviour of 1 exhibits a two-step SCO transition at ca.245 K.Thanks to the combined magnetic and vibrational infrared data allowing correct extraction of the contribution of the two Fe^(Ⅱ)active centres(one central Fe1 and two external Fe2 ions),the first step(370-245 K)was attributed to a concomitant HS/LS switching of the central Fe1 and a half of the Fe2 ions and the second one,occurring below 245 K,was attributed to the HS/LS transition of the remaining HS state among the randomly distributed Fe2 external ions.Photomagnetic experiments have been performed for both hydrated(1·4H_(2)O)and dehydrated(1)phases.As expected from their thermal transition temperatures,no photomagnetic response was observed for 1·4H_(2)O at 638 nm nor at 450 nm,while the dehydrated phase(1)shows an increase of the magnetic moment,reaching a maximum of 1.4 cm^(3)K mol^(−1)at 22 K,followed by the thermallyinduced HS to LS relaxation with TLIESST=41 K.
基金supported by the National Natural Science Foundation of China(grants 22222103,22173015,22025101,21901133 and 21871039)the Fundamental Research Funds for the Central Universities,China。
文摘In this study,a pair of cyanide-bridged{Fe_(2)Co}-based coordination polymers,{[(^(Pz)Tp)Fe(CN)_(3)]_(2)Co(L)_(2)}·_(4)H_(2)O(1)and{[(Tp)Fe(CN)_(3)]_(2)Co(L)_(2)}·_(3)H_(2)O·CH_(3)OH(2),was synthesized by assembling Co^(Ⅱ) with[(^(Pz)Tp)Fe^(Ⅲ)(CN)_(3)]^(-)(^(Pz)Tp:tetrakis(pyrazolyl)borate)and the less hindered[(Tp)Fe^(Ⅲ)(CN)_(3)]-(Tp:tris(pyrazolyl)borate)in the presence of the asymmetric ditopic ligand L(4-(1H-imidazol-5-ylmethylene-amino)-4H-1,2,4-triazole).
