Defect and strain engineered MoS₂/graphene catalyst for an enhanced hydrogen evolution reaction.

Area of Science:

• Materials Science
• Electrochemistry
• Computational Chemistry

Background:

• Molybdenum disulfide (MoS2) is a promising non-precious metal electrocatalyst for the hydrogen evolution reaction (HER).
• However, its efficiency is limited by inert basal planes and poor electrical conductivity.

Purpose of the Study:

• To investigate strategies for activating the MoS2 basal plane and enhancing HER activity.
• To explore the combined effects of intrinsic defects and strain engineering on MoS2/graphene hybrids.

Main Methods:

• Density functional theory (DFT) calculations were employed.
• Seven types of point defects in MoS2/graphene were analyzed.
• Hydrogen adsorption free energy (ΔGH) was used as a descriptor, along with tensile strain engineering.

Main Results:

• Four out of seven investigated defects (VS, VS2, MoS2, VMoS3) were identified as active sites for HER.
• Tensile strain was found to tune ΔGH to an ideal value (0 eV), boosting HER activity, particularly for specific defects.
• The d-band center of metals effectively described H adsorption strength under strain.

Conclusions:

• Combining tensile strain and defect engineering is an effective strategy to enhance HER performance.
• Defective MoS2/graphene systems exhibit favorable kinetics for H2 evolution via Volmer-Heyrovsky and Volmer-Tafel mechanisms.
• This study provides a pathway for designing advanced MoS2-based HER catalysts.