VS2nanosheet as a promising candidate of recycle and reuse NO2gas sensor and capturer: a DFT study.

We describe the utilization of VS2nanosheet as high sensing response, reuse, and thermodynamic stability at room temperature NO2and NO gas sensors by using the density functional theory method. We focus on the electronic structures and adsorption energy toward a variety of gaseous molecules (such as O2, CO, H2O, NH3, NO, and NO2) adsorbed on the VS2nanosheet. The results show that chemical interactions existed between NO/NO2molecules and VS2nanosheet due to sizable adsorption energy and strong covalent (S-N) bonds. In particular, the adsorption energies, charge transfer and electronic properties between NO2adsorbed system is significantly changed compared with the other gas molecules (CO, NO, H2O, NH3, and O2) adsorbed systems under biaxial strains, which is effective to achieve the capture or reversible release of NO2for cycling capability. Our analysis indicates that VS2nanosheet is promising as electrical devices candidate for NO2high-performance gas sensor or capturer.

Formation Mechanism, Geometric Stability and Catalytic Activity of a Single Iron Atom Supported on N-Doped Graphene.

Based on density functional theory (DFT) calculations, the formation geometries, stability and catalytic properties of single-atom iron anchored on xN-doped graphene (xN-graphene-Fe, x=1, 2, 3) sheet are systemically investigated. It is found that the different kinds and numbers of gas reactants can effectively regulate the electronic structure and magnetic properties of the 3 N-graphene-Fe system. For NO and CO oxidation reactions, the coadsorption configurations of NO/O2 and CO/O2 molecules on a reactive substrate as the initial state are comparably analyzed. The NO oxidation reactions through the Langmuir-Hinshelwood (LH) and Eley-Rideal (ER) mechanisms have relatively smaller energy barriers than those of the CO oxidation processes. In comparison, the preadsorbed 2NO reacting with 2CO molecules (2NO+2CO→2CO2 +N2 ) through ER reactions (<0.4 eV) are energetically more favorable processes. These results can provide beneficial references for theoretical studies on NO and CO oxidation and designing graphene-based catalyst for toxic gas removal.