Identification and characterization of catalytic active sites are the prerequisites for an atomic-level understanding of the catalytic mechanism and rational design of high-performance heterogeneous catalysts. Indirect evidence in recent reports suggests that platinum (Pt) single atoms are exceptionally active catalytic sites. We demonstrate that infrared spectroscopy can be a fast and convenient characterization method with which to directly distinguish and quantify Pt single atoms from nanoparticles. In addition, we directly observe that only Pt nanoparticles show activity for carbon monoxide (CO) oxidation and water-gas shift at low temperatures, whereas Pt single atoms behave as spectators. The lack of catalytic activity of Pt single atoms can be partly attributed to the strong binding of CO molecules.

催化活性位点的鉴别与表征是在原子水平理解催化机理和合理设计出高性能的多相催化剂的前提条件。最近的研究论文间接表明，铂（Pt）单原子是特别活跃的催化位点。我们证实了红外光谱是一种快速便捷的表征方法，可直接将Pt单原子与纳米粒子分辨开来并对其进行量化。此外，我们正好观察到只有Pt纳米粒子在一氧化碳（CO）氧化与低温水煤气的转换中表现出活性，而Pt单原子并不起作用。Pt单原子没有催化活性可部分归因于CO分子的强力结合。

Science 9 October 2015:
Vol. 350 no. 6257 pp. 189-192
DOI: 10.1126/science.aac6368

http://www.sciencemag.org/content/350/6257/189.full