Optimizing the Surface Coordination of Pd-Cu Nanoalloy Through Chemical Ordering to Enhance Hydrogenation Selectivity

en This link goes to a English section zh This link goes to a Chinese section Precise control of chemical ordering in bimetallic nanocatalysts offers a route to decouple activity and selectivity in acetylene hydrogenation, but direct atomic-scale evidence linking surface order to catalytic performance is scarce. Here, we tune Pd-Cu nanoalloys from chemically disordered to highly ordered states by composition control and targeted H 2 thermal treatment. Under near-industrial conditions, all catalysts reach full acetylene conversion between 100°C and 120°C, whereas the ethylene selectivity enhances with the chemical ordering increasing. By combining synchrotron X-ray absorption fine structure (XAFS) with X-ray total scattering and reverse Monte Carlo (RMC) simulation, three-dimensional atomic models are reconstructed to quantitatively map surface coordination. Compared with the chemically disordered Pd-Cu nanocatalyst, the highly ordered PdCu shows an increase in average surface Pd-Cu coordination and an expansion of mean surface Pd-Pd separations. These structural features weaken ethylene binding and suppress re-adsorption, rationalizing the enhanced selectivity. Our study provides direct atomic-scale evidence connecting chemical order to catalytic selectivity and opens the way for guiding the precise design of bimetal nanocatalysts. 摘要 en This link goes to a English section zh This link goes to a Chinese section 精准调控双金属纳米催化剂的化学有序,可为乙炔加氢反应中活性与选择性的解耦提供有效路径。然而将表面有序度与催化性能直接关联的原子尺度证据仍较为缺乏。本研究通过成分调控与氢气热处理,成功实现了Pd-Cu纳米合金从化学无序态到高度有序态的转变。在近工业条件下,所有催化剂均在100–120°C区间内实现乙炔完全转化,而乙烯选择性随化学有序度的提升显著增强。结合同步辐射X射线吸收精细结构谱、X射线全散射及反向蒙特卡洛(RMC)模拟,我们重构了纳米合金的三维原子结构模型,实现了表面配位环境的定量解析。与化学无序的Pd-Cu纳米催化剂相比,高度有序的PdCu合金表现出更高的表面Pd–Cu配位数和更长的平均Pd–Pd键距。这些结构特征有助于弱化乙烯吸附并提高其选择性。本研究为化学有序与乙烯选择性之间的关联提供了直接的原子尺度证据,为双金属纳米催化剂的精准设计开辟了新途径。