Teoria do funcional da densidade aplicada ao estudo da interação entre nanogaiolas B12 N12 puras e dopadas com cobre e níquel com os gases tóxicos CO e CNCl

Abstract

This thesis presents a comprehensive study of the adsorption of carbon monoxide (CO) and cyanogen chloride (CNCl) on B12N12 pristine and copper and nickel-doped surfaces using calculations based on density functional theory. Firstly, from our systematic review of the literature, we infer that a pure B12N12 nanocage can selectively detect O3, HNO, NO, CO, CNCl, and CNF gases. In contrast, metal-modified B12N12 nanocage can detect a wider range of gases such as CO, NH3, PH3, AsH3, SO2, O3, COCl2, NCCN, and CNCl. However, few studies have discussed the interference effects due to the presence of other gases in the atmosphere and/or the incorporation of different structural modifications into the nanocage. Secondly, we observed that: i) the increase in the electric field (

⃗EF⃗⃗⃗⃗ ) in the negative direction favored the adsorption of CO gas, while the increase in ⃗EF⃗⃗⃗⃗ in the positive direction favored the desorption of the CO molecule on the B12N12; ii) increase in the ⃗E⃗⃗⃗F⃗ resulted in an increase in the sensitivity, for the B3LYP and B97D functionals, from –0.514 to +0.514 V/Å; iii) the functional with dispersion correction (B97D) described best system B12N12–CO, as a function of the application of the electric field. Demonstrated the capability of B12N12 as a sensor for potential applications in the detection of CO under an ⃗EF⃗⃗⃗⃗ . Thirdly, it was found that the gas adsorption performance of B12N12 is improved due to the introduction of the Cu atom, but the interaction between CO and B12N11Cu, Cu@B12N12, Cu@b64, and Cu@b66 nanocages is strong, limiting applications for gas detection. Particularly, the CuB11N12 system shows moderate an adsorption energy (Eads = – 0.6 eV) and a high electronic sensitivity (ΔEgap = 81.6%) toward CO gas, compared to other modified systems. Furthermore, it was found that CuB11N12 presented low recovery time (14 ms) and high selectivity for CO detection, setting up as a superior material for applications involving the selective detection of CO gas. Finally, we observed that the CNCl molecule was observed to chemically adsorb on all MB11N12 (M = Fe–Zn) nanocages, but a stronger interaction occurred on the FeB11N12 and CoB11N12 nanocages, a moderate interaction occurred on the B12N12, NiB11N12, CuB11N12, and ZnB11N12 surfaces (σ-donation being more effective than π-back-bonding). However, the NiB11N12 and CuB11N12 nanocages showed the highest ΔEgap values (79.31% and 87.50%, respectively) for the adsorption of CNCl gas. Furthermore, based on performance analysis and comparison with previous results reported in the literature, it was found that NiB11N12 and CuB11N12 nanocages were superior materials for application in the detection of the CNCl toxic gas.