Chen Yan, Deng Jia-Jun, Yao Wen-Wen, Gurti Joseph Israel, Li Wei, Wang Wen-Jie, Yao Jian-Xi, Ding Xun-Lei
School of Mathematics and Physics, North China Electric Power University, Beinong Road 2, Huilongguan, Beijing 102206, P. R. China.
Phys Chem Chem Phys. 2021 Jan 6;23(1):347-355. doi: 10.1039/d0cp04457a.
Structures of non-stoichiometric MoxSy clusters (x = 2-4; y = 2-10) were studied by density functional calculations with global optimization. Besides 1T phase like structures, a novel regular grid structure in which Mo atoms are well separated by S atoms was found, which might be used as a building-block to construct a new type of two-dimensional molybdenum sulfide monolayer. The hydrogen molecule prefers to be adsorbed onto Mo atoms rather than S atoms, and Mo atoms with less S coordination have a higher ability to adsorb H2. In addition, the reaction pathways for H2 dissociation were studied on two clusters with the highest H2 adsorption energy (Mo2S4 and Mo3S3). The vacant bridge site of Mo-Mo in S-deficient clusters, which corresponds to the sulfur vacancy in the bulk phase MoS2, is favored by H atom adsorption and plays an important role in the H atom transfer on MoxSy clusters. Our results provide a new aspect to understand the reason why S defect in MoS2 and MoS2 with an Mo-edge could enhance the catalytic performance in the hydrogen evolution reaction.
通过全局优化的密度泛函计算研究了非化学计量比的MoxSy团簇（x = 2 - 4；y = 2 - 10）的结构。除了类似1T相的结构外，还发现了一种新型的规则网格结构，其中Mo原子被S原子很好地隔开，这可能用作构建新型二维硫化钼单层的基础单元。氢分子更倾向于吸附在Mo原子上而不是S原子上，且S配位较少的Mo原子具有更高的吸附H2的能力。此外，在具有最高H2吸附能的两个团簇（Mo2S4和Mo3S3）上研究了H2解离的反应途径。缺硫团簇中Mo - Mo的空桥位，对应于体相MoS2中的硫空位，有利于H原子吸附，并在MoxSy团簇上的H原子转移中起重要作用。我们的结果为理解MoS2中的S缺陷以及具有Mo边缘的MoS2为何能增强析氢反应的催化性能提供了一个新的视角。
