The hydrogen absorption/desorption kinetic properties of MgH_(2)can be effectively enhanced by doping specific catalysts.In this work,MOFs-derived NiCu@C nanoparticles(~15 nm)with regular core-shell structure were suc...The hydrogen absorption/desorption kinetic properties of MgH_(2)can be effectively enhanced by doping specific catalysts.In this work,MOFs-derived NiCu@C nanoparticles(~15 nm)with regular core-shell structure were successfully prepared and introduced into MgH_(2)(denoted as MgH_(2)-NiCu@C).The onset and peak temperatures of hydrogen desorption of MgH_(2)-11 wt.%NiCu@C are 175.0℃and282.2℃,respectively.The apparent activation energy of dehydrogenated reaction is 77.2±4.5 kJ/mol for MgH_(2)-11 wt.%NiCu@C,which is lower than half of that of the as-milled MgH_(2).Moreover,MgH_(2)-11 wt.%NiCu@C displays great cyclic stability.The strengthening"hydrogen pumping"effect of reversible solid solutions Mg_(2)Ni(Cu)/Mg_(2)Ni(Cu)H_(4)is proposed to explain the remarkable improvement in hydrogen absorption/desorption kinetic properties of MgH_(2).This work offers a novel perspective for the design of bimetallic nanoparticles and beyond for application in hydrogen storage and other energy related fields.展开更多
The electrochemical properties of the super-stoichiometric TiV-based hydrogen storage electrode alloys(Ti 0.8Zr 0.2)(V 0.533Mn 0.107Cr 0.16Ni 0.2) x(x=2, 3, 4, 5, 6) were studied. It is found by XRD analysis that all ...The electrochemical properties of the super-stoichiometric TiV-based hydrogen storage electrode alloys(Ti 0.8Zr 0.2)(V 0.533Mn 0.107Cr 0.16Ni 0.2) x(x=2, 3, 4, 5, 6) were studied. It is found by XRD analysis that all the alloys mainly consist of a C14 Laves phase with hexagonal structure and a V-based solid solution phase with BCC structure. The lattice parameters and the unit cell volumes of the two phases decrease with increasing x. The cycle life, the linear polarization, the anode polarization and the electrochemical impedance spectra of the alloy electrodes were investigated systematically. The overall electrochemical properties of the alloy electrode are found improved greatly as the result of super-stoichiometry and get to the best when x=5.展开更多
Mg-based metal hydrides are promising as hydrogen storage materials for fuel ce ll application. In this work,Mg2FeH6 complex hydride phase was synthesized by controlled reactive ball milling of 2Mg-Fe （atomic ratio）...Mg-based metal hydrides are promising as hydrogen storage materials for fuel ce ll application. In this work,Mg2FeH6 complex hydride phase was synthesized by controlled reactive ball milling of 2Mg-Fe （atomic ratio） powder mixture in H2. Mg2FeH6 is confirmed to be formed via the following three stages: form ation of MgH2 via the reaction of Mg with H2,incubation stage and formation of Mg2FeH6 by reaction of fully refined MgH2 and Fe. The incubation stage is characterized by no traces of Mg or hydride crystalline phase by XRD. On the other hand,Mg is observed uniformly distributed in the milled powder by SEM-E DS. Also,almost the same amount of H2 as the first stage is detected stored i n the powders of the second stage by DSC and TGA.展开更多
The La 1- x Ce x (NiCoMnAl) 5 alloy electrodes were treated by hot charging in alkaline aqueous solution containing KBH 4. The activation behavior, hydrogen diffusion coefficient and maximum discharging capacity, high...The La 1- x Ce x (NiCoMnAl) 5 alloy electrodes were treated by hot charging in alkaline aqueous solution containing KBH 4. The activation behavior, hydrogen diffusion coefficient and maximum discharging capacity, high rate discharging capability of alloy electrodes were tested. The surface morphology and element content were observed by scanning electron microscope. The results show that the alloy electrode is fully activated after the second charging discharging cycle and has a high rate discharging capability of 85% at 900 mA/g. The surface has a lot of micro cracks and hydrogen diffusion coefficient is about (2～3)×10 -9 cm 2/s . Therefore, this method can markedly improve activation behavior and high rate charging capacity of the alloy electrode. The mechanism of this surface modification of the alloy electrode is also discussed. [展开更多
In order to examine the effects of structure stability on the degradation behaviors of multiphase La0.7Mg0.3Ni3 alloy,changes of the crystal structure and hydrogen storage properties after gas-solid cycling were inves...In order to examine the effects of structure stability on the degradation behaviors of multiphase La0.7Mg0.3Ni3 alloy,changes of the crystal structure and hydrogen storage properties after gas-solid cycling were investigated in detail.The structural analysis identifies that（La,Mg）Ni3（PuNi3-type） phase transforms to amorphous,i.e.,hydrogen-induced amorphization（HIA） occurs whereas LaNi5（CaCu5-type）,（La,Mg）2Ni7（Ce2Ni7-type）,and（La,Mg）5Ni19（Pr5Co19-type） phases still keep crystalline upon hydriding/dehydriding cycling.Partial amorphization remarkably affects both the gas-solid and electrochemical storage performances.The plateau of PCT curves becomes narrow and steep with cycling.Moreover,the maximum electrochemical capacity decreases notably after gas-solid hydrogenation repeats.The electrochemical capacity reduction could be ascribed to both drop of the maximum storage capacity and the slope of plateau induced by partial amorphization.For direct electrochemical cycling,it is suggested that the capacity decay is mainly attributed to HIA in the initial stage.展开更多
V48Fe12Ti15Cr25 alloy was prepared using vacuum arc melting and was subsequently annealed for 10 h at 1273 K.The effects of annealing on the hydrogen storage properties and microstructure of the V48Fe12Ti15Cr25 alloys...V48Fe12Ti15Cr25 alloy was prepared using vacuum arc melting and was subsequently annealed for 10 h at 1273 K.The effects of annealing on the hydrogen storage properties and microstructure of the V48Fe12Ti15Cr25 alloys were investigated.The results indicated that the alloy consisted of main body-centered cubic,Ti-rich,and TiFe phases.After annealing,the kinetic properties of the alloy were improved but its hydrogen storage capacity was slightly reduced.The kinetic mechanisms of the hydrogen absorption and desorption of the alloys were studied.The dehydrogenation enthalpy of the alloy was decreased by 2.57 kJ/mol after annealing.Differential scanning calorimetry indicated that the hydride decomposition temperature of the annealed alloy was decreased.The hydrogen desorption activation energies of the as-cast and annealed alloys were calculated to be 79.41 and 71.25 kJ/mol,respectively.The results illustrated that annealing was a beneficial method of improving the kinetic and thermodynamic properties of the hydrogen absorption/desorption of the alloy.展开更多
Fe^3+and Zn^2+ions were doped into the lattice of CeO2 via the hydrothermal method.The micro structure and spectra features were analyzed systemically.XRD results show that the solid solubility of Fe^3+and Zn^2+ions i...Fe^3+and Zn^2+ions were doped into the lattice of CeO2 via the hydrothermal method.The micro structure and spectra features were analyzed systemically.XRD results show that the solid solubility of Fe^3+and Zn^2+ions in Ce1-x(Fe0.5Zn0.5)xO2 can be identified as x=0.16.The cell volumes are decreased by increasing the doped content.The TEM graphs prove that the grain size of the sample is about 10 nm,and the EDS result indicates that the doped contents are in accordance with that of the theory concentrations.Meanwhile,the doping also causes the increasing concentrations of the defects and oxygen vacancies which are supported by the XPS,Raman,UV and PL characterizations.The samples exhibit better catalytic activities for improving the hydrogen storage properties and the electrochemical kinetics of the ball milled Mg2Ni based composites.Further,the catalysis effects are improved by increasing the doped contents,which can be ascribed to the increasing contents of the oxygen vacancies,defects,the special electron transition states and the nature of the doped ions in CeO2-based solid solutions.展开更多
In order to improve performance of Ti-V-based solid solution alloy, electrochemical characteristics and synergetic effect of Ti0.10Zr0.15V0.35Cr0.10Ni0.30-10 wt.%LaNi5 hydrogen storage composite electrode prepared by ...In order to improve performance of Ti-V-based solid solution alloy, electrochemical characteristics and synergetic effect of Ti0.10Zr0.15V0.35Cr0.10Ni0.30-10 wt.%LaNi5 hydrogen storage composite electrode prepared by two-step arc-melting were investigated system-atically. X-ray diffractometry （XRD） and scanning electron microscopy-energy dispersive spectroscopy （SEM-EDS） showed that the main phase of composite alloy was composed of V-based solid solution phase with a BCC structure and C14 Laves phase with hexagonal structure, while secondary phase also existed in the composite alloy. The results showed that electrochemical characteristics of the composite alloy elec-trode were significantly improved. It was suggested that synergetic effect appeared in the maximum discharge capacity of the composite alloy, synergetic effect of the discharge capacity appeared in the activation process, in the composite process, in the cyclic process, in the discharge process at low/high temperature and at different current densities, and synergetic effect existed in the charge-transfer resistance and in the ex-change current density, which seemed to be related to formation of the secondary phase.展开更多
Crystal structure and some dynamic performances of Zi0.25V0.34Dy0.01Cr0.1Ni0.3 hydrogen storage electrode alloy have been investigated by XRD, FESEM-EDS, TEM and EIS measurements. The result shows that the alloy is ma...Crystal structure and some dynamic performances of Zi0.25V0.34Dy0.01Cr0.1Ni0.3 hydrogen storage electrode alloy have been investigated by XRD, FESEM-EDS, TEM and EIS measurements. The result shows that the alloy is mainly composed of V-based solid solution phase with body-centered-cubic structure and mono-crystal Ni3Ti phase with hexagonal structure （Space grope： P63/ mmc）, and it was first observed as TiNi-based secondary phase. The higher charge transfer resistance, higher apparent activation energy and lower hydrogen diffusion coefficient are reasons for the poor electrochemical activity of the dehydriding kinetics of Ti- V-Cr-Ni hydride alloy.展开更多
基金supported by the National Natural Science Foundation of China(52071177,52171214)Postgraduate Research&Practice Innovation Program of Jiangsu Province(KYCX21_1112,KYCX21_1107)+1 种基金Six Talent Peaks Project in Jiangsu Province(2018,XNY-020)the Priority Academic Program Development(PAPD)of Jiangsu Higher Education Institutions。
文摘The hydrogen absorption/desorption kinetic properties of MgH_(2)can be effectively enhanced by doping specific catalysts.In this work,MOFs-derived NiCu@C nanoparticles(~15 nm)with regular core-shell structure were successfully prepared and introduced into MgH_(2)(denoted as MgH_(2)-NiCu@C).The onset and peak temperatures of hydrogen desorption of MgH_(2)-11 wt.%NiCu@C are 175.0℃and282.2℃,respectively.The apparent activation energy of dehydrogenated reaction is 77.2±4.5 kJ/mol for MgH_(2)-11 wt.%NiCu@C,which is lower than half of that of the as-milled MgH_(2).Moreover,MgH_(2)-11 wt.%NiCu@C displays great cyclic stability.The strengthening"hydrogen pumping"effect of reversible solid solutions Mg_(2)Ni(Cu)/Mg_(2)Ni(Cu)H_(4)is proposed to explain the remarkable improvement in hydrogen absorption/desorption kinetic properties of MgH_(2).This work offers a novel perspective for the design of bimetallic nanoparticles and beyond for application in hydrogen storage and other energy related fields.
文摘The electrochemical properties of the super-stoichiometric TiV-based hydrogen storage electrode alloys(Ti 0.8Zr 0.2)(V 0.533Mn 0.107Cr 0.16Ni 0.2) x(x=2, 3, 4, 5, 6) were studied. It is found by XRD analysis that all the alloys mainly consist of a C14 Laves phase with hexagonal structure and a V-based solid solution phase with BCC structure. The lattice parameters and the unit cell volumes of the two phases decrease with increasing x. The cycle life, the linear polarization, the anode polarization and the electrochemical impedance spectra of the alloy electrodes were investigated systematically. The overall electrochemical properties of the alloy electrode are found improved greatly as the result of super-stoichiometry and get to the best when x=5.
文摘Mg-based metal hydrides are promising as hydrogen storage materials for fuel ce ll application. In this work,Mg2FeH6 complex hydride phase was synthesized by controlled reactive ball milling of 2Mg-Fe （atomic ratio） powder mixture in H2. Mg2FeH6 is confirmed to be formed via the following three stages: form ation of MgH2 via the reaction of Mg with H2,incubation stage and formation of Mg2FeH6 by reaction of fully refined MgH2 and Fe. The incubation stage is characterized by no traces of Mg or hydride crystalline phase by XRD. On the other hand,Mg is observed uniformly distributed in the milled powder by SEM-E DS. Also,almost the same amount of H2 as the first stage is detected stored i n the powders of the second stage by DSC and TGA.
文摘The La 1- x Ce x (NiCoMnAl) 5 alloy electrodes were treated by hot charging in alkaline aqueous solution containing KBH 4. The activation behavior, hydrogen diffusion coefficient and maximum discharging capacity, high rate discharging capability of alloy electrodes were tested. The surface morphology and element content were observed by scanning electron microscope. The results show that the alloy electrode is fully activated after the second charging discharging cycle and has a high rate discharging capability of 85% at 900 mA/g. The surface has a lot of micro cracks and hydrogen diffusion coefficient is about (2～3)×10 -9 cm 2/s . Therefore, this method can markedly improve activation behavior and high rate charging capacity of the alloy electrode. The mechanism of this surface modification of the alloy electrode is also discussed. [
基金financially supported by the National Natural Science Foundation of China(Nos.51161015 and 51371094)the Application Technology Research and Development Foundation of Inner Mongolia(No.20111401)the Innovation Foundation of Inner Mongolia University of Science and Technology(No.2012NCL024)
文摘In order to examine the effects of structure stability on the degradation behaviors of multiphase La0.7Mg0.3Ni3 alloy,changes of the crystal structure and hydrogen storage properties after gas-solid cycling were investigated in detail.The structural analysis identifies that（La,Mg）Ni3（PuNi3-type） phase transforms to amorphous,i.e.,hydrogen-induced amorphization（HIA） occurs whereas LaNi5（CaCu5-type）,（La,Mg）2Ni7（Ce2Ni7-type）,and（La,Mg）5Ni19（Pr5Co19-type） phases still keep crystalline upon hydriding/dehydriding cycling.Partial amorphization remarkably affects both the gas-solid and electrochemical storage performances.The plateau of PCT curves becomes narrow and steep with cycling.Moreover,the maximum electrochemical capacity decreases notably after gas-solid hydrogenation repeats.The electrochemical capacity reduction could be ascribed to both drop of the maximum storage capacity and the slope of plateau induced by partial amorphization.For direct electrochemical cycling,it is suggested that the capacity decay is mainly attributed to HIA in the initial stage.
基金National Natural Science Foundation of China(Grant No.51901105)Natural Science Foundation of Inner Mongolia,China(Grant Nos.2018LH05010,2019BS05005,and 2017BS0507).
文摘V48Fe12Ti15Cr25 alloy was prepared using vacuum arc melting and was subsequently annealed for 10 h at 1273 K.The effects of annealing on the hydrogen storage properties and microstructure of the V48Fe12Ti15Cr25 alloys were investigated.The results indicated that the alloy consisted of main body-centered cubic,Ti-rich,and TiFe phases.After annealing,the kinetic properties of the alloy were improved but its hydrogen storage capacity was slightly reduced.The kinetic mechanisms of the hydrogen absorption and desorption of the alloys were studied.The dehydrogenation enthalpy of the alloy was decreased by 2.57 kJ/mol after annealing.Differential scanning calorimetry indicated that the hydride decomposition temperature of the annealed alloy was decreased.The hydrogen desorption activation energies of the as-cast and annealed alloys were calculated to be 79.41 and 71.25 kJ/mol,respectively.The results illustrated that annealing was a beneficial method of improving the kinetic and thermodynamic properties of the hydrogen absorption/desorption of the alloy.
基金supported by the National Natural Science Foundation of China(51962028,51501095)the Natural Science Foundation of Inner Mongolia(2017MS(LH)0516,2018MS05040,2018BS05010,2017MS(LH)0519)the Innovation Fund of Inner Mongolia University of Science and Technology(2018YQL02).
文摘Fe^3+and Zn^2+ions were doped into the lattice of CeO2 via the hydrothermal method.The micro structure and spectra features were analyzed systemically.XRD results show that the solid solubility of Fe^3+and Zn^2+ions in Ce1-x(Fe0.5Zn0.5)xO2 can be identified as x=0.16.The cell volumes are decreased by increasing the doped content.The TEM graphs prove that the grain size of the sample is about 10 nm,and the EDS result indicates that the doped contents are in accordance with that of the theory concentrations.Meanwhile,the doping also causes the increasing concentrations of the defects and oxygen vacancies which are supported by the XPS,Raman,UV and PL characterizations.The samples exhibit better catalytic activities for improving the hydrogen storage properties and the electrochemical kinetics of the ball milled Mg2Ni based composites.Further,the catalysis effects are improved by increasing the doped contents,which can be ascribed to the increasing contents of the oxygen vacancies,defects,the special electron transition states and the nature of the doped ions in CeO2-based solid solutions.
基金Project supported by the Natural Science Foundation of Hebei Province (B2011203074)
文摘In order to improve performance of Ti-V-based solid solution alloy, electrochemical characteristics and synergetic effect of Ti0.10Zr0.15V0.35Cr0.10Ni0.30-10 wt.%LaNi5 hydrogen storage composite electrode prepared by two-step arc-melting were investigated system-atically. X-ray diffractometry （XRD） and scanning electron microscopy-energy dispersive spectroscopy （SEM-EDS） showed that the main phase of composite alloy was composed of V-based solid solution phase with a BCC structure and C14 Laves phase with hexagonal structure, while secondary phase also existed in the composite alloy. The results showed that electrochemical characteristics of the composite alloy elec-trode were significantly improved. It was suggested that synergetic effect appeared in the maximum discharge capacity of the composite alloy, synergetic effect of the discharge capacity appeared in the activation process, in the composite process, in the cyclic process, in the discharge process at low/high temperature and at different current densities, and synergetic effect existed in the charge-transfer resistance and in the ex-change current density, which seemed to be related to formation of the secondary phase.
基金financially supported by the Doctoral Foundation of Yanshan University(No.B330)
文摘Crystal structure and some dynamic performances of Zi0.25V0.34Dy0.01Cr0.1Ni0.3 hydrogen storage electrode alloy have been investigated by XRD, FESEM-EDS, TEM and EIS measurements. The result shows that the alloy is mainly composed of V-based solid solution phase with body-centered-cubic structure and mono-crystal Ni3Ti phase with hexagonal structure （Space grope： P63/ mmc）, and it was first observed as TiNi-based secondary phase. The higher charge transfer resistance, higher apparent activation energy and lower hydrogen diffusion coefficient are reasons for the poor electrochemical activity of the dehydriding kinetics of Ti- V-Cr-Ni hydride alloy.
