Closed Reconstructed Edges of Bilayer H‐MoS₂

Abstract Edge reconstruction in monolayer 2D materials has received extensive attention owing to its potential applications in electronics, catalysis, and nanomaterial design. However, research on the reconstructed edges of bilayer 2D materials, particularly transition metal dichalcogenides (TMDCs), remains limited. Bilayer TMDCs, with unique interlayer interactions, may exhibit novel edge properties, making them promising for catalytic applications. Here, bilayer H‐MoS 2 is used as a model system to investigate how the chemical environment influences the reconstructed edges in 2D TMDCs through first‐principles calculations. The results show that the closed reconstructed edge is the most stable configuration, exhibiting high thermodynamic stability under molybdenum‐rich concentrations and low sulfur chemical potentials. The closed reconstructed edges can reduce the band gap of bulk bilayer H‐MoS 2 . These closed reconstructed edges also increase the specific surface area and density of states at the Fermi level, increasing the catalytic activity for the hydrogen evolution reaction (HER) and achieving a hydrogen adsorption Gibbs free energy (|Δ G H |) of 0.073 eV. This value is significantly closer to the ideal value of zero than that of Pt(111) (|Δ G H | = 0.168 eV), indicating superior HER performance. This study provides insights for cost‐effective, high‐performance alternatives to Pt‐based catalysts in energy applications.