Marcella Nicholas, Liu Yang, Timoshenko Janis, Guan Erjia, Luneau Mathilde, Shirman Tanya, Plonka Anna M, van der Hoeven Jessi E S, Aizenberg Joanna, Friend Cynthia M, Frenkel Anatoly I
Department of Materials Science and Chemical Engineering, Stony Brook University, Stony Brook, New York 11794, USA.
Department of Chemistry, Stony Brook University, Stony Brook, New York 11794, USA.
Phys Chem Chem Phys. 2020 Sep 8;22(34):18902-18910. doi: 10.1039/d0cp02098b.
X-ray absorption spectroscopy is a common method for probing the local structure of nanocatalysts. One portion of the X-ray absorption spectrum, the X-ray absorption near edge structure (XANES) is a useful alternative to the commonly used extended X-ray absorption fine structure (EXAFS) for probing three-dimensional geometry around each type of atomic species, especially in those cases when the EXAFS data quality is limited by harsh reaction conditions and low metal loading. A methodology for quantitative determination of bimetallic architectures from their XANES spectra is currently lacking. We have developed a method, based on the artificial neural network, trained on ab initio site-specific XANES calculations, that enables accurate and rapid reconstruction of the structural descriptors (partial coordination numbers) from the experimental XANES data. We demonstrate the utility of this method on the example of a series of PdAu bimetallic nanoalloys. By validating the neural network-yielded metal-metal coordination numbers based on the XANES analysis by previous EXAFS characterization, we obtained new results for in situ restructuring of dilute (2.6 at% Pd in Au) PdAu nanoparticles, driven by their gas and temperature treatments.
X射线吸收光谱法是探测纳米催化剂局部结构的常用方法。X射线吸收光谱的一部分，即X射线吸收近边结构（XANES），是探测每种原子物种周围三维几何结构的一种有用方法，可替代常用的扩展X射线吸收精细结构（EXAFS），特别是在EXAFS数据质量受苛刻反应条件和低金属负载量限制的情况下。目前缺乏一种从XANES光谱定量测定双金属结构的方法。我们基于人工神经网络开发了一种方法，该方法通过从头算特定位点的XANES计算进行训练，能够从实验XANES数据中准确快速地重建结构描述符（部分配位数）。我们以一系列PdAu双金属纳米合金为例展示了该方法的实用性。通过基于先前EXAFS表征的XANES分析验证神经网络得出的金属-金属配位数，我们获得了关于稀（Au中2.6原子% Pd）PdAu纳米颗粒在气体和温度处理驱动下原位重构的新结果。
