Fabila J, Romero D, Paz-Borbón O, Buendía F
Instituto de Física, Universidad Nacional Autónoma de México, Apartado Postal 20-364, 01000 Mexico City, Mexico.
J Chem Phys. 2022 Aug 28;157(8):084309. doi: 10.1063/5.0100739.
A comprehensive computational study on the oxygen molecule (O) adsorption and activation on bimetallic Au-Ir subnanometer clusters supported on TiO(101)- up to five atoms in size-is performed. A global optimization density functional theory-based basin-hopping algorithm is used to determine putative global minima configurations of both mono- and bimetallic clusters supported on the metal oxide surface for all sizes and compositions. Our results indicate a strong cluster-oxide interaction for monometallic Ir clusters with calculated adsorption energy (E) values ranging from -3.11 to -5.91 eV. Similar values are calculated for bimetallic Au-Ir clusters (-3.21 up to -5.69 eV). However, weaker E values are calculated for Au clusters (ranging from -0.66 to -2.07 eV). As a general trend, we demonstrate that for supported Au-Ir clusters on TiO(101), those Ir atoms preferentially occupy cluster-oxide interface positions while acting as anchor sites for the Au atoms. The overall geometric arrangements of the putative global minima configurations define O adsorption and dissociation, particularly involving the monometallic Au and Ir as well as the bimetallic AuIr and AuIr supported clusters. Spontaneous O dissociation is observed on both Ir and on the Ir-metallic part of AuIr and AuIr supported clusters. This is in sharp contrast with supported Au, where a large activation energy is needed (1.90 eV). Interestingly, for Au, we observe that molecular O adsorption is favorable at the cluster/oxide interface, followed by a smaller dissociation barrier (0.71 eV). From a single cluster catalysis point of view, our results have strong implications in the ongoing understanding of oxide supported bimetallic while providing a useful first insight into the continuous in silico design of novel subnanometer catalysts.
对负载在TiO(101)上尺寸达五个原子的双金属Au-Ir亚纳米团簇上氧分子（O）的吸附和活化进行了全面的计算研究。基于全局优化密度泛函理论的盆地跳跃算法用于确定金属氧化物表面上负载的单金属和双金属团簇在所有尺寸和组成下的假定全局极小值构型。我们的结果表明，单金属Ir团簇与氧化物之间存在很强的团簇-氧化物相互作用，计算得到的吸附能（E）值在-3.11至-5.91 eV范围内。双金属Au-Ir团簇的计算值类似（-3.21至-5.69 eV）。然而，Au团簇的E值较弱（范围为-0.66至-2.07 eV）。作为一般趋势，我们证明，对于负载在TiO(101)上的Au-Ir团簇，那些Ir原子优先占据团簇-氧化物界面位置，同时作为Au原子的锚定位点。假定全局极小值构型的整体几何排列决定了O的吸附和解离，特别是涉及单金属Au和Ir以及双金属AuIr和AuIr负载团簇。在Ir以及AuIr和AuIr负载团簇的Ir金属部分都观察到了自发的O解离。这与负载的Au形成鲜明对比，负载的Au需要很大的活化能（1.90 eV）。有趣的是，对于Au，我们观察到分子O在团簇/氧化物界面的吸附是有利的，随后是较小的解离势垒（0.71 eV）。从单团簇催化的角度来看，我们的结果对正在进行的氧化物负载双金属的理解有重要意义，同时为新型亚纳米催化剂的连续计算机辅助设计提供了有用的初步见解。
