Two-dimensional Janus B2P6 as potential gas sensors for NO and NO2 detection: A first-principles study

The adsorption properties of novel Janus B2P6 nanosheet with NO and NO2 on both sides are researched by DFT calculation. The results show that the (001) surface exhibits moderate adsorption energies of −0.38 eV for NO and −0.42 eV for NO2. It is found that the electronic properties of Janus B2P6 are affected obviously by NO2 adsorption on the (001) surface, where the bandgap energy is decreased by 1.14 eV and the magnetic moment of 0.93 μB is induced, indicating Janus B2P6 exhibits better sensitivity to NO2. Note that the recovery times of NO and NO2 are found to be 2.4 and 11.0 μs, facilitating the reuse of devices. And a large diffusion energy barrier is found to ensure the stable transmission of signal. Moreover, under biaxial strain of −2%, the adsorption energy of NO on the (001) surface is greatly reduced to −0.24 eV, favoring the desorption of gas molecules. Verifiably, the combined variation of the electrostatic potential difference and the bonding environment leads to differences in the adsorption behavior. These findings demonstrate the potential of Janus B2P6 as ultra-sensitive strain gas sensors.