A DFT study on the N2O reduction by CO molecule over silicon carbide nanotubes and nanosheets

Abstract

In this work, we study the nitrous oxide (N₂O) reduction by CO over zigzag (6,0) silicon carbide nanotubes (SiCNT) and nanosheets (SiCNS) by means of density functional theory calculations. Different N₂O and CO adsorption configurations are examined over these surfaces. The results indicate that the adsorption of N₂O via a [3 + 2]-cycloaddition is the most favorable structure over the SiCNT and SiCNS. For both surfaces, the N₂O reduction proceeds via two different steps: (1) N₂O → N₂ + O*, and (2) O* + CO → CO₂. In addition, the length and curvature effects of the SiCNT on the adsorption of gas molecules are studied in detail. The activation energy (E_act) of the N₂O → N₂ + O* step over (6,0) SiCNT (0.71 eV) is considerably smaller than that of SiCNS (1.12 eV). Also, with the reduction of the tube diameter, the N₂O decomposition reaction proceeds with a smaller E_act.