Cheng Cheng, Zhang Xilin, Wang Mingyang, Wang Shiyan, Yang Zongxian
College of Physics and Materials Science, Henan Normal University, Xinxiang, Henan 453007, China.
Phys Chem Chem Phys. 2018 Jan 31;20(5):3504-3513. doi: 10.1039/c7cp07161b.
The geometric stability, electronic structure and catalytic properties of a single Pd atom deposited on a pristine MoCO monolayer and a defective MoCO monolayer with an oxygen vacancy (denoted as Pd/O-MoCO) are systematically investigated through density functional theory. We find that the oxygen vacancy (O) can stabilize the single Pd atom and make the Pd/O-MoCO system an excellent mono-dispersed atomic catalyst. The Pd dopant serves as an active center which makes the intermediates react productively around it. Three reaction mechanisms are considered for CO oxidation to test the catalytic activity of Pd/O-MoCO, which exhibits high activity for CO oxidation via a tri-molecular Eley-Rideal (TER) mechanism with a rate-limiting energy barrier of 0.49 eV. The pre-adsorbed CO molecules on the Pd dopant could transfer electrons to the O-2π* orbitals, which would promote O molecule activation and induce O-O bond scission. This work demonstrates that the defective monolayer MXene may serve as a promising sort of support to fabricate single atomic catalysts (SACs) for CO oxidation or other reactions, agreeing well with the experimental reports, which opens up a new avenue for the design and fabrication of SACs of MXene-based materials.
通过密度泛函理论系统地研究了沉积在原始MoCO单层和具有氧空位的缺陷MoCO单层（表示为Pd/O-MoCO）上的单个Pd原子的几何稳定性、电子结构和催化性能。我们发现氧空位（O）可以稳定单个Pd原子，并使Pd/O-MoCO体系成为一种优异的单分散原子催化剂。Pd掺杂剂作为活性中心，使中间体在其周围发生有效反应。考虑了三种CO氧化反应机制来测试Pd/O-MoCO的催化活性，其通过三分子Eley-Rideal（TER）机制对CO氧化表现出高活性，限速能垒为0.49 eV。Pd掺杂剂上预先吸附的CO分子可以将电子转移到O的2π*轨道，这将促进O分子的活化并诱导O-O键断裂。这项工作表明，缺陷单层MXene可能是一种有前途的载体，可用于制备用于CO氧化或其他反应的单原子催化剂（SAC），这与实验报告非常吻合，为基于MXene的材料的SAC的设计和制备开辟了一条新途径。
