DFT Study of NHx (x = 1−3) Adsorption on RuO2(110) Surfaces

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• 作者：Chia-Ching Wang ; Ya-Jen Yang ; Jyh-Chiang Jiang*
• 刊名：Journal of Physical Chemistry C
• 出版年：2009
• 出版时间：February 19, 2009
• 年：2009
• 卷：113
• 期：7
• 页码：2816-2821
• 全文大小：351K
• 年卷期：v.113,no.7(February 19, 2009)
• ISSN：1932-7455

文摘

We have used density functional theory (DFT) to investigate the adsorption of NH_x species (x = 1−3) onto RuO₂(110) surfaces at various monolayer coverages and onto oxygen-rich RuO₂(110) surfaces. We characterized the structures, vibrational frequencies, and detailed bonding interactions between the adsorbates and the surfaces. The binding energy increased as the number of hydrogen atoms bonded to the N atom decreased, i.e., NH_3-cus binds most weakly to the surface, whereas NH_cus has the highest binding energy. We investigated the nature of the metal−NH_x bonding through analyses of the density of states (DOS) and electron density difference contour maps. The DOS analysis allowed us to characterize the state interactions between the NH_x species and the surface; the electron density difference maps provided evidence that was consist with the DOS analysis. A greater number of state interactions led to the higher binding energy of an NH_x species: for NH_3-cus bound through a single σ bond, the binding energy was 1.56 eV; it increases to 4.23 eV when two π bonds were present in the NH_cus bonding mode. In addition, hydrogen bonding played an important role in the binding of NH_3-cus and NH_cus, especially for the weakly coordinated NH_3-cus. The formation of hydrogen bonds was evident from changes in the bond length and stretching frequency of the N−H bonds.