Cu-Pt纳米颗粒去合金化过程中特征结构形成与演化的原子模拟

项目名称： Cu-Pt纳米颗粒去合金化过程中特征结构形成与演化的原子模拟

项目编号： No.51301066

项目类型： 青年科学基金项目

立项/批准年度： 2014

项目学科： 一般工业技术

项目作者： 邓磊

作者单位： 湖南农业大学

项目金额： 25万元

中文摘要： 电催化剂是决定燃料电池性能、寿命和成本的关键材料之一。去合金化制备的铂基纳米催化剂因其低铂载量和高氧还原活性受到重点关注。铂基纳米催化剂的高氧还原活性与去合金化过程中特征结构的形成密不可分，但长时间去合金化处理中非贵金属的流失会导致特征结构退化。去合金化过程中特征结构形成与演化的微观过程、物理机制、影响因素等问题的解决是调控铂基纳米催化剂结构与性能的关键。去合金化行为本质上是非贵金属的选择性溶解和铂的表面扩散。由于电位、颗粒形貌、成分、化学有序度等因素或独立或协同地影响表面原子溶解或扩散能垒，仅采用实验方法难以揭示去合金化动态过程和微观机理。本项目拟采用嵌入原子多体势计算原子表面结合能，利用动力学蒙特卡洛方法模拟铜铂颗粒去合金化过程中特征结构的形成与演化及其影响因素以揭示纳米尺度去合金化机理，建立微观结构演化与极化曲线、氧还原活性面积之间的联系，为设计铂基纳米电催化剂提供理论基础。

中文关键词： 原子模拟；去合金化；氧还原反应；多重孪晶纳米粒子；铂壳纳米催化剂

英文摘要： Electrocatalyst is one of the key materials in low-temperature fuel cells, which determines the performance, lifetime and cost of the fuel cells. Very recently, Pt based core-shell structured electrocatalysts have attracted increasing attention due to their unique advantages in reducing Pt loading and improving the oxygen reduction activity. Electrochemically dealloying is the most promising method for synthesis of Pt based core-shell nanocatalysts. While the durability of dealloyed Pt alloys is tested under voltage-cycling conditions. The oxygen reduction activity and durability of Pt based nanocatalyst are strongly influenced by the formation and evolution of the characteristic structures during dealloying process, thus the dealloying mechanism is the key to optimizing electrocatalyst. Dealloying behavior refers to the selective dissolution of the non-noble metal and the surface diffusion of Pt. The dissolution or diffusion barriers are closely related to potentials and surface binding energy, which is local coordination-dependent and related to the morphology, composition, and chemical ordering of nanoparticle. Most of these factors can hardly be measured by experimental means, so that there is still a lack of deep understanding of dealloying mechanism. In this project, the embedded atom method will be use to

英文关键词： Atomistic Simulations；Dealloying；Oxygen Reduction Reaction；Multiply-twinned Nanoparticles；Pt-shell Nanocatalysts