Interior surface (confinement effect) and exterior (odd-even effect) of Fe-BNNTs (n, 0) for CO oxidation: A computational view

摘要

In this work, a series of Fe embedded boron and nitrogen nanotubes, (Fe-BNNTs (n, 0)(B-vacancy), n = 8-13) are chosen to explore the catalytic activity for CO oxidation reaction. For the interior surface, CO oxidation reaction can only proceed on the Fe-BNNTs (n, 0) (n = 9-12) via Langmuir-Hinshelwood (LH) mechanism. Among four Fe-BNNTs with different tube diameters, the Fe-BNNT (12, 0)(in) exhibits superior catalytic activity, owe to its excellent confinement effect and being an ideal reaction vessel. For the exterior surface, the interesting odd-even effect of n is found: because of moderate O-2 adsorption energies E-ad (O-2) and negative Gibbs free energies (G), only Fe-BNNTs (n, 0) (n = 9, 11 and 13 (odd)) can catalyze CO oxidation reaction via LH and Eley-Rideal (ER) mechanisms, in which (11, 0)(out) exhibits excellent catalytic activity. Besides, the catalytic activity of interior surface is superior to that of exterior surface. We hope this work can provide a new option to enhance the catalytic activity of non-noble catalysts based on nanotubes.