Self‐Passivated Metal Klein Edge of 1T‐Phase Transition Metal Dichalcogenides and the Induced High‐Efficient Hydrogen Evolution Reaction Activity

Abstract

The pristine edge of a 2D material generally undergoes an edge self‐passivation into its ground‐state configuration. To date, several self‐passivated edges of 1H‐phase transition metal dichalcogenides (TMDCs) have been reported in theories and experiments. However, no self‐passivated edges of its sister material 1T‐phase TMDCs are found. Here, taking 1T‐VS2 as an example, a self‐passivated V2 dimer‐like metal Klein (DM‐Klein) edge of 1T‐TMDCs is reported. It exhibits high thermodynamic stability and can spontaneously form at V‐rich chemical potential conditions. Unexpected intermetallic d–d orbital interaction of edge metal atoms results in metal dimerization. This edge self‐passivation mode is universal in group IV and V 1T‐TMDCs. Furthermore, strong intermetallic interaction and appropriate edge sulfur saturation make DM‐Klein edges of 1T‐TMDCs show excellent catalytic activity in the hydrogen evolution reaction compared to that of well‐known Pt(111) surface. This study provides opportunities for the further practical application of 1T‐TMDCs in catalysts.

Unconventional Self-Reconstructed Trimer-like Metal Zigzag Edge of 1T-Phase Transition Metal Dichalcogenides

“…Generally, the ZZ-50% X and ZZ-100% X edges easily reach the stable state through a slight bond contraction. In contrast, the ZZM edges with bare metal atoms remain energetically unfavorable after conventional slight bond contraction. − Here, we find a relatively drastic self-reconstructed pattern at the ZZM edge of 1T-TiTe 2 that is quite different from the slight bond contraction. As shown in panels a and b of Figure , the edge deformation is obvious during self-reconstruction from the as-cut ZZM edge to the Ti 3 trimer-like metal ZZ (called TMZ) edge.…”

“…As shown in Figure b, the E f of stoichiometric edge ZZ-50% Te is independent of Te chemical potential and remains low over a wide range of chemical potentials. This edge configuration has also been shown to have a high-energy advantage in other 1T-TMDCs such as 1T-VS 2 and 1T-PtSe 2 . , In contrast, the E f values of other nonstoichiometric edges are determined by Te chemical potential. The edge formation energy of the ZZ-100% Te edge gradually decreases under Te-rich conditions.…”

“…To better understand the synthesis conditions and the relative thermodynamic stability of the TMZ edge, we calculate a phase diagram with the edge formation energy (E f ) as a function of the Te chemical potential, including TMZ, as-cut ZZM, DM-Klein, 44 ZZ-50% Te, and ZZ-100% Te edges (Figure 2b). The thermodynamic stability of the edge is typically assessed via the edge formation energy, and a low E f means high thermodynamic stability (see the Supporting Information for calculation details).…”

“…This edge configuration has also been shown to have a high-energy advantage in other 1T-TMDCs such as 1T-VS 2 and 1T-PtSe 2 . 44,45 In contrast, the E f values of other nonstoichiometric edges are determined by Te chemical potential. The edge formation energy of the ZZ-100% Te edge gradually decreases under Te-rich conditions.…”

Theoretical Calculation Assisted by Machine Learning Accelerate Optimal Electrocatalyst Finding for Hydrogen Evolution Reaction

“…In this scenario, exploring economically and in a friendly manner with high-performance electrocatalysts for HER is urgent. Some alternative electrocatalysts, such as metal oxides, [7][8][9] MXene materials, [10][11][12] Transitional metal (TM) dichalcogenides, [13][14][15] Sn, Ge, Mo-based Phosphorus materials, [16,17] etc., exhibit better HER performance than Pt-based electrocatalysts. However, systematic investigation of a potential electrocatalyst from synthesis, modulation, and testing to application is time-consuming and energy dissipation.…”