MOE Key Laboratory of Spectrochemical Analysis and Instrumentation, State Key Laboratory of Physical Chemistry of Solid Surfaces, iChEM, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China.
Department of Physics, Research Institute for Biomimetics and Soft Matter, Xiamen University, Xiamen 361005, China.
Nat Commun. 2017 May 24;8:15447. doi: 10.1038/ncomms15447.
Surface molecular information acquired in situ from a catalytic process can greatly promote the rational design of highly efficient catalysts by revealing structure-activity relationships and reaction mechanisms. Raman spectroscopy can provide this rich structural information, but normal Raman is not sensitive enough to detect trace active species adsorbed on the surface of catalysts. Here we develop a general method for in situ monitoring of heterogeneous catalytic processes through shell-isolated nanoparticle-enhanced Raman spectroscopy (SHINERS) satellite nanocomposites (Au-core silica-shell nanocatalyst-satellite structures), which are stable and have extremely high surface Raman sensitivity. By combining operando SHINERS with density functional theory calculations, we identify the working mechanisms for CO oxidation over PtFe and Pd nanocatalysts, which are typical low- and high-temperature catalysts, respectively. Active species, such as surface oxides, superoxide/peroxide species and Pd-C/Pt-C bonds are directly observed during the reactions. We demonstrate that in situ SHINERS can provide a deep understanding of the fundamental concepts of catalysis.
从催化过程中获得的表面分子信息可以通过揭示结构-活性关系和反应机理，极大地促进高效催化剂的合理设计。拉曼光谱可以提供这种丰富的结构信息，但普通拉曼对检测吸附在催化剂表面的痕量活性物种不够敏感。在这里，我们通过壳层隔离纳米粒子增强拉曼光谱 (SHINERS) 卫星纳米复合材料 (Au 核硅壳纳米催化剂-卫星结构) 开发了一种用于原位监测多相催化过程的通用方法，该方法稳定且具有极高的表面拉曼灵敏度。通过将 operando SHINERS 与密度泛函理论计算相结合，我们确定了 CO 在 PtFe 和 Pd 纳米催化剂上氧化的工作机制，它们分别是典型的低温和高温催化剂。在反应过程中直接观察到表面氧化物、超氧化物/过氧化物物种和 Pd-C/Pt-C 键等活性物质。我们证明，原位 SHINERS 可以深入了解催化的基本概念。
