Abstract
Abstract This contribution investigates chlorine (Cl) interaction with the Fe(100) surface, with a focus on governing adsorption energies and geometrical features at the nanoscale using the density functional theory (DFT) approach. The Cl/Fe(100) system can be considered as a building block to create nanosystems with specific and desired electronic, material, mechanical, or environmental properties. We report adsorption energies, surface relaxations. and buckling distances for Cl adsorbed as a function of Cl coverage. The computational DFT framework employs a vdW-DF functional with coverages varying from 0.25 to 1 ML. Adsorption at a bridge site with coverage of 0.5 ML appears to be the most preferred site, with an adsorption energy of −4.44 eV. For all coverages, Cl adsorption at the bridge and hollow sites incurs slightly higher adsorption energies than adsorption at the top (T) site. The potential energy surface (PES) for the dissociation of a Cl molecule over the Fe(100) surface was calculated. Dissociative adsorption of the Cl molecule on Fe(100) ensues via a modest activation barrier of only 0.58 eV in a noticeably exothermic reaction of 2.94 eV. In agreement with experimental observations, the work function decreases upon Cl addition in reference to the clean iron surface. The electronic interaction between Cl and the Fe(100) surface was examined by calculating the differential charge density distribution of the most stable structure (B-0.5 ML). The vdW-DF interactions increase the adsorption energies and reduce the equilibrium distances when compared with the corresponding results from plain DFT.
Highlights
The profound chemical reactivity of iron surfaces with chlorine species is of prime importance for several environmental and industrial concerns, including chlorination of aromatic pollutants and corrosion of equipment [1,2,3]
Dowbin and Jones [1] investigated the adsorption of Cl2 on the Fe(100) surface using Auger electron spectroscopy (AES) and low energy electron diffraction (LEED) approaches at room temperature
Along the same line of enquiry, Hino and Lambert [2] studied the interaction of chlorine with the Fe(100) surface at low pressure using Auger spectroscopy, thermal desorption, X-ray and ultraviolet photoemission spectroscopy (XPS and UPS) techniques
Summary
The profound chemical reactivity of iron surfaces with chlorine species is of prime importance for several environmental and industrial concerns, including chlorination of aromatic pollutants (most notably notorious dioxins) and corrosion of equipment [1,2,3]. Dowbin and Jones [1] investigated the adsorption of Cl2 on the Fe(100) surface using Auger electron spectroscopy (AES) and low energy electron diffraction (LEED) approaches at room temperature They illustrated that the change in the work function is proportional to the chlorine coverage, with a maximum value of 1.43 eV at complete saturation. Along the same line of enquiry, Hino and Lambert [2] studied the interaction of chlorine with the Fe(100) surface at low pressure using Auger spectroscopy, thermal desorption, X-ray and ultraviolet photoemission spectroscopy (XPS and UPS) techniques. They demonstrated that the first adsorbate layer comprises FeCl2 rather than FeCl or nondissociated chlorine molecules. After the complete formation of a chemisorbed overlayer and at 300 K, the growth of the iron chloride layer is sustained
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