Department of Chemistry, Tufts University, 62 Talbot Avenue, Medford, MA 02155, USA.
Science. 2012 Mar 9;335(6073):1209-12. doi: 10.1126/science.1215864.
Facile dissociation of reactants and weak binding of intermediates are key requirements for efficient and selective catalysis. However, these two variables are intimately linked in a way that does not generally allow the optimization of both properties simultaneously. By using desorption measurements in combination with high-resolution scanning tunneling microscopy, we show that individual, isolated Pd atoms in a Cu surface substantially lower the energy barrier to both hydrogen uptake on and subsequent desorption from the Cu metal surface. This facile hydrogen dissociation at Pd atom sites and weak binding to Cu allow for very selective hydrogenation of styrene and acetylene as compared with pure Cu or Pd metal alone.
反应物的易离解和中间体的弱结合是高效和选择性催化的关键要求。然而，这两个变量密切相关，通常不允许同时优化这两个性质。通过使用解吸测量结合高分辨率扫描隧道显微镜，我们表明，Cu 表面中的单个孤立的 Pd 原子大大降低了氢在 Cu 金属表面上的吸收和随后的解吸的能量势垒。与纯 Cu 或 Pd 金属相比，Pd 原子位上的氢易离解和与 Cu 的弱结合允许对苯乙烯和乙炔进行非常选择性的加氢。
