Interaction of NO with RuO₂(110) Surface:  A First Principles Study

Abstract

We report results of density functional theory calculations of the interaction of NO with the stoichiometric RuO 2 (110) surface that provide insights into the experimentally observed lack of reactivity for the system. We find that NO adsorbs on top of the undercoordinated Ru (Ru-cus) with an upright axis, and the adsorption energy (with zero-point contribution) changes from 1.61 eV for 0.5 ML to 1.49 eV for 1 ML coverage. Once all Ru-cus sites are occupied, NO adsorbs on O-bridge sites with adsorption energy of 0.66 eV, forming an asymmetric O‚‚‚N-O surface complex. We also find a high dissociation barrier of 3.22 eV for NO on Rucus. Although the activation energy for oxidation of NO is calculated to be about 1.2 eV, the location of the final state makes the formation of NO 2 only transient with a large probability of reverting back to NO. Additionally, the total energy difference for the reaction NO + NO f N 2 O + O on RuO 2 (110) is found to be about 1.35 eV. Comparison of results with those for a similar overlayer of CO on the surface show the NO-Ru-cus bond to be stronger than CO-Ru-cus, the difference arising from the contribution of the unpaired 2π* electrons for the former.

Density Functional Theory Study of the Oxidation of Ammonia on RuO2(110) Surface

“…These values are consistent with those obtained from recent DFT calculations. 30 Relative to the NO molecule in the gas phase, the value of d(N-O) of NO cus is slightly shortened by 0.02 Å. Another N-atom-containing product, N 2-cus , is relatively weakly bonded to the surface; its interaction energy is -0.53 eV and the Ru-N bond length (2.02 Å) is significantly longer than that of adsorbed NO cus .…”

Molecular adsorption of NO on PdO(101)

“…Prior investigations of NO adsorption on the RuO2(110) surface may aid in developing general insights for understanding how NO interacts with surfaces of late transition-metal oxides. This work shows that NO can adsorb in multiple configurations and binding sites on RuO2(110) [12][13][14]. Both experiments and computations indicate that NO preferentially binds in an atop-configuration on the coordinatively unsaturated (cus) Ru sites of RuO2(110).…”

NO Oxidation on Platinum Group Metals Oxides: First Principles Calculations Combined with Microkinetic Analysis

“…In addition, the reaction of NO + O → NO 2 is less exothermic relative to CO + O → CO 2 and is prone to equilibrium-limiting over temperatures of practical interest. The conclusion obtained from CO oxidation is not necessarily applicable to NO oxidation . For example, RuO 2 is inert for NO oxidation despite its high activity for CO oxidation.…”

“…The conclusion obtained from CO oxidation is not necessarily applicable to NO oxidation. 22 For example, RuO 2 is inert for NO oxidation despite its high activity for CO oxidation. Thus, a systematic investigation on the activities of metal oxides and their intrinsic properties for NO oxidation is desirable.…”