Speaker
Description
Despite iron being a benign, abundant, and active material for carbon dioxide (CO2) reduction into
fuels, the role of layer deposition thickness on its efficiency is not known. Density functional
theory (DFT) calculations were carried out to investigate how the thickness of Fe slabs influence
CO₂ activation. Specifically, we examined the adsorption of CO₂ on Fe surfaces ranging from a
monolayer to six layers, analyzing adsorption energies, geometries, charge transfer behavior, and
electronic properties through density of states (DOS) analysis and charge density calculations. A
trend in charge transfer values across iron layers from monolayer to six layers, with values of
1.01 eV, 1.04 eV, 1.09 eV, 1.08 eV, 1.08 eV, and 1.09 eV, respectively. This trend closely mirrored
the pattern seen in CO₂ bond length elongation. The results indicate that CO₂ activation increases
progressively from a single layer up to three layers, beyond which further increases in layer
thickness yield little to no additional enhancement, suggesting a plateau in activation efficiency.
The projected density of states (PDOS) and charge density difference (CDD) analyses clearly
showed changes in the electronic structure of the CO₂ molecule after adsorption. They revealed
electron transfer from the iron slabs to the CO₂, indicating activation. These findings offer useful
guidance for experimentalists developing iron-based catalysts. For CO₂ activation, despite a layer
having the least activity, slabs with up to three atomic layers are effective, as adding more layers
does not significantly enhance activation. Thus, efforts can focus on optimizing thinner slabs,
which are both efficient and practical for catalytic use.
Keywords: Density functional theory, CO2 reduction, Surface reaction, Surface adsorption, CO2
activation