In this paper, the mechanisms of H₂ evolution over the Mo-Edge of 2H-MoS₂ with the unsaturated Mo (Mo_U) and S (S_U) were investigated by the density functional theory. The calculations indicated that Mo_U was a key active site for H₂ evolution. In the process of H₂ evolution, the S_U firstly absorbed H atom by the Volmer reaction, which caused the aggregation of electron on Mo_U, resulting in the barriers reduction of H transfer and H₂ evolution on Mo_U. The formation of molybdenum hydride was the rate-limiting step. Compared to Mo-edge in 2H-MoS₂, the barrier of key step for H₂ evolution on Mo-edge with S_U and Mo_U decreased obviously. This implied that the removal fractional S from the Mo-edge of 2H-MoS₂ could enhance its H₂ evolution activity and the electron trapping ability of active site for H₂ evolution by the Volmer-Heyrovsky reaction might affect its activity.

本文通过密度泛函理论研究了H ₂在具有不饱和Mo（Mo _U）和S（S _U）的2H-MoS ₂的Mo-Edge上演化的机理。计算表明，Mo _U是H ₂析出的关键活性位点。在H ₂析出过程中，S _U首先通过Volmer反应吸收H原子，从而引起电子在Mo _U上聚集，从而减少了H迁移和Mo _U上H ₂析出的势垒。氢化钼的形成是限速步骤。与2H-MoS _2中的Mo-edge相比，S _U和Mo _U下Mo-edge上H ₂析出关键步骤的障碍明显减少。这暗示着从2H-MoS ₂的Mo边缘去除分数S可以增强其H _2的析出活性，而通过Volmer-Heyrovsky反应进行的H ₂析出的活性位点的电子俘获能力可能会影响其活性。