Mohrhusen Lars, Zhang Shengjie, Montemore Matthew M, Madix Robert J
Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, 02138, USA.
Department of Chemical and Biomolecular Engineering, Tulane University, New Orleans, LA, 70118, USA.
Small. 2024 Nov;20(48):e2405715. doi: 10.1002/smll.202405715. Epub 2024 Sep 6.
Improving control over active-site reactivity is a grand challenge in catalysis. Single-atom alloys (SAAs) consisting of a reactive component doped as single atoms into a more inert host metal feature localized and well-defined active sites, but fine tuning their properties is challenging. Here, a framework is developed for tuning single-atom site reactivity by alloying in an additional inert metal, which this work terms an alloy-host SAA. Specifically, this work creates about 5% Pd single-atom sites in a PdAg(111) single crystal surface, and then identifies Sn based on computational screening as a suitable third metal to introduce. Subsequent experimental studies show that introducing Sn indeed modifies the electronic structure and chemical reactivity (measured by CO desorption energies) of the Pd sites. The modifications to both the electronic structure and the CO adsorption energies are in close agreement with the calculations. These results indicate that the use of an alloy host environment to modify the reactivity of single-atom sites can allow fine-tuning of catalytic performance and boost resistance against strong-binding adsorbates such as CO.
增强对活性位点反应性的控制是催化领域的一项重大挑战。单原子合金（SAA）由作为单原子掺杂到更惰性主体金属中的活性成分组成，具有局部化且明确的活性位点，但对其性质进行微调具有挑战性。在此，开发了一种通过在其中合金化额外的惰性金属来调节单原子位点反应性的框架，这项工作将其称为合金主体SAA。具体而言，这项工作在PdAg(111)单晶表面创建了约5%的钯单原子位点，然后通过计算筛选确定锡是合适的第三种引入金属。随后的实验研究表明，引入锡确实改变了钯位点的电子结构和化学反应性（通过CO脱附能测量）。对电子结构和CO吸附能的改变与计算结果高度吻合。这些结果表明，利用合金主体环境来改变单原子位点的反应性可以实现对催化性能的微调，并提高对诸如CO等强结合吸附质的抗性。
