Nair Akhil S, Anoop Anakuthil, Ahuja Rajeev, Pathak Biswarup
Department of Chemistry, Indian Institute of Technology Indore, Simrol, Indore, 453552, India.
Department of Chemistry, Indian Institute of Kharagpur, Kharagpur, West Bengal 721302, India.
J Phys Chem A. 2022 Mar 3;126(8):1345-1359. doi: 10.1021/acs.jpca.1c09981. Epub 2022 Feb 21.
Nanoclusters are materials of paramount catalytic importance. Among various unique properties featured by nanoclusters, a pronounced relativistic effect can be a decisive parameter in governing their catalytic activity. A concise study delineating the role of relativistic effects in nanocluster catalysis is carried by investigating the oxygen reduction reaction (ORR) activity of a Pt subnanometer cluster. Global optimization analysis shows the critical role of spin-orbit coupling (SOC) in regulating the relative stability between structural isomers of the cluster. An overall improved ORR adsorption energetics and differently scaled adsorption-induced structural changes are identified with SOC compared to a non-SOC scenario. atomistic thermodynamics analysis predicted nearly identical phase diagrams with significant structural differences for high coverage oxygenated clusters under realistic conditions. Though inclusion of SOC does not bring about drastic changes in the overall catalytic activity of the cluster, it is having a crucial role in governing the rate-determining step, transition-state configuration, and energetics of elementary reaction pathways. Furthermore, a statistical ensemble-based approach illustrates the strong contribution of low-energy local minimum structural isomers to the total ORR activity, which is significantly scaled up along the activity improving direction within the SOC framework. The study provides critical insights toward the importance of relativistic effects in determining various catalytic activity relevant features of nanoclusters.
纳米团簇是具有至关重要催化意义的材料。在纳米团簇所具有的各种独特性质中，显著的相对论效应可能是决定其催化活性的一个关键参数。通过研究铂亚纳米团簇的氧还原反应（ORR）活性，开展了一项关于相对论效应在纳米团簇催化中作用的简要研究。全局优化分析表明自旋轨道耦合（SOC）在调节团簇结构异构体之间的相对稳定性方面起着关键作用。与无SOC的情况相比，SOC使得ORR吸附能总体得到改善，并且吸附诱导的结构变化呈现出不同的尺度。原子热力学分析预测，在实际条件下，对于高覆盖度的含氧团簇，几乎相同的相图具有显著的结构差异。尽管纳入SOC并没有给团簇的整体催化活性带来剧烈变化，但它在控制速率决定步骤、过渡态构型以及基本反应途径的能量学方面起着关键作用。此外，基于统计系综的方法表明低能量局部极小值结构异构体对总ORR活性有很大贡献，在SOC框架内，沿着活性提高的方向，这种贡献显著增加。该研究为相对论效应在确定纳米团簇各种与催化活性相关特征方面的重要性提供了关键见解。
