DFT study of the chlorine promotion effect on the ethylene adsorption over iron clusters

• Electronic structures and properties of Fen in the presence of Cl have been studied.
• Hoping to construct the small doped clusters as a local model for metal catalyst.
• Understanding how electronic perturbations induced by Cl can enhance the reactivity of Fe.
• Promotional impact of Cl on the ethylene adsorption over low-chlorinated clusters.
• Number of Cls is a key factor in the modification of ethylene chemisorption on iron.

This work explores how electronic perturbations induced by chlorine atoms can enhance the activity of iron toward ethylene. The metal clusters include Fen (n = 2–4), in which each adatom (Cl) has an inclination to be adsorbed at the bridge site with electrostatic interaction. Ethylene adsorption over pure and chlorine-doped FenClm (n,m ≤ 4) clusters is analyzed using density functional theory (DFT) calculations, in π and di-σ adsorption modes. One of the interesting features is that the adsorption mode of ethylene changes by going from trimers to tetramers. Ethylene never orients toward di-σ mode for FeFe bond in Fe2 and Fe3 series, while this orientation is preferred in tetramers. Our results demonstrate that the progressive change in the ethylene adsorption could not be sustained with increasing portion of chlorine in metal cluster. In this study, we attempt to provide a sensible justification for this phenomenon by the natural bond orbital (NBO) and quantum theory of atoms-in-molecules (QTAIM) analyses.

Promotional interplay between chlorine composition and ethylene adsorption over new Cl-doped iron clusters is studied to understand how electronic perturbations induced by Cl atoms can enhance the reactivity of iron. The Cl-addition into iron clusters results in a substantial improvement in ethylene adsorption and causes a noticeable increase in interaction energies in low-chlorinated clusters compared to the pure ones, which can be a reflection of some charge transfers.Figure optionsDownload high-quality image (109 K)Download as PowerPoint slide