The role of additional ternary alloying elements on the performance of stationary TiFe-based hydrogen storage alloys was investigated based on first-principles density functional theory calculations.As a basic step fo...The role of additional ternary alloying elements on the performance of stationary TiFe-based hydrogen storage alloys was investigated based on first-principles density functional theory calculations.As a basic step for examinations,the site preference of each alloying element in the stoichiometric and nonstoichiometric B2TiFe compounds was clarified considering possible antisite defects.Based on the revealed site preference,the effect of various possible ternary elements on the hydrogen storage was examined by focusing on the formation enthalpies of TiFeH and TiFeH_(2) hydrides,which were closely related to the change in the location of plateaus in the pressure-composition-temperature curve.Several physical properties such as the volume expansion due to hydride formation were also examined to provide additional criteria for selecting optimum alloying conditions in future alloying design processes.Candidate alloying elements that maximize the grain boundary embrittlement due to the solute segregation were proposed for the enhanced initial activation of TiFe-based hydrogen storage alloys.展开更多
We perform first-principles calculations to investigate the structural, magnetic, electronic, and mechanical properties of face-centered cubic （fcc） Pull2 and fcc Pull3 using the full potential linearized augmented ...We perform first-principles calculations to investigate the structural, magnetic, electronic, and mechanical properties of face-centered cubic （fcc） Pull2 and fcc Pull3 using the full potential linearized augmented plane wave method （FP- LAPW） with the generalized gradient approximation （GGA） and the local spin density approximation （LSDA） taking account of both relativistic and strong correlation effects. The optimized lattice constant a0 = 5.371 A for fcc Pull2 and a0 = 5.343 A for fcc PuH3 calculated in the GGA ＋ sp （spin polarization） ＋ U （Hubbard parameter） ＋ SO （spin-orbit coupling） scheme are in good agreement with the experimental data. The ground state of fcc PuH3 is found to be slightly ferromagnetic. Our results indicate that fcc PuH2 is a metal while fcc PuH3 is a semiconductor with a band gap about 0.35 eV. We note that the SO and the strong correlation between localized Pu 5f electrons are responsible for the band gap of fcc PuH3. The bonds for PuH2 have mainly covalent character while there are covalent bonds in addition to apparent ionicity bonds for PuH3. We also predict the elastic constants of fcc PuH2 and fcc PuH3, which were not observed in the previous experiments.展开更多
Ni and carbon materials exhibit remarkable catalysis for the hydriding reaction of Mg.But the underlying mechanism of Ni/C hybrid catalysis is still unclear.In this work,density functional theory(DFT)calculation is ap...Ni and carbon materials exhibit remarkable catalysis for the hydriding reaction of Mg.But the underlying mechanism of Ni/C hybrid catalysis is still unclear.In this work,density functional theory(DFT)calculation is applied to investigate the effect of Ni/C co-incorporation on the hydriding reaction of Mg crystal.The morphology and crystal structure of the Ni/C co-incorporated Mg sample show that the coincorporated structure is credible.The transition state searching calculation suggests that both the incorporations of Ni and C are beneficial for the H_(2) dissociation.But Ni atom has a dramatic improvement for H_(2) dissociation and makes the H diffusion become limiting step of the hyriding reaction.The Ni dz_(2)orbit and H s orbit accept the electrons and combine together compactly,while the Ni d_(xy) orbit is half-occupied.The catalytic effect of Ni on H_(2) dissociation can be ascribed to the bridging effect of Ni d_(xy) orbit.The incorporation of C can weaken the over-strong interaction between Ni and H which hindered the H diffusion on Mg(0001).The Ni/C co-incorporated Mg(0001)shows the best performance during hyriding reaction compared with the clean and single incorporated Mg(0001).展开更多
The crystal structure,electronic structure,and superconductivity of copper hydrides at high pressure have been studied by ab initio calculation.Consistent with experimental report,results show that the predicted stoic...The crystal structure,electronic structure,and superconductivity of copper hydrides at high pressure have been studied by ab initio calculation.Consistent with experimental report,results show that the predicted stoichiometry Cu2H with the P-3m1 space group is stable above 16.8 GPa.The stoichiometry of CuH with the Fm-3m space group is predicted to be synthesized above 30 GPa,but it is metastable and dynamical instable up to 120 GPa.The electronic band calculations reveal that Cu2H is a good metal at a stable pressure range,whereas CuH is an insulator.Moreover,the other hydrogenrich compounds CuH2 and CuH3 are thermodynamically and dynamically unstable,respectively.The calculated superconducting transition temperature (Tc) of Cu2H at 40 GPa is 0.028 K by using the Allen-Dynes modified McMillan equation.展开更多
The reviving of the“Holy Grail”lithium metal batteries(LMBs)is greatly hindered by severe parasitic reactions between Li anode and electrolytes.Herein,first,we comprehensively summarize the failure mechanisms and pr...The reviving of the“Holy Grail”lithium metal batteries(LMBs)is greatly hindered by severe parasitic reactions between Li anode and electrolytes.Herein,first,we comprehensively summarize the failure mechanisms and protection principles of the Li anode.Wherein,despite being in dispute,the formation of lithium hydride(LiH)is demonstrated to be one of the most critical factors for Li anode pulverization.Secondly,we trace the research history of LiH at electrodes of lithium batteries.In LMBs,LiH formation is suggested to be greatly associated with the generation of H_(2)from Li/electrolyte intrinsic parasitic reactions,and these intrinsic reactions are still not fully understood.Finally,density functional theory calculations reveal that H_(2)adsorption ability of representative Li anode protective species(such as LiF,Li_(3)N,BN,Li_(2)O,and graphene)is much higher than that of Li and LiH.Therefore,as an important supplement of well-known lithiophilicity theory/high interfacial energy theory and three key principles(mechanical stability,uniform ion transport,and chemical passivation),we propose that constructing an artificial solid electrolyte interphase layer enriched of components with much higher H_(2)adsorption ability than Li will serve as an effective principle for Li anode protection.In summary,suppressing formation of LiH and H_(2)will be very important for cycle life enhancement of practical LMBs.展开更多
The mechanism of reaction CI2+2HBr=2HCI+Br2 has been carefully investigated with density functional theory (DFT) at B3LYP/6-311G** level. A series of three-centred and four-centred transition states have been obtained...The mechanism of reaction CI2+2HBr=2HCI+Br2 has been carefully investigated with density functional theory (DFT) at B3LYP/6-311G** level. A series of three-centred and four-centred transition states have been obtained. The activation energy (138.96 and 147.24 kJ/mol, respectively) of two bimolecular elementary reactions CI2+HBr→HCI+BrCI and BrCI+HBr→HCI+Br2 is smaller than the dissociation energy of CI2, HBr and BrCI, indicating that it is favorable for the title reaction occurring in the bimolecular form. The reaction has been applied to the chemical engineering process of recycling Br2 from HBr. Gaseous CI2 directly reacts with HBr gas, which produces gaseous mixtures containing Br2, and liquid Br2 and HCI are obtained by cooling the mixtures and further separated by absorption with CCI4. The recovery percentage of Br2 is more than 96%, and the CI2 remaining in liquid Br2 is less than 3.0%. The paper provides a good example of solving the difficult problem in chemical engineering with basic theory.展开更多
基金supported by the National Research Foundation of Korea(NRF)funded by Ministry of Science and ICT(Nos.NRF-2019M3E6A1103984 and NRF-2019M3D1A1079214)。
文摘The role of additional ternary alloying elements on the performance of stationary TiFe-based hydrogen storage alloys was investigated based on first-principles density functional theory calculations.As a basic step for examinations,the site preference of each alloying element in the stoichiometric and nonstoichiometric B2TiFe compounds was clarified considering possible antisite defects.Based on the revealed site preference,the effect of various possible ternary elements on the hydrogen storage was examined by focusing on the formation enthalpies of TiFeH and TiFeH_(2) hydrides,which were closely related to the change in the location of plateaus in the pressure-composition-temperature curve.Several physical properties such as the volume expansion due to hydride formation were also examined to provide additional criteria for selecting optimum alloying conditions in future alloying design processes.Candidate alloying elements that maximize the grain boundary embrittlement due to the solute segregation were proposed for the enhanced initial activation of TiFe-based hydrogen storage alloys.
基金Project supported by the National Natural Science Foundation of China (Grant No. 20971114)
文摘We perform first-principles calculations to investigate the structural, magnetic, electronic, and mechanical properties of face-centered cubic （fcc） Pull2 and fcc Pull3 using the full potential linearized augmented plane wave method （FP- LAPW） with the generalized gradient approximation （GGA） and the local spin density approximation （LSDA） taking account of both relativistic and strong correlation effects. The optimized lattice constant a0 = 5.371 A for fcc Pull2 and a0 = 5.343 A for fcc PuH3 calculated in the GGA ＋ sp （spin polarization） ＋ U （Hubbard parameter） ＋ SO （spin-orbit coupling） scheme are in good agreement with the experimental data. The ground state of fcc PuH3 is found to be slightly ferromagnetic. Our results indicate that fcc PuH2 is a metal while fcc PuH3 is a semiconductor with a band gap about 0.35 eV. We note that the SO and the strong correlation between localized Pu 5f electrons are responsible for the band gap of fcc PuH3. The bonds for PuH2 have mainly covalent character while there are covalent bonds in addition to apparent ionicity bonds for PuH3. We also predict the elastic constants of fcc PuH2 and fcc PuH3, which were not observed in the previous experiments.
基金This work is supported by the National Key R&D Program of China(Grant No.2017YFB0103002)National Natural Science Foundation of China(Grant Nos.51771056,51371056,51701043 and 52071141)+4 种基金Equipment Preresearch Field Foundation(Grant No.6140721040101)Equipment Preresearch Sharing Technology(No.41421060201)Changzhou Leading Talents Project(Grant No.CQ20183020)333 Project in Jiangsu Province and the Priority Academic Program Development(PAPD)of Jiangsu Higher Education Institutions,Fundamental Research Funds for the Central Universities(Grant No.2021MS051)Interdisciplinary Innovation Program of North China Electric Power University(grant number XM2112355).
文摘Ni and carbon materials exhibit remarkable catalysis for the hydriding reaction of Mg.But the underlying mechanism of Ni/C hybrid catalysis is still unclear.In this work,density functional theory(DFT)calculation is applied to investigate the effect of Ni/C co-incorporation on the hydriding reaction of Mg crystal.The morphology and crystal structure of the Ni/C co-incorporated Mg sample show that the coincorporated structure is credible.The transition state searching calculation suggests that both the incorporations of Ni and C are beneficial for the H_(2) dissociation.But Ni atom has a dramatic improvement for H_(2) dissociation and makes the H diffusion become limiting step of the hyriding reaction.The Ni dz_(2)orbit and H s orbit accept the electrons and combine together compactly,while the Ni d_(xy) orbit is half-occupied.The catalytic effect of Ni on H_(2) dissociation can be ascribed to the bridging effect of Ni d_(xy) orbit.The incorporation of C can weaken the over-strong interaction between Ni and H which hindered the H diffusion on Mg(0001).The Ni/C co-incorporated Mg(0001)shows the best performance during hyriding reaction compared with the clean and single incorporated Mg(0001).
基金supported by the National Key R&D Program of China (Grant No. 2018YFA0305900)National Natural Science Foundation of China (Grant Nos.51632002,11674122,51572108,11634004,11504127,11574109,11704143, and 11404134)+4 种基金Program for Changjiang Scholars and Innovative Research Team in University (No.IRT15R23)the 111 Project (Grant No.B12011)Jilin Provincial Science and Technology Development Project of China (Grant No.20170520116JH)the National Found for Fostering Talents of basic Science (Grant No.J1103202)Parts of calculations were performed in the High Performance Computing Center (HPCC) of Jilin University and TianHe-1(A) at the National Supercomputer Center in Tianjin.
文摘The crystal structure,electronic structure,and superconductivity of copper hydrides at high pressure have been studied by ab initio calculation.Consistent with experimental report,results show that the predicted stoichiometry Cu2H with the P-3m1 space group is stable above 16.8 GPa.The stoichiometry of CuH with the Fm-3m space group is predicted to be synthesized above 30 GPa,but it is metastable and dynamical instable up to 120 GPa.The electronic band calculations reveal that Cu2H is a good metal at a stable pressure range,whereas CuH is an insulator.Moreover,the other hydrogenrich compounds CuH2 and CuH3 are thermodynamically and dynamically unstable,respectively.The calculated superconducting transition temperature (Tc) of Cu2H at 40 GPa is 0.028 K by using the Allen-Dynes modified McMillan equation.
基金Taishan Scholars of Shandong Province,Grant/Award Number:ts201511063National Natural Science Foundation of China,Grant/Award Numbers:22102206,U22A20440+2 种基金Strategic Priority Research Program of Chinese Academy of Sciences,Grant/Award Number:XDA22010600Natural Science Foundation of Shandong Province,Grant/Award Number:ZR2021QB030Key-Area Research and Development Program of Guangdong Province,Grant/Award Number:2020B090919005。
文摘The reviving of the“Holy Grail”lithium metal batteries(LMBs)is greatly hindered by severe parasitic reactions between Li anode and electrolytes.Herein,first,we comprehensively summarize the failure mechanisms and protection principles of the Li anode.Wherein,despite being in dispute,the formation of lithium hydride(LiH)is demonstrated to be one of the most critical factors for Li anode pulverization.Secondly,we trace the research history of LiH at electrodes of lithium batteries.In LMBs,LiH formation is suggested to be greatly associated with the generation of H_(2)from Li/electrolyte intrinsic parasitic reactions,and these intrinsic reactions are still not fully understood.Finally,density functional theory calculations reveal that H_(2)adsorption ability of representative Li anode protective species(such as LiF,Li_(3)N,BN,Li_(2)O,and graphene)is much higher than that of Li and LiH.Therefore,as an important supplement of well-known lithiophilicity theory/high interfacial energy theory and three key principles(mechanical stability,uniform ion transport,and chemical passivation),we propose that constructing an artificial solid electrolyte interphase layer enriched of components with much higher H_(2)adsorption ability than Li will serve as an effective principle for Li anode protection.In summary,suppressing formation of LiH and H_(2)will be very important for cycle life enhancement of practical LMBs.
基金Acknowledgements This work was supported by the Natural Science Foundation of Education Committee of Jiang.su Province (Grant No. 99KJB150002).
文摘The mechanism of reaction CI2+2HBr=2HCI+Br2 has been carefully investigated with density functional theory (DFT) at B3LYP/6-311G** level. A series of three-centred and four-centred transition states have been obtained. The activation energy (138.96 and 147.24 kJ/mol, respectively) of two bimolecular elementary reactions CI2+HBr→HCI+BrCI and BrCI+HBr→HCI+Br2 is smaller than the dissociation energy of CI2, HBr and BrCI, indicating that it is favorable for the title reaction occurring in the bimolecular form. The reaction has been applied to the chemical engineering process of recycling Br2 from HBr. Gaseous CI2 directly reacts with HBr gas, which produces gaseous mixtures containing Br2, and liquid Br2 and HCI are obtained by cooling the mixtures and further separated by absorption with CCI4. The recovery percentage of Br2 is more than 96%, and the CI2 remaining in liquid Br2 is less than 3.0%. The paper provides a good example of solving the difficult problem in chemical engineering with basic theory.
