Center for Electrochemical Engineering Research, Department of Chemical and Biomolecular Engineering, Stocker Center 165, Ohio University, Athens, OH 45701, United States.
J Colloid Interface Sci. 2013 Jul 15;402:204-14. doi: 10.1016/j.jcis.2013.03.067. Epub 2013 Apr 11.
Density Functional Theory calculations with the hybrid B3LYP functional and the LANL2DZ and 6-311++g(**) basis sets were used to calculate the adsorption energies, geometries and vibration modes of N2Hz (z=0-4) molecules on a cluster of 20 platinum atoms. Based on calculated binding energies, the trans conformations of N2H4 and N2H2 were predicted to adsorb with one nitrogen in contact with the cluster; N2H3 and N2H radicals adsorb with both nitrogen atoms in contact with the catalyst; while N2 was not found to adsorb to any appreciable degree. Calculated frequencies showed N-N bond stretching frequency occurs at 913 cm(-1) and 953 cm(-1) for N2H4 and N2H3, respectively and is blueshifted to 1603 cm(-1) and 1631 cm(-1) for N2H and N2H2, respectively. This trend suggests that the formation of this bond could indicate the presence of these species during ammonia oxidation as a shift from 900 to 1600 cm(-1) is expected when the single bond becomes a double bond. Finally, this study combined with earlier studies predicts the following trend for the adsorption energies of species formed: N2<H2O<NH3<N2H2<N2H4<N2H<N2H3<OH<NH2<NH<N.
采用杂交 B3LYP 泛函和 LANL2DZ 和 6-311++g(**)基组的密度泛函理论计算，计算了 20 个铂原子簇上 N2Hz（z=0-4）分子的吸附能、几何形状和振动模式。基于计算的结合能，预测反式构型的 N2H4 和 N2H2 以一个氮原子与簇接触的方式吸附；N2H3 和 N2H 自由基以两个氮原子与催化剂接触的方式吸附；而 N2 没有被发现以任何可观的程度吸附。计算频率表明，N2H4 和 N2H3 的 N-N 键伸缩频率分别为 913 cm(-1)和 953 cm(-1)，而 N2H 和 N2H2 的 N-N 键伸缩频率分别蓝移至 1603 cm(-1)和 1631 cm(-1)。这一趋势表明，当单键变为双键时，从 900 到 1600 cm(-1)的位移可能表明这些物种在氨氧化过程中存在，因为形成该键。最后，这项研究与早期研究相结合，预测了形成的物种吸附能的以下趋势：N2<H2O<NH3<N2H2<N2H4<N2H<N2H3<OH<NH2<NH<N。
