Kumar E Mathan, Rajkamal A, Thapa Ranjit
SRM Research Institute & Department of Physics and Nanotechnology, SRM University, Kattankulathur, 603203, Tamil Nadu, India.
Sci Rep. 2017 Nov 14;7(1):15550. doi: 10.1038/s41598-017-15694-x.
First-principles based calculations are performed to investigate the dehydrogenation kinetics considering doping at various layers of MgH (110) surface. Doping at first and second layer of MgH (110) has a significant role in lowering the H desorption (from surface) barrier energy, whereas the doping at third layer has no impact on the barrier energy. Molecular dynamics calculations are also performed to check the bonding strength, clusterization, and system stability. We study in details about the influence of doping on dehydrogenation, considering the screening factors such as formation enthalpy, bulk modulus, and gravimetric density. Screening based approach assist in finding Al and Sc as the best possible dopant in lowering of desorption temperature, while preserving similar gravimetric density and Bulk modulus as of pure MgH system. The electron localization function plot and population analysis illustrate that the bond between Dopant-Hydrogen is mainly covalent, which weaken the Mg-Hydrogen bonds. Overall we observed that Al as dopant is suitable and surface doping can help in lowering the desorption temperature. So layer dependent doping studies can help to find the best possible reversible hydride based hydrogen storage materials.
进行基于第一性原理的计算，以研究考虑在MgH(110)表面各层进行掺杂时的脱氢动力学。在MgH(110)的第一层和第二层进行掺杂对降低（从表面）氢解吸的势垒能量具有重要作用，而在第三层进行掺杂对势垒能量没有影响。还进行了分子动力学计算，以检查键合强度、团簇化和系统稳定性。我们详细研究了掺杂对脱氢的影响，考虑了诸如形成焓、体积模量和重量密度等筛选因素。基于筛选的方法有助于找到Al和Sc作为降低解吸温度的最佳掺杂剂，同时保持与纯MgH系统相似的重量密度和体积模量。电子定位函数图和布居分析表明，掺杂剂 - 氢之间的键主要是共价键，这削弱了镁 - 氢键。总体而言，我们观察到Al作为掺杂剂是合适的，表面掺杂有助于降低解吸温度。因此，基于层依赖性的掺杂研究有助于找到最佳的基于可逆氢化物的储氢材料。
