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Theoretical insights into the effect of terrace width and step edge coverage on CO adsorption and dissociation over stepped Ni surfaces

Abstract

Vicinal surfaces of Ni are model catalysts of general interest and great importance in computational catalysis. Here we report a comprehensive study conducted with density functional theory on Ni[n(111)×(100)] (n=2, 3 and 4) surfaces to explore the effect of terrace width and step edge coverage on CO adsorption and dissociation, a probe reaction relevant to many industrial processes. The coordination numbers (CN), the generalized coordination numbers ( ) and the d band partial density of states (d-PDOS) of Ni are identified as descriptors to faithfully reflect the difference of the step edge region for Ni[n(111)×(100)]. Based on analysis of the energy diagrams for CO activation and dissociation as well as the structural features of the Ni(311), Ni(211) and Ni(533) surfaces, Ni(211)(n=3) is proposed as a model of adequate representativeness for Ni[n(111)×(100)] (n≥3) surface groups in investigating small molecule activation over such stepped structures. Further, a series of the Ni(211) surfaces with the step edge coverage ranging from 1/4 to 1 monolayer(ML) were utilized to assess their effect on CO activation. The results show that CO adsorption is not sensitive to the step edge coverage, which could readily approach 1 ML under CO-rich atmosphere. In contrast, CO dissociation manifests strong coverage dependence when the coverage exceeds 1/2 ML, indicating significant adsorbate-adsorbate interactions emerge. These results are conducive to theoretical studies of metal-catalyzed surface processes where the defects play a vital role.

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Publication details

The article was received on 09 May 2017, accepted on 14 Jun 2017 and first published on 14 Jun 2017


Article type: Paper
DOI: 10.1039/C7CP03050A
Citation: Phys. Chem. Chem. Phys., 2017, Accepted Manuscript
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    Theoretical insights into the effect of terrace width and step edge coverage on CO adsorption and dissociation over stepped Ni surfaces

    K. Yang, M. Zhang and Y. Yu, Phys. Chem. Chem. Phys., 2017, Accepted Manuscript , DOI: 10.1039/C7CP03050A

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