Adsorption of NO, NO2 on Rh Embedded h-BN Monolayer: A First-Principles Study

Abstract Density functional theory calculations have been made to investigated the adsorption and sensing properties of harmful nitrogen oxides (NO, NO2) on rhodium (Rh) doped hexagonal boron nitride (BN) to explore the feasibility of Rh-doped BN (Rh-BN) based gas sensor. For each gas molecule, various adsorption positions and orientations were examined. The favorable adsorption configuration has been established and the corresponding adsorption energy has been calculated. Besides, to understand the adsorption mechanism, The properties such as electron density, the energy band structure, state density of states, and charge transfer of the adsorption system were investigated in greater detail. The calculations indicate that the most stable structure is that the Rh atom located directly above the N atom, and a stable chemical bond with a length of 2.096 Å formed between the Rh atom and N atom, with a significant binding energy (𝐸𝑏) of -1.561 eV. Then, adsorption performance of Rh-BN monolayer upon nitrogen oxides is in order as NO2 > NO, with the adsorption energy (𝐸𝑎) 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, many levels of impurities are introduced into the intrinsic BN band structure, thereby improving the interaction between BN and adsorbed gas molecules. Following adsorption of NO and NO2, the band gap (Eg) of the doping system is wider. It has been demonstrated that gas adsorption reduces the electrical conductivity of the system, but increases the sensitivity of the system. The above calculation and analysis are of great importance for the exploration of the Rh-BN single layer as innovative gas detection material.