Nolte P, Stierle A, Jin-Phillipp N Y, Kasper N, Schulli T U, Dosch H
Max-Planck-Institut für Metallforschung, Heisenbergstrasse 3, D-70569 Stuttgart, Germany.
Science. 2008 Sep 19;321(5896):1654-8. doi: 10.1126/science.1160845.
The microscopic insight into how and why catalytically active nanoparticles change their shape during oxidation and reduction reactions is a pivotal challenge in the fundamental understanding of heterogeneous catalysis. We report an oxygen-induced shape transformation of rhodium nanoparticles on magnesium oxide (001) substrates that is lifted upon carbon monoxide exposure at 600 kelvin. A Wulff analysis of high-resolution in situ x-ray diffraction, combined with transmission electron microscopy, shows that this phenomenon is driven by the formation of a oxygen-rhodium-oxygen surface oxide at the rhodium nanofacets. This experimental access into the behavior of such nanoparticles during a catalytic cycle is useful for the development of improved heterogeneous catalysts.
从微观层面洞察催化活性纳米颗粒在氧化和还原反应过程中如何以及为何改变其形状，是多相催化基础理解中的一个关键挑战。我们报道了在氧化镁（001）衬底上铑纳米颗粒的氧诱导形状转变，这种转变在600开尔文下暴露于一氧化碳时会消除。结合透射电子显微镜的高分辨率原位X射线衍射的伍尔夫分析表明，这种现象是由铑纳米面处氧 - 铑 - 氧表面氧化物的形成驱动的。这种对纳米颗粒在催化循环过程中行为的实验性研究，对于开发改进的多相催化剂很有用。
