Impact of N‐Doping on MoSe₂ Monolayer for PH₃, C₂N_2, and HN₃ Gas Sensing: A DFT Study

Abstract

In this research, the different characteristics of MoSe2 and N‐doped MoSe2 monolayers were studied using density functional theory calculations. The negative cohesive energy (−5.216 eV for MoSe2 and −5.333 eV for N‐MoSe2) verified their energetical stability. The variation of structural, electronic, and optical properties of MoSe2 and N‐MoSe2 via adsorption of PH3, C2N2, and HN3 gases are studied. The N‐doping results in a stronger adsorbent‐gas interaction, resulting in maximum adsorption energy of −0.036, −0.033, and −0.198 eV for the selected gases. The MoSe2 and N‐MoSe2 monolayers showed a direct band gap of 1.48 eV and 1.09 eV, respectively. However, upon interaction with the gases, a notable shift in the band gap of both adsorbents is observed. N‐MoSe2 showed semiconductor‐to‐conductor transition via C2N2 and HN3 adsorption. The sensitivity of MoSe2 for the selected gases has improved remarkably via N‐doping. Also, HN3 gas can be easily detected by the N‐MoSe2 monolayer due to the greater changes in work function (0.45 eV). The absorption coefficient of both adsorbents is over 105 cm−1 order in the UV region, which suffers a mild peak shifting due to gas adsorption. This study suggests that N‐MoSe2 can be a potential candidate for selected gas sensing.