Density Functional Theory Study of the Oxidation of Ammonia on the IrO2(110) Surface

作者：Wang Chia Ching; Siao Shih Syong; Jiang Jyh Chiang^*

来源：Langmuir, 2011, 27(23): 14253-14259.

DOI：10.1021/la203339z

In this study, we employed density functional theory (DFT) to investigate the oxidation of ammonia (NH3) on the IrO2(110) surface. We characterized the possible reaction pathways for the dehydrogenation of NHx species (x = 1-3) and for the formation of the oxidation products N-2, N2O, NO, NO2, and H2O. The presence of oxygen atoms on coordinatively unsaturated sites (O-cus) of the oxygen-rich IrO2(110) surface promotes the oxidation of NH3 on the surface. In contrast, NH3 molecules prefer undergoing desorption over oxidation on the stoichiometric IrO2( 110) surface. Moreover, the O-cus atoms are also the major oxidants leading to the formation of oxidation products; none of the oxidations mediated by the bridge oxygen atoms were favorable reactions. The energy barrier for formation of H2O as a gaseous oxidation product on the IrO2(110) surface is high (from 1.83 to 2.29 eV), potentially leading to the formation of nitrogen-atom-containing products at high temperature. In addition, the selectivity toward the nitrogen-atom-containing products is dominated by the coverage of O-cus atoms on the surface; for example, a higher coverage of O-cus atoms results in greater production of nitrogen oxides (NO, NO2).

• 出版日期2011-12-6