  Black phosphorus nitrogen (BP-N) is an attractive high-energy-density
material. However, high-pressure synthesized BP-N will decompose at
low-pressure and cannot be quenched to ambient conditions. Finding a method to
stabilize it at 0 GPa is of great significance for its practical applications.
However, unlike cg-N, LP-N, and HLP-N, it is always a metastable phase at
high-pressure up to 260 GPa, and decomposes into chains at 23 GPa. Here, based
on the first-principles simulations, we find that P atom doping can effectively
reduce the synthesis pressure of BP-N and maintain its stability at 0 GPa.
Uniform distribution of P atom dopants within the layer helps maintain the
structural stability of BP-N layer at 0 GPa, while interlayer electrostatic
interaction induced by N-P dipoles enhances its dynamic stability by
eliminating interlayer slipping. Furthermore, pressure is conducive to
enhancing the stability of BP-N and its doped forms by suppressing N-chain
dissociation. For the configuration with 12.5% doping concentration, a
gravimetric energy density of 8.07 kJ/g can be realized, which is nearly two
times higher than TNT.
