First-principles study on enhancing the photocatalytic hydrogen evolution performance in Cs₃Bi₂I₉/MoS₂...

Area of Science:

• Materials Science
• Energy Science
• Photocatalysis

Background:

• Hydrogen is a promising clean energy source.
• Developing efficient photocatalysts for hydrogen evolution is crucial for replacing fossil fuels.
• Bismuth-based halide perovskites and transition metal dichalcogenides are potential candidates for photocatalysis.

Purpose of the Study:

• To investigate the structural, electronic, and optical properties of Cs3Bi2I9/MoS2 heterostructures for photocatalytic hydrogen evolution.
• To identify the most promising heterostructure configuration for efficient hydrogen production.
• To understand the role of vacancy defects in enhancing photocatalytic activity.

Main Methods:

• First-principles calculations were employed to study the properties of Cs3Bi2I9/MoS2 heterostructures.
• The stability, electronic band structure, and optical properties were analyzed.
• The Gibbs free energy of hydrogen adsorption was calculated to assess photocatalytic potential.

Main Results:

• Cs3Bi2I9/MoS2 heterostructures are energetically stable and exhibit an interfacial dipole moment that suppresses charge carrier recombination.
• A heterostructure with a cesium vacancy (V_Cs) at the interface demonstrated the most favorable band-edge alignment and hydrogen adsorption energy.
• The V_Cs defect formation is favored under specific conditions (I-rich/Cs-poor) while suppressing other vacancy formations.

Conclusions:

• The Cs3Bi2I9/MoS2 heterostructure with an interfacial V_Cs defect is a highly promising material for photocatalytic hydrogen evolution.
• This work offers a pathway for designing advanced photocatalysts using Bi-based halide perovskites and transition metal dichalcogenides.
• The findings contribute to the development of solar-driven water splitting technologies for sustainable hydrogen production.