Defect engineering is a common and promising strategy to improve the catalytic activity of layered structures such as MoS₂, where in particular the 2H and 1T′ polymorphs have been under intense study for their activity toward the hydrogen evolution reaction. However, the large variety of defects, each with its own distinct and usually unknown effects, complicates the design and optimization of such defective materials. Therefore, it is relevant to characterize in detail the effect of individual defects and to be able to combine these observations to describe more complex materials, such as those seen experimentally. Therefore, nine point defects (antisites defects and vacancies) are theoretically studied on single layer 1T, 1T′, and 2H MoS₂ polymorphs, and the variation and spatial distribution in the active sites are identified. It is found that all defective 1T′ monolayers exhibit an increase in the exchange current density of at least 2.3 times when compared to pristine 1T′ MoS₂, even if a reduced number of active sites are observed. The results are later used to propose a methodology to study materials containing a mixture of crystal phases, or other alterations that cause inhomogeneous changes in the activity of catalytic sites.

中文翻译：

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缺陷2H和1T'MoS2多晶型物用于氢析出反应的表面活性位点的理论分析：量化点缺陷的总活性

缺陷工程学是改善诸如MoS _2之类的层状结构的催化活性的常见且有希望的策略，其中特别是2H和1T'多晶型物对氢释放反应的活性已受到广泛研究。然而，各种各样的缺陷，每个缺陷都有其自己独特的，通常是未知的影响，使这种缺陷材料的设计和优化变得复杂。因此，重要的是要详细描述单个缺陷的影响，并能够将这些观察结果结合起来描述更复杂的材料，例如通过实验观察到的材料。因此，理论上在单层1T，1T'和2H MoS ₂上研究了九个点缺陷（反位缺陷和空位）多态性，并确定了活动位点的变化和空间分布。发现与原始1T'MoS ₂相比，所有有缺陷的1T'单层都表现出至少2.3倍的交换电流密度增加，即使观察到活性位点数量减少。后来的结果被用来提出一种研究包含晶相混合物或其他引起催化位点活性不均匀变化的改变的材料的方法。