Nitrogen clusters inside C60 cage and new nanoscale energetic materials

TL;DR

This study investigates encapsulating nitrogen clusters inside C60 fullerenes, revealing stable structures with potential for high-energy materials, and identifies the maximum nitrogen content and energetic release potential.

Contribution

It introduces the concept of trapping polynitrogen clusters inside C60 cages and characterizes their stability and electronic properties, a novel approach for nitrogen-rich energetic materials.

Findings

Maximum of 13 nitrogen atoms encapsulated in C60.

Nitrogen clusters exhibit stable polymeric structures with predominant single bonds.

Clusters can release significant energy upon relaxation to N2 molecules.

Abstract

We explore the possibility to trap polynitrogen clusters inside C60 fullerene cage, opening a new direction of developing nitrogen-rich high energy materials. We found that a maximum of 13 nitrogen atoms can be encapsulated in a C60 cage. The nitrogen clusters in confinement exhibit unique stable structures in polymeric form which possess a large component of (~ 70-80%) single bond character. The Nn@C60 molecules retain their structure at 300K for n<12. The Mulliken charge analysis shows very small charge transfer in N@C60, consistent with the quartet spin state of N. However, for 2<n<10, charge transfer take place from cage surface to Nn compounds and inverse polarization thereafter. These nitrogen clusters when allowed to relax to N2 molecules which are triply bonded are capable of releasing a large amount of energy.