The novel Metal-Organic Frameworks(MOFs)M(BPZNH_(2))(M=Zn,Ni,Cu)were prepared from the reaction of the corresponding metal acetates M(OAc)_(2)·nH_(2)O and the organic linker 3-amino-4,4’-bipyrazole(H_(2)BPZNH_(2...The novel Metal-Organic Frameworks(MOFs)M(BPZNH_(2))(M=Zn,Ni,Cu)were prepared from the reaction of the corresponding metal acetates M(OAc)_(2)·nH_(2)O and the organic linker 3-amino-4,4’-bipyrazole(H_(2)BPZNH_(2))under solvothermal conditions.H_(2)BPZNH_(2) was obtained straightforwardly from the reduction of the related nitro-compound using hydrazine as a reducing agent.The Zn(II)polymer is characterized by a 3D porous network featuring tetrahedral metallic nodes and bridging BPZNH_(2)^(2-)anions defining the vertices and edges of square channels.The isostructural Ni(II)and Cu(II)MOFs show square-planar metallic nodes and bridging BPZNH_(2)^(2-)spacers at the vertices and edges of the rhombic channels of a 3D porous framework.All the MOFs were characterized in the solid state[(VT)-PXRD,IR,TGA-DTG].The textural property analysis revealed that they are micro-mesoporous materials with BET specific surface areas(SSAs)falling in the 100-400 m^(2) g^(-1) range.Zn(BPZNH_(2)),showing the highest SSA(395 m^(2) g^(-1))and a prevalently microporous texture(micropore area=69%of the accessible SSA),has been exploited as a CO_(2) capture material:at T=298 K and pCO_(2)=1 bar,the total gas uptake equals 3.07 mmol g^(-1)(13.5 wt%CO_(2)).Its affinity for CO_(2)(isosteric heat of adsorption Qst=35.6 kJ mol^(-1);CO_(2)/N_(2) Henry selectivity=17;CO_(2)/N_(2) IAST selectivity=14)is higher than that of its nitrofunctionalized analogue and comparable to that of other amino-decorated MOFs from the literature.Finally,Zn(BPZNH_(2))was tested as a heterogeneous catalyst in the reaction of CO_(2) with activated epoxides bearing a-CH_(2)X pendant arm(X=Cl:epichlorohydrin;X=Br:epibromohydrin)to give the corresponding cyclic carbonates at T=393 K and pCO_(2)=1 bar under green(solvent-and co-catalyst-free)conditions.A good conversion of 47%and a TOF of 3.9 mmol(carbonate)(mmolZn)^(-1) h^(-1) were recorded with epibromohydrin.展开更多
Hollow spherical lithium iron phosphate(LiFePO_(4))materials display outstanding electrochemical performance in general.Previous reports on hollow spherical LiFePO_(4)(LFP)mostly focus on electrochemical performance,w...Hollow spherical lithium iron phosphate(LiFePO_(4))materials display outstanding electrochemical performance in general.Previous reports on hollow spherical LiFePO_(4)(LFP)mostly focus on electrochemical performance,while the shape evolution process of spherical LFP particles is not clearly investigated.Therefore,in our work a simple solid-state method was applied to synthesize porous hollow spherical LFP with ammonium polyphosphate(APP)as a spheroidizing agent.The as-prepared LiFePO_(4)forms a“micro-nano”structure,which is in the form of nano-LFP particles interspersed in a micro-hollow-spherical carbon shell,delivering a specific capacity of 163 mA h g^(-1) at 0.1 C and 123 mA h g^(-1) at 10 C.More importantly,we clarified the spheroidization process of spherical LFP particles in our work through a series of characterization studies.It is found that APP and the carbon source play critical roles in the shape evolution process at respective temperature regions.Among them,the cohesive behavior of the APP chain results in surface tension and drives the spheroidization process at low temperatures.The carbon source around the LFP particles confines mass transfer and maintains the hollow spherical structure at high temperatures.The exploration of the spheroidization mechanism is instructive for the use of long-chain precursors to synthesize materials with porous-hollow-spherical morphology via a simple process.展开更多
The emerging application of crystalline red phosphorus(RP)in optoelectronics such as photocatalysis is bogged down by its limited synthesis routes.Scalable and controllable solution phase methods usually lead to the f...The emerging application of crystalline red phosphorus(RP)in optoelectronics such as photocatalysis is bogged down by its limited synthesis routes.Scalable and controllable solution phase methods usually lead to the formation of amorphous RP products.Herein,we developed a facile and mild solvothermal strategy to synthesize highly crystalline RP by selecting 1,2-diaminopropane as an appropriate nucleophilic agent.The diamine-induced“dissolution–crystallization”mechanism was proposed to explain the phosphorus phase transition in solution from amorphous RP,via polyphosphide anions,to crystalline RP.The structure of this crystalline RP was assigned to Form II RP by X-ray diffraction pattern matching and other morphological characterization methods.This novel method to prepare Form II RP may offer a chance for its potential photocatalytic water splitting and the solution phase fabrication of other elemental phosphorus allotropes.展开更多
基金the University of Camerino and the Italian MIUR throughout the PRIN 2015 Project Towards a Sustainable Chemistry(20154X9ATP_002).
文摘The novel Metal-Organic Frameworks(MOFs)M(BPZNH_(2))(M=Zn,Ni,Cu)were prepared from the reaction of the corresponding metal acetates M(OAc)_(2)·nH_(2)O and the organic linker 3-amino-4,4’-bipyrazole(H_(2)BPZNH_(2))under solvothermal conditions.H_(2)BPZNH_(2) was obtained straightforwardly from the reduction of the related nitro-compound using hydrazine as a reducing agent.The Zn(II)polymer is characterized by a 3D porous network featuring tetrahedral metallic nodes and bridging BPZNH_(2)^(2-)anions defining the vertices and edges of square channels.The isostructural Ni(II)and Cu(II)MOFs show square-planar metallic nodes and bridging BPZNH_(2)^(2-)spacers at the vertices and edges of the rhombic channels of a 3D porous framework.All the MOFs were characterized in the solid state[(VT)-PXRD,IR,TGA-DTG].The textural property analysis revealed that they are micro-mesoporous materials with BET specific surface areas(SSAs)falling in the 100-400 m^(2) g^(-1) range.Zn(BPZNH_(2)),showing the highest SSA(395 m^(2) g^(-1))and a prevalently microporous texture(micropore area=69%of the accessible SSA),has been exploited as a CO_(2) capture material:at T=298 K and pCO_(2)=1 bar,the total gas uptake equals 3.07 mmol g^(-1)(13.5 wt%CO_(2)).Its affinity for CO_(2)(isosteric heat of adsorption Qst=35.6 kJ mol^(-1);CO_(2)/N_(2) Henry selectivity=17;CO_(2)/N_(2) IAST selectivity=14)is higher than that of its nitrofunctionalized analogue and comparable to that of other amino-decorated MOFs from the literature.Finally,Zn(BPZNH_(2))was tested as a heterogeneous catalyst in the reaction of CO_(2) with activated epoxides bearing a-CH_(2)X pendant arm(X=Cl:epichlorohydrin;X=Br:epibromohydrin)to give the corresponding cyclic carbonates at T=393 K and pCO_(2)=1 bar under green(solvent-and co-catalyst-free)conditions.A good conversion of 47%and a TOF of 3.9 mmol(carbonate)(mmolZn)^(-1) h^(-1) were recorded with epibromohydrin.
基金supported by the National Natural Science Foundation of China(No.81927809 and 21777108)the Science and Technology Department of Sichuan Province(No.2019YFG0218)。
文摘Hollow spherical lithium iron phosphate(LiFePO_(4))materials display outstanding electrochemical performance in general.Previous reports on hollow spherical LiFePO_(4)(LFP)mostly focus on electrochemical performance,while the shape evolution process of spherical LFP particles is not clearly investigated.Therefore,in our work a simple solid-state method was applied to synthesize porous hollow spherical LFP with ammonium polyphosphate(APP)as a spheroidizing agent.The as-prepared LiFePO_(4)forms a“micro-nano”structure,which is in the form of nano-LFP particles interspersed in a micro-hollow-spherical carbon shell,delivering a specific capacity of 163 mA h g^(-1) at 0.1 C and 123 mA h g^(-1) at 10 C.More importantly,we clarified the spheroidization process of spherical LFP particles in our work through a series of characterization studies.It is found that APP and the carbon source play critical roles in the shape evolution process at respective temperature regions.Among them,the cohesive behavior of the APP chain results in surface tension and drives the spheroidization process at low temperatures.The carbon source around the LFP particles confines mass transfer and maintains the hollow spherical structure at high temperatures.The exploration of the spheroidization mechanism is instructive for the use of long-chain precursors to synthesize materials with porous-hollow-spherical morphology via a simple process.
基金funded by the National Natural Science Foundation of China(No.21671115 and 52072198)the Science Challenge Project(TZ2018004)the Tsinghua University Initiative Scientific Research Program(2018Z05JZY022).We are also grateful to Dr Haifang Li for her assistance in ESI-MS characterization.
文摘The emerging application of crystalline red phosphorus(RP)in optoelectronics such as photocatalysis is bogged down by its limited synthesis routes.Scalable and controllable solution phase methods usually lead to the formation of amorphous RP products.Herein,we developed a facile and mild solvothermal strategy to synthesize highly crystalline RP by selecting 1,2-diaminopropane as an appropriate nucleophilic agent.The diamine-induced“dissolution–crystallization”mechanism was proposed to explain the phosphorus phase transition in solution from amorphous RP,via polyphosphide anions,to crystalline RP.The structure of this crystalline RP was assigned to Form II RP by X-ray diffraction pattern matching and other morphological characterization methods.This novel method to prepare Form II RP may offer a chance for its potential photocatalytic water splitting and the solution phase fabrication of other elemental phosphorus allotropes.
