Catalytic Synthesis of Nitric Monoxide at the AlN(0001) Surface: Ab Initio Analysis

Abstract

Molecular nitrogen and molecular oxygen adsorption at the Alterminated AlN(0001) surface was investigated using ab initio simulations. It was shown that both species undergo barrierless dissociation during attachment to the surface. The H3 adsorption site was identified as the most favorable for both O and N adatoms. The adsorption energies for O 2 and N 2 were found to be 14.8 and 6.0 eV, respectively. At the clean surface, separate N and O adatoms have their energies 4.37 eV lower than the NO admolecule. At normal nitrogen pressures, the AlN(0001) surface is fully covered by nitrogen adatoms. It was shown for this coverage that adsorption of oxygen leads to creation of the NO admolecule which is a necessary step for nitric monoxide synthesis. The energetics of NO molecules is related to electronic charge transfer: from the two possible configurations, it is shown that T4 and H3 are donors and acceptors, respectively. The resulting coverage is the mixture of both configurations, controlled by electron charge balance. Thus, the ab initio modeling provides indication that AlN(0001) is the powerful catalyst for high pressure−high temperature synthesis of nitric monoxide (NO), indicating that AlN may be a candidate for applications in industrial mass synthesis of nitrogen-based materials such as fertilizers or explosives.

Study of odd–even effects in physisorption and chemisorption of Ar, N2, O2and NO on open shell Ag11–13+clusters by means of self-consistent van der Waals density functional calculations

“…26 As a first step to understand these processes, apart from the action of the support, density functional calculations have been done to explore NO x adsorption on pure and doped silver clusters, 7,18 as well as the Ag(111) surface 27 and AlN(0001) surface. 28 DFT calculations show that NO interacts weakly with Ag n clusters (n r 8) and is preferably adsorbed in atop sites. 7 Experiments of adsorption and activation of NO on silver clusters with sizes up to one nanometer show that the interactions are dominated by electron transfer from silver to NO.…”