Exploring Mechanism of H2 Adsorption on Surfaces of Iron Oxides by Density Functional Theory Calculation

Abstract

With the advance of low-carbon transformation of ironmaking and steelmaking, it is crucial to understand the adsorption and reduction mechanisms of hydrogen during the reduction of Fe₂O₃ to Fe for the improvement and widespread adoption of hydrogen-based direct reduction technologies. Density functional theory (DFT) calculations, known for their exceptional ability to calculate adsorption sites, adsorption energies, and electron transfer processes, have become an essential tool for investigating the mechanisms of gas adsorption on iron oxide surfaces. This paper reviews the research progress on the adsorption behavior of gas molecules during the hydrogen reduction of iron oxides, namely Fe₂O₃, Fe₃O₄, and FeO, using DFT computational methods, focusing on the adsorption mechanisms of H₂ on various oxide surfaces. H₂ adsorption usually involves interactions with surface oxygen atoms, leading to dissociative adsorption and a spontaneous exothermic process. Owing to different surface structures of the oxides and variations in computational methods, there are significant differences in the adsorption behavior and mechanisms of H₂ on these surfaces. Therefore, this work also discusses the influence of methodological parameters of DFT calculations, expecting to fully understand H₂ adsorption behaviors in the Fe₂O₃ reduction process.