Adsorption of CO2 on the Surface of Fe(111): A First-Principles Study

Abstract

First-principle is used to study the structure parameters, adsorption energy, Bader charge, electronic density of states, charge-density transformation, and surface work function of CO2 molecule at various adsorption sites on the Fe(111) surface based on Density Function Theory (DFT). Results show that the CO2 molecule is absorbed on the Fe(111) surface by combining Fe–C and Fe–O multiple bonds. The type of adsorption of most configurations is chemisorption. The most stable structure is BS-Y, with an adsorption energy of −0.8115 eV. The order of stability of adsorption sites is bridge site > hcp site > fcc site > top site. Carbon dioxide mostly reacts with the uppermost two layers of Fe atoms and just partially with the lowermost two levels. In addition, the chemical bonds between CO2 molecule and Fe atoms are covalent, and the response mechanism is the hybridization of C-2s, C-2p, O-2s, and O-2p orbitals with Fe-3p, Fe-3d, Fe-4s orbitals, forming new chemical bonds. The BS-Y configuration has the smallest increment of work function, indicating that the lowest escape energy is required for the electron to escape from the surface.