P1-C₇N₄O₈: improved stability and energy density via a covalent framework with uniform single bonds

Area of Science:

• Materials Science
• Chemistry
• Computational Chemistry

Background:

• Energetic materials store energy in chemical bonds.
• Non-uniform bonds in CNO materials create a trade-off between stability and energy density.
• Strong bonds reduce energy density, while weak bonds lower stability.

Purpose of the Study:

• To design a novel energetic material with uniform chemical bonds.
• To achieve a balance between structural stability and high energy density.
• To explore a 3D close-packed structure for energetic materials.

Main Methods:

• First-principles crystal structure search.
• Thermodynamic analysis of material formation.
• Density Functional Theory (DFT) calculations.

Main Results:

• A stable 3D close-packed structure, P1-C7N4O8, with uniform C-N and C-O single bonds was identified.
• P1-C7N4O8 is thermodynamically favorable at 31 GPa, formed from C3N4 and CO2.
• The material exhibits high mass density (3.08 g cm⁻³) and volumetric energy density (18.12 kJ cm⁻³) at ambient conditions.
• Elongated C-N and C-O bonds upon decompression enhance energy density.

Conclusions:

• A 3D covalent structure with uniform single bonds is key for stable, high-performance energetic materials.
• P1-C7N4O8 surpasses existing CHON and CxNyOz energetic materials in density and energy storage.
• This research opens new avenues for designing advanced energetic materials.