Department of Chemistry, Tufts University, Medford, Massachusetts 02155, United States.
Department of Chemical Engineering, University College London, London WC1E 7JE, U.K.
J Phys Chem Lett. 2022 Jul 14;13(27):6316-6322. doi: 10.1021/acs.jpclett.2c01596. Epub 2022 Jul 6.
Dicarbonyl species are ubiquitous on Rh/oxide catalysts and are known to form on Rh centers. However, dicarbonyl species have never been directly observed on single-atom alloys (SAAs) where the active site is metallic. Herein, using surface science and theoretical modeling, we provide evidence of dicarbonyl species at isolated Rh sites on a RhCu(100) SAA. This approach not only enables us to directly visualize dicarbonyl species at Rh sites but also demonstrates that the transition between the mono- and dicarbonyl configuration can be achieved by changing surface temperature and CO pressure. Density functional theory calculations further support the mono- and dicarbonyl assignments and provide evidence that these species should be stable on other SAA combinations. Together, these results provide a picture of the structure and energetics of both the mono- and dicarbonyl configurations on the RhCu(100) SAA surface and should aid with IR assignments on SAA nanoparticle catalysts.
二羰基物种在 Rh/氧化物催化剂上普遍存在，已知在 Rh 中心形成。然而，二羰基物种从未在单原子合金 (SAA) 上直接观察到，因为单原子合金的活性位点是金属的。在此，我们使用表面科学和理论建模，提供了在 RhCu(100) SAA 上孤立 Rh 位点上二羰基物种的证据。这种方法不仅使我们能够直接观察 Rh 位点上的二羰基物种，还证明通过改变表面温度和 CO 压力可以实现单羰基和二羰基构型之间的转变。密度泛函理论计算进一步支持了单羰基和二羰基的分配，并提供了这些物种在其他 SAA 组合上应该稳定的证据。总的来说，这些结果提供了 RhCu(100) SAA 表面上单羰基和二羰基构型的结构和能量的图片，并应该有助于 SAA 纳米粒子催化剂上的 IR 分配。
