Cerium-promoted conversion of dinitrogen into high-energy-density material CeN₆ under moderate pressure

Synthesis pressure and structural stability are two crucial factors for highly energetic materials, and recent investigations have indicated that cerium is an efficient catalyst for N-2 reduction reactions. Here, we systematically explore Ce-N compounds through first-principles calculations, demonstrating that the cerium atom can weaken the strength of the N=N bond and that a rich variety of cerium polynitrides can be formed under moderate pressure. Significantly, P1-CeN6 possesses the lowest synthesis pressure of 32 GPa among layered metal polynitrides owing to the strong ligand effect of cerium. The layered structure of P1-CeN6 proposed here consists of novel N-14 ring. To clarify the formation mechanism of P1-CeN6, the reaction path Ce + 3N(2) ? trans-CeN6 ? P1-CeN6 is proposed. In addition, P1-CeN6 possesses high hardness (20.73 GPa) and can be quenched to ambient conditions. Charge transfer between cerium atoms and N-14 rings plays a crucial role in structural stability. Furthermore, the volumetric energy density (11.20 kJ/cm(3)) of P1-CeN6 is much larger than that of TNT (7.05 kJ/cm(3)), and its detonation pressure (128.95 GPa) and detonation velocity (13.60 km/s) are respectively about seven times and twice those of TNT, and it is therefore a promising high-energy-density material.