Farigliano Lucas M, Paredes-Olivera Patricia A, Patrito Eduardo M
Departamento de Fisicoquímica, Instituto de Investigaciones en Físico Química de Córdoba (INFIQC), Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, X5000HUA Córdoba, Argentina.
Departamento de Química Teórica y Computacional, Instituto de Investigaciones en Físico Química de Córdoba (INFIQC), Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, X5000HUA Córdoba, Argentina.
Phys Chem Chem Phys. 2021 May 5;23(17):10225-10235. doi: 10.1039/d0cp06502a.
The reactions of O2 with S vacancy sites within a MoS2 monolayer were investigated using density functional theory calculations. We considered the following defects: single S vacancy, double S vacancy, two adjacent S vacancies and two S vacancies separated by a sulphur atom. We found that the surface distribution of S vacancy sites plays a key role in determining the surface reactivity towards O2. We observed the desorption of SO2 only for the last vacancy distribution. For the other cases, the surface becomes passivated with very stable structures having O atoms on the original vacancy sites and in some cases an SO group in an adjacent position. The ab initio molecular dynamics simulations showed that the impingement of the O2 molecule on an S vacancy site produces a stable chemisorbed O2 molecule with an upright configuration. The surface reactions initiate after the O2 molecule switches to the lying-down configuration which favours the breakage of the O-O bond and the concurrent formation of S-O bonds. In the most reactive vacancy site configuration, the dissociation of the first O2 molecule produces an SO intermediate which finally leads to desorption of SO2 after oxygen abstraction from the other adjacent O2 molecule. The formation of a MoO3 moiety within the monolayer was also observed in the molecular dynamic simulations at higher oxidation levels.
使用密度泛函理论计算研究了O₂与MoS₂单层内硫空位的反应。我们考虑了以下缺陷：单硫空位、双硫空位、两个相邻硫空位以及被一个硫原子隔开的两个硫空位。我们发现硫空位的表面分布在决定对O₂的表面反应性方面起着关键作用。仅在最后一种空位分布情况下观察到SO₂的解吸。对于其他情况，表面被钝化，形成非常稳定的结构，原始空位处有O原子，在某些情况下相邻位置还有一个SO基团。从头算分子动力学模拟表明，O₂分子撞击硫空位会产生一个呈直立构型的稳定化学吸附O₂分子。当O₂分子转变为平躺构型时，表面反应开始，平躺构型有利于O - O键的断裂以及同时形成S - O键。在最具反应性的空位构型中，第一个O₂分子的解离产生一个SO中间体，该中间体最终在从另一个相邻O₂分子夺取氧后导致SO₂解吸。在更高氧化水平的分子动力学模拟中还观察到单层内形成了MoO₃部分。
