Combined DFT-D3 Computational and Experimental Studies on g-C₃N₄: New Insight into Structure, Optical, and...

Area of Science:

• Materials Science
• Photocatalysis
• Polymer Chemistry

Background:

• Graphitic carbon nitride (g-C3N4) is a promising metal-free semiconductor photocatalyst with good stability.
• Its photocatalytic efficiency is hindered by low surface area and rapid charge recombination.
• Current research focuses on improving synthesis methods to overcome these limitations.

Purpose of the Study:

• To elucidate the precise structure of polymerized carbon nitride materials derived from melamine.
• To understand the nature of these structures for enhanced photocatalytic applications.
• To bridge the knowledge gap regarding pristine g-C3N4.

Main Methods:

• Combined experimental techniques: X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), UV-Visible spectroscopy, and Fourier-Transform Infrared (FTIR) spectroscopy.
• Theoretical calculations using Density Functional Theory (DFT).
• Analysis of melamine heated under mild conditions.

Main Results:

• Calculated an indirect band gap for the material.
• Identified characteristic vibrational peaks.
• Revealed a composite structure comprising highly condensed g-C3N4 domains within a less condensed, 'melon-like' framework.

Conclusions:

• The study provides a comprehensive understanding of the structure of polymerized carbon nitrides synthesized from melamine.
• The findings highlight a heterogeneous structure, crucial for optimizing photocatalytic performance.
• This detailed structural insight aids in the rational design of advanced g-C3N4-based materials.