Adsorption of NO and NO2 on Rh-Doped Hexagonal Boron Nitride Monolayers: A First-Principles Study

Density functional theory (DFT) calculations have been made to investigate the adsorption and sensing properties of harmful nitrogen oxides (NO, NO2) on rhodium (Rh) doped hexagonal boron nitride (BN) to explore the feasibility of constructing Rh-doped BN (Rh-BN) based gas sensors. For each gas molecule, various adsorption positions and orientations were examined. The calculations illustrate that the most stable structure is that the Rh atom is located directly above the N atom, and a stable chemical bond with a length of 2.096 angstrom formed between the Rh atom and N atom, with significant binding energy (E-b) of -1.561 eV. Moreover, the adsorption performance of the Rh-BN monolayer towards nitrogen oxide is in the order as NO2>NO, with E-a of -3.919 eV and -3.318 eV, respectively. This indicates that the Rh-BN single layer possesses ideal adsorption and sensing properties. Furthermore, by doping the Rh atom, impurities are introduced into the intrinsic BN band structure, which improves the interaction between BN and adsorbed gas molecules. Following the adsorption of NO and NO2, the bandgap (E-g) of the doped BN is wider, which indicates that gas adsorption reduces the conductivity of the system, but enhances the sensitivity of the system. The above calculation and analysis are of great importance for the exploration of the Rh-BN monolayer as an innovative gas detection material.