Alkaline water electrolysis for green hydrogen production demands low-cost catalysts with accelerated kinetics. Here, we combine density functional theory (DFT) and ab initio molecular dynamics (AIMD) to investigate how sulfur vacancies (VS) and surface functionalization with Brønsted-acid end-capped aryl ligands (Ar–SO₃⁻ and Ar–COO⁻) modulate the hydrogen evolution reaction (HER) on 1T-MoS₂ nanosheets. We computed water adsorption energies, Volmer step barriers, and wettability metrics across stoichiometric, defective, and ligand-modified models. Key findings are: (i) pristine 1T-MoS₂ repels water due to S–H repulsion; (ii) VS dramatically enhances water adsorption by exposing Mo active sites; (iii) Ar–SO₃⁻ ligands create organic channels that steer H₂O toward vacancies and lower dissociation barriers relative to unmodified surfaces; (iv) AIMD confirms that 1T-MoS2@VS@Ar–SO₃⁻ systems exhibit improved hydrophilicity, whereas V_S+Ar–COO⁻ remains comparatively more hydrophobic. Experimental HER rates align with our predictions, underscoring that the synergistic interplay of vacancies and Brønsted-acid ligands establishes an optimal microenvironment for alkaline HER. These insights provide a surface-engineering strategy to design robust MoS₂-based catalysts with pH-independent performance in alkaline electrolytes.
Modeling of Engineered Molybdenum Sulfide for Hydrogen Evolution Reaction under Alkaline Conditions
Giuseppe Santoriello;Ida Ritacco;Giuliano Giambastiani;Lucia Caporaso
2025
Abstract
Alkaline water electrolysis for green hydrogen production demands low-cost catalysts with accelerated kinetics. Here, we combine density functional theory (DFT) and ab initio molecular dynamics (AIMD) to investigate how sulfur vacancies (VS) and surface functionalization with Brønsted-acid end-capped aryl ligands (Ar–SO₃⁻ and Ar–COO⁻) modulate the hydrogen evolution reaction (HER) on 1T-MoS₂ nanosheets. We computed water adsorption energies, Volmer step barriers, and wettability metrics across stoichiometric, defective, and ligand-modified models. Key findings are: (i) pristine 1T-MoS₂ repels water due to S–H repulsion; (ii) VS dramatically enhances water adsorption by exposing Mo active sites; (iii) Ar–SO₃⁻ ligands create organic channels that steer H₂O toward vacancies and lower dissociation barriers relative to unmodified surfaces; (iv) AIMD confirms that 1T-MoS2@VS@Ar–SO₃⁻ systems exhibit improved hydrophilicity, whereas V_S+Ar–COO⁻ remains comparatively more hydrophobic. Experimental HER rates align with our predictions, underscoring that the synergistic interplay of vacancies and Brønsted-acid ligands establishes an optimal microenvironment for alkaline HER. These insights provide a surface-engineering strategy to design robust MoS₂-based catalysts with pH-independent performance in alkaline electrolytes.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
