High-nitrogen-content energetic BN ( = 4-16) clusters.

Nitrogen-rich materials have attracted considerable attention in recent years as potential high-energy-density materials (HEDMs). However, their metastability poses substantial challenges for synthesis under ambient conditions. Here, we employ a novel strategy to explore energetic and structural features of the nitrogen-rich BN ( = 4-16) clusters by doping with the light non-metal boron. A series of boron-doped nitrogen clusters, with nitrogen content ranging from 83% to 96%, were obtained by laser ablation and analyzed time-of-flight mass spectrometry. The results indicate that the BN cluster is dominant in the mass spectrum, while the BN cluster exhibits the highest abundance after cooling the cluster source with liquid nitrogen. To further confirm the experimental results, extensive structure searches for BN ( = 4-16) clusters are conducted using the CALYPSO method and density functional theory (DFT) calculations. The calculations show that BN (singlet) exhibits a planar [B(NN)] three-branched geometry with symmetry, while BN (singlet) adopts a [(linear-N)B(N)] branched geometry with symmetry. Stability analyses reveal the relatively high structural stabilities of BN and BN clusters and agree well with the experimental findings. Notably, the gas-phase enthalpy of formation of the BN cluster is remarkably high, -1385.10 kJ mol, suggesting its potential as a high-energy building block for HEDM construction. The present findings enhance the structural diversities of non-metal-doped nitrogen clusters, and offer new perspectives for the rational design and synthesis of nitrogen-rich energetic materials.