Catalytic activity of Rhn/MegO-nanotube for NO adsorption and dissociation: A van der waals density functional study

Abstract

We have studied the adsorption and dissociation of nitric oxide (NO) on a series of interfaces consisting of a rhodium cluster (Rhn, n = 1–5) and an MgO nanotube, using van der Waals density functional theory calculations and have found that the Rhn clusters can tightly adhere to an MgO (100) nanotube. The change in the configuration of the nanotube substrate induces differences in the energetically preferred structures for some Rhn clusters (n > 2). With an MgO-nanotube substrate, the low dimensional Rhn clusters tend to be stable, and provide additional active sites to the NO. Hence they have an excellent ability to trap and dissociate NO. We see strong hybridization between N/O 2p and Rh 4d. Moreover, NO dissociation is activated, with the transition state below the reference state, indicating the possibility of the NO dissociating. Binding to NO also yields a change in the total magnetic moment of the Rhn/MgO-NT system, and this affects the adsorption energy of NO. Finally, we propose that the morphology of the metal clusters could be directly regulated by the configuration of the nanotube substrate, which encourages us to explore and design various types of nanotubes for different catalytic purposes.