Dinitrosyl formation as an intermediate stage of the reduction of NO in the presence of MoO3

Abstract

We present first-principles calculations in the framework of density-functional theory and the pseudopotential approach, aiming to model the intermediate stages of the reduction of NO in the presence of MoO3(010). In particular, we study the formation of dinitrosyl, which proves to be an important intermediate stage in the catalytic reduction. We find that the replacement of an oxygen of MoO3 by NO is energetically favorable, and that the system lowers further its energy by the formation of (NO)2. Moreover, the geometry and charge distribution for the adsorbed dinitrosyl indicates a metal-oxide mediated coupling between the two nitrogen and the two oxygen atoms. We discuss the mechanisms for the dinitrosyl formation and the role of the oxide in the reaction.[To be published in the Journal of Chemical Physics]

Is Single Layer MoS2 Stable in the Air?

“…This bond is also very strong, having a calculated bond order of 1.93 . The short Mo−O bonds to non‐bridging oxygens are 1.70 Å, which is again very close to the corresponding value for bulk MoO 3 (1.67 Å) . Remarkably, the binding energy of a single MoO 3 unit at the edge is 2.39 eV, so a very large energy input is required to detach MoO 3 groups from the edge, in contrast to the removal of a SO 2 group.…”

“…Figure shows that at the oxidised edge, one of the oxygen atoms interconnects neighbouring Mo atoms, while the other oxygen centres are all bonded to single Mo. The length of the interconnecting Mo−O bonds is 1.91 Å, in good agreement with the corresponding Mo−O bond in bulk MoO 3 (1.94 Å) . This bond is also very strong, having a calculated bond order of 1.93 .…”

“…The length of the interconnecting MoÀOb onds is 1.91 ,i ng ood agreement with the corresponding MoÀOb ond in bulk MoO 3 (1.94 ). [34] This bond is also very strong, having ac alculated bond order of 1.93. [35] The short MoÀOb onds to non-bridging oxygens are 1.70 ,w hich is again very close to the corresponding value for bulk MoO 3 (1.67 ).…”

“…[35] The short MoÀOb onds to non-bridging oxygens are 1.70 ,w hich is again very close to the corresponding value for bulk MoO 3 (1.67 ). [34] Remarkably,t he binding energy of as ingle MoO 3 unit at the edge is 2.39 eV,s o av ery large energy input is required to detach MoO 3 groups from the edge, in contrast to the removal of aS O 2 group. The binding energy stems from the strong bonds interconnecting oxygen and molybdenum atoms.…”

Locally Refined Multigrid Solution of the All-Electron Kohn–Sham Equation

“…In this work we employ the generalized Broyden method 43 which has been successfully implemented in the past in electronic structure calculations. 44,45 We used this method in order to yield a new approximation of all the occupied wavevectors (for which f k ̸ = 0), V xc , and V H , by mixing each vector with its values from several previous relaxation sweeps. The weights of mixing are chosen such that they minimize the overall residual of the Eqs.…”