LiAIH4 doped with Ni and Ce（SO4）2 additives and the effect of doping on temperature and hydrogen release were studied by pressure-content-temperature （PCT） experiment and X-ray diffraction （XRD） analysis. It is ...LiAIH4 doped with Ni and Ce（SO4）2 additives and the effect of doping on temperature and hydrogen release were studied by pressure-content-temperature （PCT） experiment and X-ray diffraction （XRD） analysis. It is indicated that doping with Ni induces a significant decrease in temperature in the first step and LiA1H4 doped with 1mol% Ni presents the most absorption of hydrogen. Doping with Ce（S04）2 also causes a marked decrease, while the amount of hydrogen release changes only slightly. The results from X-ray diffraction analysis show that doping does not cause any structural change; Ni and Ce-containing phases are not observed at room temoerature or even at 250℃.展开更多
TiC-doped NaA1H4 complex hydrides were prepared by hydrogenation of ball-milled Nail/A1 mixture with x TiC powder （x = 0, 5%, 8%, 10%, mole fraction）. The effects of TiC catalyst content on the absorption/desorption...TiC-doped NaA1H4 complex hydrides were prepared by hydrogenation of ball-milled Nail/A1 mixture with x TiC powder （x = 0, 5%, 8%, 10%, mole fraction）. The effects of TiC catalyst content on the absorption/desorption behaviors of the samples were investigated. The results show that TiC can improve the hydriding/dehydriding kinetics of sodium aluminum hydride, the hydriding rate of the sample increases with increasing TiC content. It is found that the TiC-doped NaA1H4 composites have a relatively good cyclic stability. The composite doped with 10% TiC maintains steadily about 4.5% （mass fraction） hydrogen absorption capacity as against about 3.8% （mass fraction） hydrogen desorption capacity over 8 cycles. The particle sizes of the TiC-doped NaA1H4 composites can be reduced to 50-100 nm, which may play an important role in improving the hydriding/dehydriding kinetics.展开更多
Owing to its favorable thermodynamics and high density,NaAlH_(4) has been widely regarded as a potential hydrogen storage material,but its practical application is hindered by the sluggish kinetics,high operating temp...Owing to its favorable thermodynamics and high density,NaAlH_(4) has been widely regarded as a potential hydrogen storage material,but its practical application is hindered by the sluggish kinetics,high operating temperature and poor cycling stability.Here,taking advantage of Co-doped nanoporous carbon scaffolds as structural host,we develop a new strategy to balance the synergistic effect between the catalytic role of Co nanoparticles and the nanoconfinement role of porous carbon scaffolds via the controllable etching of Co nanoparticles towards enhanced hydrogen storage performance of NaAlH_(4).The etching of Co nanoparticles creates extra void spaces nearby catalytically active Co nanoparticles,which not only exerts the catalytic effect of Co nanoparticles,but also improves the nanoconfinement role in maintaining the cycling stability towards increased loading ratio and hence high systematic capacity.Induced by this balanced synergistic effect,the peak temperature for the dehydrogenation of NaAlH_(4) could be reduced to 164°C,97°C lower than the bulk counterpart,even under an ultrahigh loading ratio of 67%,and more importantly,the reversible systematic hydrogen storage capacity could still reach 3.3 wt.%after 5 cycles.This work opens up a new avenue to improve the hydrogen storage performance of various complex hydrides.展开更多
For the first time,the MgH_(2)–NaAlH_(4)(ratio 4:1)destabilized system with CoTiO_(3) addition has been explored.The CoTiO_(3)-doped MgH_(2)–NaAlH_(4) sample begins to dehydrogenate at 130℃,which is declined by 40...For the first time,the MgH_(2)–NaAlH_(4)(ratio 4:1)destabilized system with CoTiO_(3) addition has been explored.The CoTiO_(3)-doped MgH_(2)–NaAlH_(4) sample begins to dehydrogenate at 130℃,which is declined by 40℃ compared to the undoped MgH_(2)–NaAlH_(4).Moreover,the de/rehydrogenation kinetics characteristics of the CoTiO_(3)-doped MgH_(2)–NaAlH_(4) were greatly ameliorated.With the inclusion of CoTiO_(3),the MgH_(2)–NaAlH_(4) composite absorbed 5.2 wt.%H_(2),higher than undoped MgH_(2)–NaAlH_(4).In the context of dehydrogenation,the CoTiO_(3)-doped MgH_(2)–NaAlH_(4) sample desorbed 2.6 wt.%H_(2),almost doubled compared to the amount of hydrogen desorbed from the undoped MgH_(2)–NaAlH_(4) sample.The activation energy obtained by the Kissinger analysis for MgH_(2) decomposition was significantly lower by 35.9 kJ/mol than the undoped MgH_(2)–NaAlH_(4) sample.The reaction mechanism demonstrated that new phases of MgCo and AlTi_(3) were generated in situ during the heating process and are likely to play a substantial catalytic function and be useful in ameliorating the de/rehydrogenation properties of the destabilized MgH_(2)–NaAlH_(4) system with the inclusion of CoTiO_(3).展开更多
The catalytic effects of ZrC powder on the dehydrogenation properties of LiAlH4 prepared by designed mixing processes were systematically investigated.The onset dehydrogenation temperatures for the 10 mol% ZrC-doped s...The catalytic effects of ZrC powder on the dehydrogenation properties of LiAlH4 prepared by designed mixing processes were systematically investigated.The onset dehydrogenation temperatures for the 10 mol% ZrC-doped sample are 85.3 and 148.4℃for the first two dehydrogenation stages,decreasing by 90.7 and 57.8℃,respectively,compared with those of the as-received LiAIH4.The isothermal volumetric measurement indicates that adding ZrC powder could significantly enhance the desorption kinetics of LiAlH4.The reaction constant and Avrami index show that the first dehydrogenation stage is controlled by diffusion mechanism with nucleation rate gradually decreasing and the second stage is a freedom nucleation and subsequent growth process.The microstructures and phase transformation characterized by scanning electron microscopy(SEM),X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS) and Fourier transform infrared spectroscopy(FTIR) reveal that the improved desorption behavior of LiAlH4 is primarily due to the high density of surface defects and embedded catalyst particles on the surface of LiAlH4 particles during the high-energy mixing process.展开更多
The Bells是一首四节不规则颂诗,连续讲述人生的不同阶段;每一节都有它自己的金属钟声:雪橇的银铃、婚礼的金钟、铜的警钟和铁的丧钟。这四种钟声分别表达了作者对每一个人生阶段的不同态度。"音必须像是义的回音",作者对音...The Bells是一首四节不规则颂诗,连续讲述人生的不同阶段;每一节都有它自己的金属钟声:雪橇的银铃、婚礼的金钟、铜的警钟和铁的丧钟。这四种钟声分别表达了作者对每一个人生阶段的不同态度。"音必须像是义的回音",作者对音素的使用成功地表达了想要表达的思想感情。展开更多
基金supported by the National High-Tech Research and Development Program (No.2006AA05Z132)the Program of the Ministry of Education of China for Changjiang Scholars and Innovative Research Teams in Universities (No.I2P407)
文摘LiAIH4 doped with Ni and Ce（SO4）2 additives and the effect of doping on temperature and hydrogen release were studied by pressure-content-temperature （PCT） experiment and X-ray diffraction （XRD） analysis. It is indicated that doping with Ni induces a significant decrease in temperature in the first step and LiA1H4 doped with 1mol% Ni presents the most absorption of hydrogen. Doping with Ce（S04）2 also causes a marked decrease, while the amount of hydrogen release changes only slightly. The results from X-ray diffraction analysis show that doping does not cause any structural change; Ni and Ce-containing phases are not observed at room temoerature or even at 250℃.
基金Project(2010CB631300)supported by the National Basic Research Program of ChinaProjects(50871099,51001090)supported by the National Natural Science Foundation of China+1 种基金Projects(20080440196,200902622)supported by the China Postdoctoral Science FoundationProject(20090101110050)supported by the University Doctoral Foundation of the Ministry of Education,China
文摘TiC-doped NaA1H4 complex hydrides were prepared by hydrogenation of ball-milled Nail/A1 mixture with x TiC powder （x = 0, 5%, 8%, 10%, mole fraction）. The effects of TiC catalyst content on the absorption/desorption behaviors of the samples were investigated. The results show that TiC can improve the hydriding/dehydriding kinetics of sodium aluminum hydride, the hydriding rate of the sample increases with increasing TiC content. It is found that the TiC-doped NaA1H4 composites have a relatively good cyclic stability. The composite doped with 10% TiC maintains steadily about 4.5% （mass fraction） hydrogen absorption capacity as against about 3.8% （mass fraction） hydrogen desorption capacity over 8 cycles. The particle sizes of the TiC-doped NaA1H4 composites can be reduced to 50-100 nm, which may play an important role in improving the hydriding/dehydriding kinetics.
基金This work was partially supported by the National Key R&D Program of China(No.2018YFB1502101)National Science Fund for Distinguished Young Scholars(51625102)+3 种基金the National Natural Science Foundation of China(51971065,51901045)the Innovation Program of Shanghai Municipal Education Commission(2019-01-07-00-07-E00028)the Open Fund of the Guangdong Provincial Key Laboratory of Advanced Energy Storage Materialsthe Programs for Professor of Special Appointment(Eastern Scholar)at Shanghai Institutions of Higher Learning。
文摘Owing to its favorable thermodynamics and high density,NaAlH_(4) has been widely regarded as a potential hydrogen storage material,but its practical application is hindered by the sluggish kinetics,high operating temperature and poor cycling stability.Here,taking advantage of Co-doped nanoporous carbon scaffolds as structural host,we develop a new strategy to balance the synergistic effect between the catalytic role of Co nanoparticles and the nanoconfinement role of porous carbon scaffolds via the controllable etching of Co nanoparticles towards enhanced hydrogen storage performance of NaAlH_(4).The etching of Co nanoparticles creates extra void spaces nearby catalytically active Co nanoparticles,which not only exerts the catalytic effect of Co nanoparticles,but also improves the nanoconfinement role in maintaining the cycling stability towards increased loading ratio and hence high systematic capacity.Induced by this balanced synergistic effect,the peak temperature for the dehydrogenation of NaAlH_(4) could be reduced to 164°C,97°C lower than the bulk counterpart,even under an ultrahigh loading ratio of 67%,and more importantly,the reversible systematic hydrogen storage capacity could still reach 3.3 wt.%after 5 cycles.This work opens up a new avenue to improve the hydrogen storage performance of various complex hydrides.
基金supported by the Research Intensified Grant Scheme (RIGS) under grant number VOT 55440 provided by Universiti Malaysia Terengganu (UMT)the SIPP Incentive sponsored by UMT
文摘For the first time,the MgH_(2)–NaAlH_(4)(ratio 4:1)destabilized system with CoTiO_(3) addition has been explored.The CoTiO_(3)-doped MgH_(2)–NaAlH_(4) sample begins to dehydrogenate at 130℃,which is declined by 40℃ compared to the undoped MgH_(2)–NaAlH_(4).Moreover,the de/rehydrogenation kinetics characteristics of the CoTiO_(3)-doped MgH_(2)–NaAlH_(4) were greatly ameliorated.With the inclusion of CoTiO_(3),the MgH_(2)–NaAlH_(4) composite absorbed 5.2 wt.%H_(2),higher than undoped MgH_(2)–NaAlH_(4).In the context of dehydrogenation,the CoTiO_(3)-doped MgH_(2)–NaAlH_(4) sample desorbed 2.6 wt.%H_(2),almost doubled compared to the amount of hydrogen desorbed from the undoped MgH_(2)–NaAlH_(4) sample.The activation energy obtained by the Kissinger analysis for MgH_(2) decomposition was significantly lower by 35.9 kJ/mol than the undoped MgH_(2)–NaAlH_(4) sample.The reaction mechanism demonstrated that new phases of MgCo and AlTi_(3) were generated in situ during the heating process and are likely to play a substantial catalytic function and be useful in ameliorating the de/rehydrogenation properties of the destabilized MgH_(2)–NaAlH_(4) system with the inclusion of CoTiO_(3).
基金financially supported by the National High Technology Research and Development Program of China (No.2006AA05Z132)the National Natural Science Foundation of China (No.51471054)
文摘The catalytic effects of ZrC powder on the dehydrogenation properties of LiAlH4 prepared by designed mixing processes were systematically investigated.The onset dehydrogenation temperatures for the 10 mol% ZrC-doped sample are 85.3 and 148.4℃for the first two dehydrogenation stages,decreasing by 90.7 and 57.8℃,respectively,compared with those of the as-received LiAIH4.The isothermal volumetric measurement indicates that adding ZrC powder could significantly enhance the desorption kinetics of LiAlH4.The reaction constant and Avrami index show that the first dehydrogenation stage is controlled by diffusion mechanism with nucleation rate gradually decreasing and the second stage is a freedom nucleation and subsequent growth process.The microstructures and phase transformation characterized by scanning electron microscopy(SEM),X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS) and Fourier transform infrared spectroscopy(FTIR) reveal that the improved desorption behavior of LiAlH4 is primarily due to the high density of surface defects and embedded catalyst particles on the surface of LiAlH4 particles during the high-energy mixing process.
