Oxygen reduction reaction (ORR) in fuel cells on carbon-based metal-free electrocatalysts by first-principles multiscale simulations.

为了提高ORR电催化活性，通过原子掺杂对结构进行修饰是提高活性的好方法。在这里，我们选择N掺杂的GDY来研究ORR活性。因此，本论文的研究目的主要集中在三个方面：（1）筛选合适的无金属原子掺杂到GDY上作为电催化剂，并进行ORR第一性原理多尺度模拟，通过对本征性质（如电子性质）的分析，找出无金属原子的掺杂原理。(2)考察了在水溶液中的ORR电催化活性。(3)从热力学和动力学水平分析了ORR反应路径。目前，我们已经研究了sp-N和吡啶N掺杂的GDY对ORR的电催化活性。为了模拟真实的实验条件，（1）在氮掺杂的GDY下使用石墨烯（G）作为支撑体以提高电极的导电性。(2)我们采用从头算分子动力学（AIMD）方法模拟了表面含有水的水环境，计算了ORR中间体的溶剂化能。最后，我们进行了自由能图（基于热力学分析），以证明和预测实验观察到的活动趋势的一系列材料。所有计算将使用原子技术（STATE）代码的模拟工具进行，并使用NEB方法研究ORR机制。

In order to improve the ORR electrocatalytic activity, by doping atoms to modification structure is good way to improve the activity. Here, we choose the N doped GDY to investigate the ORR activity. And So, my research purpose is focus on three issues, namely (1) screening the suitable metal-free atoms doped on GDY as electrocatalysts for ORR first-principles multiscale simulations and figure out the doping principle of metal-free atoms by analysis of the intrinsic properties (such as electronic properties). (2) investigating the ORR electrocatalytic activity in water condition. (3) analysis the ORR reaction paths in thermodynamics and kinetics level. At present, we have studied sp-N and pyridine N doped GDY to investigate the electrocatalytic activity of ORR. To simulate the real experiment condition, (1) Graphene (G) is applied as support under the N-doped GDY to enhance the electrode conductivity. (2) we used the ab inito molecular dynamics (AIMD) calculations to simulate the water environment with some H2O on surface to calculate the solvation energy of ORR intermediates. Finally, we performed the free energy diagram (based on thermodynamic analyses) to proving and predicting the experimentally observed activity trends for a range of materials. All calculations will be performed using simulation tool for atom technology (STATE) code and investigated the ORR mechanisms using NEB method.