NiF_2掺杂对MgH_2解氢性能影响机制研究
|
摘要
采用第一原理赝势平面波方法,计算分析了NiF_2掺杂对MgH_2解氢性能的影响,合金形成热计算结果表明:F原子优先占据MgH_2中的H原子位,无论F原子占H位还是占居间隙位置都能形成更为稳定的结构。F原子占据MgH_2间隙位置时,H原子的解离能明显降低,说明F原子占据间隙位置时,能够改善MgH_2体系的解氢性能。Ni原子置换MgH_2中的Mg原子后,MgH_2体系的形成热与H原子的解离能都降低,说明在MgH_2体系中加入Ni原子能够改善MgH_2体系的解氢性能。电子态密度,交叠聚居数结果表明:F或Ni原子掺杂后MgH_2解氢能力增加,归因于MgH_2体系费米能级附近的能隙变窄以及H-H原子的键长变短。合金形成热及交叠聚居数结果表明,Mg与F元素容易成键形成更为稳定的Mg F2化合物,Ni元素与MgH_2形成不稳定的Mg2Ni H4化合物,从微观层面证实了NiF_2的加入促进化学反应NiF_2+3MgH2=Mg F2+Mg2Ni H4+H2的进行,形成更为稳定的Mg F2和不稳定的Mg2Ni H4化合物,从而改善MgH_2体系的解氢性能。
A first-principles plane-wave pseudopotential method was used. The mechanism of NiF_2 doping on the improvement of dehydrogenating properties of MgH_2 systems was studied. Alloy formation heat calculation results showed that F atom preferred to occupy the H atom site of MgH_2,whether F atom replaced H atom or occupied interstitial site MgH_2 could form a more stable structure. When F atom occupied the interstitial site of MgH_2,the dissociation energy of H atom was obviously reduced. It meant that when the F atom occupied the interstitial site,the dehydrogenation properties of the MgH_2 system were improved. When Ni atom replaced Mg atom,both the formation heat of the MgH_2 system and the dissociation energy of H atom were reduced. It meant that after Ni atom replaced Mg atom,the dehydrogenation properties of the MgH_2 system were improved. After analyzing the densities of states( DOS) and overlap populations,it was found that after doped with F or Ni atom the dehydrogenation properties of MgH_2 were increased,it was attributed to the narrow of the energy gap near the Fermi energy level and the shortening of H-H bond length. The calculation results of alloy formation heat and overlap populations showed that Mg and F elements tended to form more stable MgF2 compound,and Ni elements and MgH_2 formed unstable Mg2 Ni H4 compound. It showed that the addition of NiF_2 could accelerate the chemical reaction of NiF_2+ 3 MgH_2=MgF2+ Mg2 Ni H4+ H2,a more stable MgF2 and unstable Mg2 Ni H4 compound were formed to improve the hydrogenation of the MgH_2 system.
A first-principles plane-wave pseudopotential method was used. The mechanism of NiF_2 doping on the improvement of dehydrogenating properties of MgH_2 systems was studied. Alloy formation heat calculation results showed that F atom preferred to occupy the H atom site of MgH_2,whether F atom replaced H atom or occupied interstitial site MgH_2 could form a more stable structure. When F atom occupied the interstitial site of MgH_2,the dissociation energy of H atom was obviously reduced. It meant that when the F atom occupied the interstitial site,the dehydrogenation properties of the MgH_2 system were improved. When Ni atom replaced Mg atom,both the formation heat of the MgH_2 system and the dissociation energy of H atom were reduced. It meant that after Ni atom replaced Mg atom,the dehydrogenation properties of the MgH_2 system were improved. After analyzing the densities of states( DOS) and overlap populations,it was found that after doped with F or Ni atom the dehydrogenation properties of MgH_2 were increased,it was attributed to the narrow of the energy gap near the Fermi energy level and the shortening of H-H bond length. The calculation results of alloy formation heat and overlap populations showed that Mg and F elements tended to form more stable MgF2 compound,and Ni elements and MgH_2 formed unstable Mg2 Ni H4 compound. It showed that the addition of NiF_2 could accelerate the chemical reaction of NiF_2+ 3 MgH_2=MgF2+ Mg2 Ni H4+ H2,a more stable MgF2 and unstable Mg2 Ni H4 compound were formed to improve the hydrogenation of the MgH_2 system.
引文
[1] Ouyang L Z,Cao Z J,Wang H,Hu R Z,Zhu M. Application of dielectric barrier discharge plasma-assisted milling in energy storage materials—A review[J]. J.Alloys Compd.,2017,(691):422.
[2] Ismail M. Effect of La Cl3addition on the hydrogen storage properties of MgH2[J]. Energy,2015,79(1):177.
[3] Song Y,Guo Z X,Yang R. Influence of selected alloying elements on the stability of magnesium dihydride for hydrogen storage applications MgH2[J]. Physical Review Letters B,2014,12(3):132106.
[4] Zaluski L,Zaluska A,Strom-Olsen J O. Hydrogen absorption in nanocrystalline Mg2Ni formed by mechanical alloying[J]. J. Alloys Compd.,1995,217:24.
[5] Suda S. Studies on the fluorination method for improving surface properties and characteristics of AB5-typesof hydrides[J]. J. Alloys Compd.,2002,330:627.
[6] Zhou D W,Zhang J,Liu J S. Mechanism of dehydrogenating properties of Ni doped MgH2systems[J]. Chinese Journal of Nonferrous Metals,2009,19(2):315.(周惦武,张健,刘金水. Ni掺杂MgH2体系解氢性能的机制[J].中国有色金属学报,2009,19(2):315.)
[7] Yuan J,Zhou D W,Wei H W. First-principles investigation of Ti F3solution hydrogen thermodynamic effects on MgH2[J]. Chinese Journal of Nonferrous Metals,2016,26(7):1480.(袁江,周惦武,魏红伟. Ti F3对MgH2体系解氢热力学影响的第一性原理研究[J].中国有色金属学报,2016,26(7):1480.)
[8] Zhang J,Tang W,Shao L,Yu X F,Long C G,Chen J.Microstructures and dehydrogenation properties of ballmilled MgH2-K2Ti6O13-Ni composite systems[J]. Journal of Materials Engineering,2016,44(11):101.(张健,汤旺,邵磊,余小峰,龙春光,陈荐. MgH2-K2Ti6O13-Ni球磨复合体系的微观结构与解氢性能[J].材料工程,2016,44(11):101.)
[9] Jin S A,Shim J H,Cho Y W,Yi K W. Dehydrogenation and hydrogenation characteristics of MgH2with transition metal fluorides[J]. J. Power Sources,2007,172(1/2):859.
[10] Liu Y C,Gao L J. Effects of Co concentration on the mechanical properties of Ni Al[J]. Rare Metals and Cemented Carbides,2013,41(6):33.(刘友成,高丽洁.合金化元素Co浓度对Ni Al力学性能的影响[J].稀有金属与硬质合金,2013,41(6):33.)
[11] Lindan P L D,Segall M D,Probert M J. First-principles simulation:ideas illustrations and the CASTEP code[J]. Phys:Condens. Matter,2002,14(11):2717.
[12] Miwa K,Ohba N,Towata S I,Nakamori Y,Orimo S I.First-principles study on lithium borohydride Li BH4[J].Phys. Rev. B,2004,69:245120.
[13] Li C,Zhou D W,Peng P,Wan L. First-principles calculation on dehydrogenating properties of Li BH4-X(X=O,F,Cl)systems[J]. Acta Chimica Sinica,2012,70(1):71.(李闯,周惦武,彭平,万隆. Li BH4-X(X=O,F和Cl)体系解氢性能的第一原理计算[J].化学学报,2012,70(1):71.)
[14] Yin L C,Wang P,Fang Z Z,Cheng H M. Thermodynamically tuning Li BH4by fluorine anion doping for hydrogen storage:a density functional study[J]. Chem.Phys. Lett.,2008,450:318.
[15] Nakamura H,Nguyen-Manh D,Pettifor D G. Electronic structure and energetics of La Ni5,α-La2Ni10H andβ-La2Ni10H14[J]. J. Alloys Compd.,1998,281:81.
[16] Zhou D W,Peng P,Liu J S. First-principles calculation of hydrogenating properties of MgH2-V systems[J].Science in China Series E,2006,49(2):129.
[17] Bogdanovic'a B,Bohmhammelb K,Christb B,Reisera A,Schlichtea K,Vehlena R,Wolfb U. Thermodynamic investigation of the magnesium-hydrogen system[J]. J. Alloys Compd.,1999,282:84.
[18] Xia L S,Zhu S H. Mechanism of dehydrogenation of Al-LiBH4systems[J]. Chinese Journal of Rare Metals,2013,37(7):531.(夏罗生,朱树红. Al-LiBH4体系解氢性能的机制研究[J].稀有金属,2013,37(7):531.)
[19] Wang J,Wang G,Zhao J. Density-functional study of Aun(n=2~20)clusters:lowest-energy structures and electronic properties[J]. Phys. Rev. B, 2002,66:035418.
[2] Ismail M. Effect of La Cl3addition on the hydrogen storage properties of MgH2[J]. Energy,2015,79(1):177.
[3] Song Y,Guo Z X,Yang R. Influence of selected alloying elements on the stability of magnesium dihydride for hydrogen storage applications MgH2[J]. Physical Review Letters B,2014,12(3):132106.
[4] Zaluski L,Zaluska A,Strom-Olsen J O. Hydrogen absorption in nanocrystalline Mg2Ni formed by mechanical alloying[J]. J. Alloys Compd.,1995,217:24.
[5] Suda S. Studies on the fluorination method for improving surface properties and characteristics of AB5-typesof hydrides[J]. J. Alloys Compd.,2002,330:627.
[6] Zhou D W,Zhang J,Liu J S. Mechanism of dehydrogenating properties of Ni doped MgH2systems[J]. Chinese Journal of Nonferrous Metals,2009,19(2):315.(周惦武,张健,刘金水. Ni掺杂MgH2体系解氢性能的机制[J].中国有色金属学报,2009,19(2):315.)
[7] Yuan J,Zhou D W,Wei H W. First-principles investigation of Ti F3solution hydrogen thermodynamic effects on MgH2[J]. Chinese Journal of Nonferrous Metals,2016,26(7):1480.(袁江,周惦武,魏红伟. Ti F3对MgH2体系解氢热力学影响的第一性原理研究[J].中国有色金属学报,2016,26(7):1480.)
[8] Zhang J,Tang W,Shao L,Yu X F,Long C G,Chen J.Microstructures and dehydrogenation properties of ballmilled MgH2-K2Ti6O13-Ni composite systems[J]. Journal of Materials Engineering,2016,44(11):101.(张健,汤旺,邵磊,余小峰,龙春光,陈荐. MgH2-K2Ti6O13-Ni球磨复合体系的微观结构与解氢性能[J].材料工程,2016,44(11):101.)
[9] Jin S A,Shim J H,Cho Y W,Yi K W. Dehydrogenation and hydrogenation characteristics of MgH2with transition metal fluorides[J]. J. Power Sources,2007,172(1/2):859.
[10] Liu Y C,Gao L J. Effects of Co concentration on the mechanical properties of Ni Al[J]. Rare Metals and Cemented Carbides,2013,41(6):33.(刘友成,高丽洁.合金化元素Co浓度对Ni Al力学性能的影响[J].稀有金属与硬质合金,2013,41(6):33.)
[11] Lindan P L D,Segall M D,Probert M J. First-principles simulation:ideas illustrations and the CASTEP code[J]. Phys:Condens. Matter,2002,14(11):2717.
[12] Miwa K,Ohba N,Towata S I,Nakamori Y,Orimo S I.First-principles study on lithium borohydride Li BH4[J].Phys. Rev. B,2004,69:245120.
[13] Li C,Zhou D W,Peng P,Wan L. First-principles calculation on dehydrogenating properties of Li BH4-X(X=O,F,Cl)systems[J]. Acta Chimica Sinica,2012,70(1):71.(李闯,周惦武,彭平,万隆. Li BH4-X(X=O,F和Cl)体系解氢性能的第一原理计算[J].化学学报,2012,70(1):71.)
[14] Yin L C,Wang P,Fang Z Z,Cheng H M. Thermodynamically tuning Li BH4by fluorine anion doping for hydrogen storage:a density functional study[J]. Chem.Phys. Lett.,2008,450:318.
[15] Nakamura H,Nguyen-Manh D,Pettifor D G. Electronic structure and energetics of La Ni5,α-La2Ni10H andβ-La2Ni10H14[J]. J. Alloys Compd.,1998,281:81.
[16] Zhou D W,Peng P,Liu J S. First-principles calculation of hydrogenating properties of MgH2-V systems[J].Science in China Series E,2006,49(2):129.
[17] Bogdanovic'a B,Bohmhammelb K,Christb B,Reisera A,Schlichtea K,Vehlena R,Wolfb U. Thermodynamic investigation of the magnesium-hydrogen system[J]. J. Alloys Compd.,1999,282:84.
[18] Xia L S,Zhu S H. Mechanism of dehydrogenation of Al-LiBH4systems[J]. Chinese Journal of Rare Metals,2013,37(7):531.(夏罗生,朱树红. Al-LiBH4体系解氢性能的机制研究[J].稀有金属,2013,37(7):531.)
[19] Wang J,Wang G,Zhao J. Density-functional study of Aun(n=2~20)clusters:lowest-energy structures and electronic properties[J]. Phys. Rev. B, 2002,66:035418.