Liu Xiaokang, Ao Chengcheng, Shen Xinyi, Wang Lan, Wang Sicong, Cao Linlin, Zhang Wei, Dong Jingjing, Bao Jun, Ding Tao, Zhang Lidong, Yao Tao
National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei 230029, P. R. China.
School of National Defense Science and Technology, Southwest University of Science and Technology, Mianyang 621010, P. R. China.
Nano Lett. 2020 Nov 11;20(11):8319-8325. doi: 10.1021/acs.nanolett.0c03475. Epub 2020 Oct 22.
The atomic-level understanding of the dynamic evolution of the surface structure of bimetallic nanoparticles under industrially relevant conditions provides a key guide for improving their catalytic performance. Here, we exploit X-ray absorption fine structure spectroscopy to determine the dynamic surface reconstruction of Cu/Au bimetallic alloy where single-atom Cu was embedded on the Au nanoparticle, under electrocatalytic conditions. We identify the migration of isolated Cu atoms from the vertex position of the Au nanoparticle to the stable (100) plane of the Au first atom layer, when the reduction potential is applied. Density functional theory calculations reveal that the surface atom migration would significantly modulate the Au electronic structure, thus serving as the real active site for the catalytic performance. These findings demonstrate the real structural change under electrochemical conditions and provide guidance for the rational design of high-activity bimetallic nanocatalysts.
在工业相关条件下，对双金属纳米颗粒表面结构动态演化的原子级理解为改善其催化性能提供了关键指导。在此，我们利用X射线吸收精细结构光谱来确定在电催化条件下，单原子铜嵌入金纳米颗粒的Cu/Au双金属合金的动态表面重构。我们发现，当施加还原电势时，孤立的铜原子会从金纳米颗粒的顶点位置迁移到金第一原子层的稳定（100）平面。密度泛函理论计算表明，表面原子迁移会显著调节金的电子结构，从而成为催化性能的真正活性位点。这些发现证明了电化学条件下的实际结构变化，并为高活性双金属纳米催化剂的合理设计提供了指导。
