Tailoring the work function of graphene via defects, nitrogen-doping and hydrogenation: A first principles study

Area of Science:

• Materials Science
• Condensed Matter Physics
• Computational Chemistry

Background:

• The work function of graphene is crucial for its electronic properties and applications.
• Understanding how defects and doping affect the work function is essential for material design.

Purpose of the Study:

• To investigate the impact of defects (Stone-Wales, vacancies), nitrogen doping (substitutional, pyridinic), and hydrogen saturation on graphene's work function using first-principles calculations.
• To elucidate the mechanisms behind these changes and reconcile theoretical findings with experimental observations.

Main Methods:

• First-principles calculations based on density functional theory (DFT).
• Simulation of various defect types, nitrogen doping configurations, and hydrogen saturation on graphene.

Main Results:

• Stone-Wales defects minimally affect the work function.
• Vacancy defects increase the work function by reducing π-electron density.
• Substitutional nitrogen doping decreases the work function due to electron donation.
• Pyridinic nitrogen doping at vacancies slightly increases the work function.
• Hydrogen saturation of pyridinic nitrogen shifts behavior towards graphitic, significantly reducing the work function.

Conclusions:

• The study provides a detailed atomistic understanding of how structural modifications and doping influence graphene's work function.
• Findings explain experimental results for carbon and nitrogen-doped materials.
• The work has significant implications for optimizing graphene in photocatalysis, photovoltaics, electrochemistry, and electron field emission devices.