Surface Chemistry of C2H4, CO, and H2 on Clean and Graphite Carbon-Modified Co(0001) Surfaces

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• 作者：Lingshun Xu ; Yunsheng Ma ; Yulin Zhang ; Bohao Chen ; Zongfang Wu ; Zhiquan Jiang ; Weixin Huang
• 刊名：Journal of Physical Chemistry C
• 出版年：2011
• 出版时间：March 3, 2011
• 年：2011
• 卷：115
• 期：8
• 页码：3416-3424
• 全文大小：1152K
• 年卷期：v.115,no.8(March 3, 2011)
• ISSN：1932-7455

文摘

Chemisorption and surface reactions of C₂H₄, CO, and H₂ on clean and graphite carbon-modified Co(0001) surfaces have been investigated by thermal desorption spectroscopy, X-ray photoelectron spectroscopy, and low-energy electron diffraction. The chemisorption and decomposition behaviors of C₂H₄ depend largely on the vacant sites available on clean Co(0001) at 130 K. C₂H₄ chemisorbs dissociatively to produce C₂H₂(a) and H(a) at low exposures but both dissociatively and molecularly to produce C₂H₄(a), C₂H₂(a), and H(a) at large exposures. Upon heating, some C₂H₄(a) desorbs and vacates surface sites, which results in the simultaneous decomposition of C₂H₄(a) into C₂H₃(a) and H(a). At 350 K, C₂H₃(a) either undergoes further dehydrogenation into C₂H₂(a) and H(a) or hydrogenates to produce C₂H₄. C₂H₂(a) then completely dehydrogenates to graphite carbon and H₂ at 424 K. Graphite carbon modified Co(0001) surfaces were prepared by the thermal decomposition of C₂H₄ on clean Co(0001). The graphite carbon exerts both site-blocking effect and electronic effect on the reactivity of Co(0001) surface, suppressing the decomposition of C₂H₄(a) and weakening the interaction between the Co surface and CO(a) and H₂(a). These results provide fundamental understandings of elementary steps of relevant heterogeneous catalytic reactions catalyzed by Co-based catalysts.