Thermodynamically stable polymorphs of nitrogen-rich carbon nitrides: a C₃N₅ study

Area of Science:

• Materials Science
• Computational Chemistry
• Solid-State Physics

Background:

• Carbon nitride materials are investigated for diverse applications.
• Previous studies focused on graphite-like polymorphs for carbon nitrides.
• The stability of nitrogen-rich carbon nitrides remains an open question.

Purpose of the Study:

• To conduct an extensive search for stable polymorphs of carbon nitride with C3N5 stoichiometry.
• To challenge the prevailing assumption of graphite-like structures being the most stable.
• To discover novel carbon nitride morphologies and understand their formation.

Main Methods:

• Utilized the minima hopping method for an extensive search of stable polymorphs.
• Investigated the energy landscapes of nitrogen-rich carbon nitride compounds.
• Analyzed the structural characteristics and electronic properties of predicted structures.

Main Results:

• Identified novel, non-planar morphologies for C3N5 beyond graphite-like structures.
• Found that N-N bonds in nitrogen-rich materials favor diverse, non-graphitic structures.
• Discovered low-energy C3N5 structures with band gaps consistent with experimental data.

Conclusions:

• The stability of carbon nitrides is strongly dependent on nitrogen content and bonding.
• Novel morphologies of C3N5 emerge due to complex energy landscapes in nitrogen-rich systems.
• The predicted structures provide a basis for future experimental synthesis and validation.