基于XAS原位测试和定量分析的Pt肤氧还原电催化剂结构与性能优化

氢氧燃料电池商业化的一个重要挑战就是降低氧还原反应中Pt的负载量。由Pd或Au基底粒子支撑的超薄（大概1-2原子层）Pt肤可以实现非常高Pt的利用，然而调控其活性/稳定性的机制仍然不清楚。在本项目中，我们计划以同步辐射XAS的原位测试和定量分析为主要手段，以基底粒子结构（尺寸、晶面比例和晶面缺陷）的可控合成为先导，去逐步厘清基底粒子结构对Pt肤键长的影响，Pt肤键长与活性的关系，稳定性衰减时起决定作用的基底粒子或Pt肤变化，从而实现从基底粒子到Pt肤的针对性结构优化以得到高性能。本课题的顺利实施，可以为高效Pt肤氧还原电催化剂的理性开发奠定基础，从而推动氢氧燃料电池在电动汽车中的实际应用。

One of the great challenges in the commercialization of H2-O2 fuel cells is to reduce Pt loading in the oxygen-reduction reaction. Ultrathin (near 1-2 atomic-layer thickness) Pt-skin, supported on Pd or Au substrate-nanoparticles, can realize very high Pt utilization; however, the mechanism for tuning its catalytic activity/stability remains unclear. In this project, based on the in-situ measurement and quantitative analysis of synchrotron radiation XAS and started by the controllable synthesis of Pd and Au substrate-nanoparticle structure (such as particle size, facet ratio and facet defect), we plan to gradually clarify the influence of substrate-nanoparticle structure on Pt-skin bond distance, the correlation between Pt-skin bond distance and oxygen-reduction activity, and the structural changes of substrate-nanoparticle or Pt-skin in charge of durability degradation, aiming for the targeted structural optimization ranging from substrate-nanoparticle to Pt-skin toward high-performance. The successful achievement of this project can establish a fundamental basis for the reasonable development of high-performance Pt-skin oxygen-reduction electrocatalysts, which paves the way for the practical application of H2-O2 fuel cells in electric vehicle.