Excited State Dynamics in Dual-Defects Modified Graphitic Carbon Nitride

Area of Science:

• Materials Science
• Photocatalysis
• Surface Chemistry

Background:

• Graphitic carbon nitride (g-C3N4) is a promising metal-free photocatalyst.
• Defect engineering is crucial for enhancing g-C3N4's photocatalytic performance.
• Multidefect modification offers synergistic improvements over single defects.

Purpose of the Study:

• To model and compare excited state dynamics in g-C3N4 with single and dual defects.
• To investigate the role of nitrogen defects (N vacancy, CN group) and dual defects (N vacancy, CN group, O doping).
• To understand the mechanisms behind enhanced photocatalytic properties in defect-engineered g-C3N4.

Main Methods:

• Computational modeling of excited state dynamics.
• Analysis of charge carrier recombination mechanisms (Shockley-Read-Hall).
• Comparison of pristine and defect-engineered g-C3N4 systems.

Main Results:

• Nitrogen defects create midgap states acting as recombination centers.
• Dual-defect modified g-C3N4 exhibits superior properties due to facilitated charge separation and broader light absorption.
• Oxygen doping enhances carrier lifetime and oxidation potential via valence band downshifting.

Conclusions:

• Defect engineering, particularly multidefect modification, significantly enhances g-C3N4 photocatalysis.
• The presence and type of defects critically influence charge carrier dynamics and photocatalytic activity.
• This study provides a framework for designing advanced, efficient, and stable photocatalytic materials through rational defect engineering.