Atomic and molecular adsorption on Fe(110)

• Published in: Surface science Vol. 667; pp. 54 - 65
• Main Authors: Xu, Lang, Kirvassilis, Demetrios, Bai, Yunhai, Mavrikakis, Manos
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.01.2018; Elsevier BV
• Subjects: Adsorbates; Adsorption; Ammonia; Binding sites; Carbon monoxide; Catalysis; Chemical reactions; Chemical synthesis; Decomposition reactions; Deformation; Density functional theory; Diffusion; Diffusion barriers; Fischer-Tropsch process; Iron; Mathematical analysis; Methane; Nitric oxide; Potential energy; Surface chemistry; Surface reactions; Density functional theory; Iron; Catalysis; Adsorption; Diffusion
• ISSN: 0039-6028; 1879-2758
• DOI: 10.1016/j.susc.2017.09.002

•Calculated binding structures and energies of adsorbates on Fe(110).•Calculated vibrational frequencies of adsorbates on Fe(110).•Estimated diffusion paths and barriers for adsorbates on Fe(110).•Evaluated thermochemistry for the complete decomposition of NH3, CH4, N2, CO, and NO on Fe(110). Iron is the principal catalyst for the ammonia synthesis process and the Fischer–Tropsch process, as well as many other heterogeneously catalyzed reactions. It is thus of fundamental importance to understand the interactions between the iron surface and various reaction intermediates. Here, we present a systematic study of atomic and molecular adsorption behavior over Fe(110) using periodic, self-consistent density functional theory (DFT-GGA) calculations. The preferred binding sites, binding energies, and the corresponding surface deformation energies of five atomic species (H, C, N, O, and S), six molecular species (NH3, CH4, N2, CO, HCN, and NO), and eleven molecular fragments (CH, CH2, CH3, NH, NH2, OH, CN, COH, HCO, NOH, and HNO) were determined on the Fe(110) surface at a coverage of 0.25 monolayer. The binding strengths calculated using the PW91 functional decreased in the following order: C > CH >N > O > S > NH > COH > CN > CH2 > NOH > OH > HNO > HCO > NH2 > H > NO > HCN > CH3 > CO > N2 > NH3. No stable binding structures were observed for CH4. The estimated diffusion barriers and pathways, as well as the adsorbate-surface and intramolecular vibrational modes of all the adsorbates at their preferred binding sites, were identified. Using the calculated adsorption energetics, we constructed the potential energy surfaces for a few surface reactions including the decomposition of methane, ammonia, dinitrogen, carbon monoxide, and nitric oxide. These potential energy surfaces provide valuable insight into the ability of Fe(110) to catalyze common elementary steps. [Display omitted]