2H-MOS2 is one of the most promising electrocatalysts for hydrogen evolution (HER) without ***. A widely accepted view of its high-energy resonance mechanism is that its edge site has high high-energy resonance activity, while its base is inert during high-energy resonance.
Based on this,Professor Zhai Tianyou and Associate Professor Zhao Yinghe of Huazhong University of Science and Technology, Yang Fa of Zhejiang Normal University, etcBased on first-principles calculations, in situ atr-seiras spectroscopy and X-ray absorption fine structure measurements, the transient phase transition behavior of 2H-MOS2 was determined, and some basal surfaces of 2H-MOS2 exhibited high HER activity. During the HER reaction, MOS2 can undergo a local phase transition from the HER inert 2H phase to the 1T phase with high HER activity, and the phase transition is transient and returns to the 2H phase after the reaction.
The first step of the HER reaction is the Volmer step, which is denoted as *+H+ +E H*, where * denotes the catalytic site and H* denotes the intermediate with H ligands. The free energy change of the Volmer step is ΔGh, where ΔGh is widely used to reflect the HER activity of an electrocatalyst. The closer the ΔGH of the electrocatalyst is to 0 EV, the higher its HER activity. The δgh of the S atom on the surface of 2H-MOS2 is as high as 192 EV, extremely inert to HER. From a thermodynamic point of view, it takes about -2 to form a chemical bond between the h atom of 2H-MOS2 and the surface S atomPotential of 0 v.
When using ag@2h-MOS2 to catalyze HER, in-situ SERS measurements found that at a fairly low potential (-0.).2 v). A peak was observed at 2532 cm1 and attributed to the tensile vibration of the surface S-H bonds. Even when AG is considered, a fairly negative potential is still required to drive S-H bond formation on 2H-MOS2, which is in sharp contradiction with the experimental results and is not clear. For 2H-MOS2, a stay at -0 is observedAt 2 V, there is a peak around 2530 cm1. It is important to note that this peak does not originate from H adsorption at the edge.
transient phase transition during the hydrogen evolution reaction. energy environ. sci.,