Dresden 2017 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 107: Heterogeneous Catalysis: Theory II
O 107.2: Vortrag
Freitag, 24. März 2017, 10:45–11:00, TRE Phy
CH2 Stabilization at Steps on Ru(0001) by Co-Adsorbates — Xunhua Zhao1, Harald Kirsch1, Zefeng Ren2, •Sergey V. Levchenko1, and R. Kramer Campen1 — 1Fritz-Haber-Institut der MPG, Berlin, DE — 2Peking University, Beijing, CN
Despite numerous studies, the stability of various one-carbon (1C) species, which determines the hydrocarbon-chain growth mechanism in industrially important processes such as the Fischer-Tropsch (FT) synthesis, is still debated. In particular, it was shown recently that H co-adsorption at Ru(0001) terraces stabilizes adsorbed CH2, which makes it a much more likely candidate for the chain building block [1]. In this work, we use DFT with the PBE functional plus a van der Waals interaction correction vdWsurf [2] to study the effect of CH co-adsorption on the stability of CH2 at stepped Ru(0001) surface. We show that both the barrier for CH2 dissociation and that for the diffusion of CH away from the steps increase 2- to 3-fold compared to isolated 1C species. The theoretical study explains the vibrational sum-frequency generation spectroscopy measurements of this system [3]. The results of the combined theoretical/experimental study highlight the large influence of co-adsorbates on step-bound 1C moieties and provide means of reconciling previous apparently contradictory results on the FT synthesis.—[1] H. Kirsch et al., J. Catal. 320, 89 (2014); [2] V. Ruiz et al., PRL 108, 146103 (2012); [3] H. Kirsch et al., JPC C 120, 24724 (2016).—X. Zhao’s current address: Chemistry Department, Princeton University, Princeton, NJ 08544, USA.—This work received funding from the UNICAT Cluster of Excellence.