DFT study of TM (Sc - Zn) modified B 12 N 12 nanocage as sensor for N2O gas selective detection

Nitrous oxide (N2O) is a toxic gas which has worrying environmental effects. In addition to its role as a greenhouse gas, N2O can also contribute to the destruction of the ozone layer. In order to mitigate the environmental effects of N2O, some actions are necessary to reduce its emissions. They include more efficient agricultural practices, responsible use of nitrogen fertilizers and more advanced technologies for the detection and capture of N2O. In order to contribute to the efficient detection of N2O in the atmosphere, the use of B12N12 nanocages in the development of chemical and optical sensors has been investigated. In this context, DFT-D3 and TD-DFT level calculations using the B3LYP functional and the 6-31 G(d,p) basis set were performed in this work to investigate the geometric, electronic and energetic parameters of N2O gas adsorption in pure B12N12 nanocages as well as those modified with TM (Sc - Zn) in five different configurations (TMB11N12, B12N11TM, TM@b(64), TM@b(66) and TM@B12N12). The results showed that N2O gas physically adsorbs in the B12N12 cage (E-ads = -0.14 eV) and in practically all the systems with encapsulated metal (TM@B12N12), except for Cu@B12N12, in which N2O interacts moderately (E-ads = -0.93 eV) and presented a satisfactory recovery time at room temperature (tau = 52 s). The electronic sensitivity of the systems to N2O adsorption was analyzed and Cu@B12N12 showed greater sensitivity (triangle E-gap = 72.3 %) compared to the other nanocages. Furthermore, the cage is capable of selectively differentiate the N2O molecule from the interfering gases studied (CO2, H2S, H2O, N-2, CH4 and H-2). The potential for a work function sensor was also investigated for all systems and Cu@B12N12 also showed the best response, with a 50.4 % variation in the system's work function upon gas adsorption. In short, based on the variation of energy gap, the variation of work function, TD-DFT and molecular dynamics calculations, the conclusion is that the Cu@B12N12 nanocage is stable and can be used as an electronic sensor material for the selective detection of N2O molecules in the environment.