质子交换膜燃料电池催化剂组件BN催化剂设计

摘要自从 ORR 催化剂被发现以来，经过不断的研究和探寻，人们已找到了许多新型催化剂的种类。石墨烯作为一种新型纳米材料，特殊的单原子层结构使其拥有丰富而特殊的性质。通过元素掺杂，可使其功能化，进而具有良好的催化能力。氮化硼与石墨烯具有着相同的结构，为探寻高效的 ORR 催化剂，研究不同金属元素掺杂的氮化硼对催化氧气还原反应的影响是很有意义的，这有利于我们设计并开发新型 ORR 催化剂。本文在软件 Materials Studio 的模拟下，采用第一性原理的密度泛函理论，分别对金属（Pt、Pd、Au）分别掺杂氮化硼的 N 位和 B 位作为 ORR 催化剂进行了系统的研究。通过分析氧气还原反应中间产物的吸附能和反应过程中发生的能量变化，我们发现 B 位掺杂 Pd 氮化硼催化剂符合吸附能不能太强以及太弱的要求，并在 1。23V 的高电势下，具有着较低的热力学能垒，这表明其只需要提供较低的能量，就能促使氧气还原反应的进行。为了表征其物理本质，我们分析了氧气还原反应的中间产物的电荷数以及掺杂金属元素的 d 带，进而从电子的角度解释了吸附现象。在此，通过掺杂，我们实现了功能化氮化硼，并表明 B 位掺杂 Pd 氮化硼催化剂可应用于未来燃料电池阴极催化剂。80799

毕业论文关键词：金属掺杂氮化硼；氧气还原反应；催化剂；第一性原理

Abstract Since the discovery of the ORR catalysts, it has received great attention to develop the novel electrocatalysts for the future PEMFC。 The two-dimensional graphene has been functionalized by mean of the metal doping and possessed the superior ORR activity。 Similarly, since BN has the same structure of the graphene, it is very meaningful to study on the ORR activity of the functional BN with different metal doping in order to seek the efficient ORR catalyst。 In this paper, based on the simulation of Materials studio, using the density functional theory calculations, we systematic study the BN catalyst with the transition metals (Pt, Pd, Au) doping where different doping sites (the B or N vacancy) are considered。 By calculating the adsorption energy of ORR intermediate, we find that B-Pd doped BN catalyst possess the suitable adsorption ability。 Since the ORR catalyst must activate the O2 molecule and remove the oxide adsorbates, the adsorption energy of the optimal catalysts cannot be too strong or too weak。 Therefore, the B-Pd doped BN is expected to be good ORR catalyst。 Besides the adsorption energy, the thermodynamic energy barriers of the ORR steps are considered。 At the potential of 1。23V, the B-Pd doped BN has the lowest thermodynamic energy barrier among the other functional BN。 In order to understand the underlying mechanism, the Mulliken charge of ORR intermediates and the d-density of states of the metal element have been analyzed。 From the Mulliken, it is observed that the more the electron transfer and the higher the d band toward the Fermi energy makes the larger the adsorption energy。 The electronic analysis is consistent with the aforementioned results。 In a word, our results demonstrate that the B-Pd doped BN catalyst is an excellent ORR catalyst。

Keywords: metal doped BN; oxygen reduction reaction; first-principle; calculation

第一章绪论 1

1。1 引言 1

1。2 燃料电池 1

1。2。1 燃料电池的组成 1

1。2。2 燃料电池的种类 1

1。3 质子交换膜燃料电池催化剂组件BN催化剂设计:http://www.youerw.com/jixie/lunwen_94037.html