Kronberg Rasmus, Hakala Mikko, Holmberg Nico, Laasonen Kari
Research Group of Computational Chemistry, Department of Chemistry and Materials Science, Aalto University, P.O. Box 16100, FI-00076 Aalto, Finland.
Phys Chem Chem Phys. 2017 Jun 21;19(24):16231-16241. doi: 10.1039/c7cp03068a.
We report a comprehensive computational study of the intricate structure-property relationships governing the hydrogen adsorption trends on MoS edges with varying S- and H-coverages, as well as provide insights into the role of individual adsorption sites. Additionally, the effect of single- and dual S-vacancies in the basal plane on the adsorption energetics is assessed, likewise with an emphasis on the H-coverage dependency. The employed edge/site-selective approach reveals significant variations in the adsorption free energies, ranging between ∼±1.0 eV for the different edges-types and S-saturations, including differences of even as much as ∼1.2 eV between sites on the same edge. The incrementally increasing hydrogen coverage is seen to mainly weaken the adsorption, but intriguingly for certain configurations a stabilizing effect is also observed. The strengthened binding is seen to be coupled with significant surface restructuring, most notably the splitting of terminal S-dimers. Our work links the energetics of hydrogen adsorption on 2H-MoS to both static and dynamic geometrical features and quantifies the observed trends as a function of H-coverage, thus illustrating the complex structure/activity relationships of the MoS catalyst. The results of this systematical study aims to serve as guidance for experimentalists by suggesting feasible edge/S-coverage combinations, the synthesis of which would potentially yield the most optimally performing HER-catalysts.
我们报告了一项全面的计算研究，该研究涉及控制不同S和H覆盖率下MoS边缘氢吸附趋势的复杂结构-性质关系，并深入了解各个吸附位点的作用。此外，评估了基面中单S空位和双S空位对吸附能的影响，同样强调了对H覆盖率的依赖性。所采用的边缘/位点选择性方法揭示了吸附自由能的显著变化，不同边缘类型和S饱和度之间的变化范围约为±1.0 eV，同一边缘上的位点之间甚至存在高达约1.2 eV的差异。逐渐增加的氢覆盖率主要削弱吸附，但有趣的是，对于某些构型也观察到了稳定作用。增强的结合被认为与显著的表面重构有关，最明显的是末端S二聚体的分裂。我们的工作将2H-MoS上氢吸附的能量学与静态和动态几何特征联系起来，并将观察到的趋势量化为H覆盖率的函数，从而阐明了MoS催化剂复杂的结构/活性关系。这项系统研究的结果旨在为实验人员提供指导，建议可行的边缘/S覆盖率组合，合成这些组合可能会产生性能最优的析氢催化剂。
