论文总字数：22777字

摘 要

氢能是21世纪最有未来的新能源，而储氢材料则是开发氢能的核心，在众多的储氢材料中，镁基储氢材料是目前最有实用潜力的一类储氢材料，其研究历史也是非常深远，但是动力学上脱氢速率缓慢限制了其实际应用，因此人们期望通过催化等手段来改善其储氢性能，在此背景下，本文通过第一性原理来研究MgH₂(110)晶面在结晶态Ni的催化下的脱氢行为，为设计更高效的催化手段提供思路。

本文首先介绍了储氢材料的发展历程和类别，并详细说明了计算方法和理论支撑。整个实验过程是通过第一性原理的方法，研究镍(111)晶面催化MgH₂(110)晶面的脱氢过程，建模并计算出每一个基元反应的热力学焓变与动力学能垒。本文对比了纯MgH₂和在Ni催化条件下的MgH₂的脱氢行为，发现对于纯MgH₂而言，H₂分子从MgH₂表面解离这个过程是脱氢反应的速控步骤，其动力学能垒高达2.31 eV；而在Ni的催化下，H从MgH₂晶格中脱出的过程被大大加速，而H₂在催化剂表面的解离过程变成了新的速度控制步骤，该步骤的动力学能垒只有1.15 eV，相比于纯MgH₂下降了50 % 左右，从而大大改善了MgH₂的脱氢动力学性能。这一结果与以往的实验结论基本符合。这个实验结果也为新型催化剂的研究提供新的理论依据。

关键词：第一性原理、储氢材料、MgH₂(110)晶面、脱氢动力学性能

Abstract

Hydrogen energy is the most promising energy source in the 21st century, and the hydrogen storage is the key to promote it. Among the many hydrogen storage materials, magnesium-based hydrogen storage materials are the most potential type of hydrogen storage materials, and it has been researched for many years. But the sluggish dehydrogenation kinetic property restricted its practical application, so many researchers devoted themselves to develop new catalysis to improve the kinetic performance of MgH₂. Under this background, we studied the dehydrogenation performance of MgH₂(110) crystal surface catalyzed by crystalline Ni by first principles. We expected to provide novel ideals for designing more efficient catalyst.

Firstly, we introduced the development history and categories of hydrogen storage materials, and details of the calculation method and theoretical basis were also introduced. In the experimental section, we firstly calculated the dehydrogenation enthalpy change and activation energy by the nudged elastic band (NEB) method based on the first principles. Then the dehydrogenation performance of the crystalline Ni catalyzed MgH₂(110) surface was studied for comparison. The primitive reactions of the catalyzed system were studied systematically to find the speed control step. Finally, we found that the desorption of H₂ molecular from MgH₂(110) surface is the speed control step in the pristine MgH₂ system, and the activation energy of this step was about 2.31 eV. But this step was accelerated rapidly after catalyzed by the crystalline Ni. The speed control step changed to the desorption of H₂ molecular from the surface of the catalyst in the catalyzed system, and the activation energy of this step was about 1.15 eV, which was about 50 % lower than that of pure MgH₂(110). This result is basically consistent with the previous experimental conclusions and could also provide a new theoretical basis for the development of new catalysts in the hydrogen storage fields.

Key words: first principles, hydrogen storage materials, MgH₂ (110) crystal surface, dehydrogenation kinetic performance

目录

摘要 I

Abstract II

第一章 绪论 1

1.1 储氢材料概述 1

1.2 储氢材料发展现状 2

1.2.1 储氢材料的类别 2

1.2.2 金属储氢材料 3

1.2.3 镁基储氢材料 3

1.2.4 镁基储氢材料的催化 4

1.3 储氢材料领域内常见的第一性原理案例 6

1.4 研究的目的、意义和内容 6

1.4.1 研究的目的和内容 6

1.4.2. 研究意义 7

第二章 理论计算方法 8

2.1 VASP软件简介 9

2.2 第一性原理简介 9

2.3 密度泛函理论简介 10

2.3 交换关联泛函简介 11

第三章 计算结果和模型 12

3.1 纯MgH₂(110)表面脱氢性能研究 12

3.1.1 纯MgH₂的晶体结构 12

3.1.2 纯MgH₂(110)表面 12

3.1.3 纯MgH₂脱氢过程(NEB) 14

3.2 Ni掺杂在MgH₂表面的性能研究 14

3.2.1 MgH₂(110)/Ni(111)界面的构建 14

3.2.2 寻找合适的层间距 17

3.2.3 计算H扩散能垒 18

3.2.4 H原子在Ni内部的迁移 20

3.2.5 H原子在Ni表面解离 22

第四章 总结与展望 24

4.1 总结 24

4.2 展望 24

参考文献 26

致谢 30

绪论

1.1 储氢材料概述

由于化石燃料长期的大量消耗，导致了全球生态被严重污染；因此，如何有效利用化石能源，减缓能源消耗过度，如何使用新能源取代石油，成为全球性议题。发展清洁的新能源逐渐成为人们的共识，在寻找新能源的过程中，氢能由于其不依赖化石燃料、无毒无害且能廉价制取、储量丰富的特性而受到人们越来越多的关注。

经过长年的研究和发展，储氢的方式和材料已经有了很大丰富，从储氢方式这一方面来看，基本可划分为3类：

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