Department of Chemistry, Tsinghua University , Beijing 100084, China.
Shanghai Synchrontron Radiation Facility, Shanghai Institute of Applied Physics, Chinese Academy of Sciences , Shanghai 201204, China.
J Am Chem Soc. 2017 May 31;139(21):7294-7301. doi: 10.1021/jacs.7b01471. Epub 2017 May 22.
Improving the catalytic selectivity of Pd catalysts is of key importance for various industrial processes and remains a challenge so far. Given the unique properties of single-atom catalysts, isolating contiguous Pd atoms into a single-Pd site with another metal to form intermetallic structures is an effective way to endow Pd with high catalytic selectivity and to stabilize the single site with the intermetallic structures. Based on density functional theory modeling, we demonstrate that the (110) surface of Pm3̅m PdIn with single-atom Pd sites shows high selectivity for semihydrogenation of acetylene, whereas the (111) surface of P4/mmm PdIn with Pd trimer sites shows low selectivity. This idea has been further validated by experimental results that intermetallic PdIn nanocrystals mainly exposing the (110) surface exhibit much higher selectivity for acetylene hydrogenation than PdIn nanocrystals mainly exposing the (111) surface (92% vs 21% ethylene selectivity at 90 °C). This work provides insight for rational design of bimetallic metal catalysts with specific catalytic properties.
提高 Pd 催化剂的催化选择性对于各种工业过程至关重要，但迄今为止仍然是一个挑战。鉴于单原子催化剂的独特性质，将相邻的 Pd 原子隔离到具有另一种金属的单个 Pd 位中以形成金属间结构是赋予 Pd 高催化选择性并稳定具有金属间结构的单原子的有效方法。基于密度泛函理论建模，我们证明了具有单原子 Pd 位的 Pm3̅m PdIn(110)表面对于乙炔的半氢化具有高选择性，而具有 Pd 三聚体位的 P4/mmm PdIn(111)表面则具有低选择性。这一观点通过实验结果得到了进一步验证，即主要暴露(110)表面的金属间 PdIn 纳米晶对于乙炔加氢的选择性要比主要暴露(111)表面的 PdIn 纳米晶高得多（在 90°C 时，乙烯选择性分别为 92%和 21%）。这项工作为具有特定催化性能的双金属金属催化剂的合理设计提供了思路。
