Mechanistic insights into hydrogen-rich ironmaking via high-temperature reconstruction of FeO (111): p-band center modulation governing CO/H₂ competitive reduction

Hydrogen-rich ironmaking technology, recognized as an environmentally sustainable and economically viable innovation, has garnered significant attention in recent years. This study addresses critical challenges associated with the reduction of iron oxides in hydrogen-rich ironmaking processes. Employing a multi-scale methodology that integrates thermogravimetric analysis, in-situ X-ray diffraction (XRD), Ab Initio Molecular Dynamics (AIMD) simulations, and Density Functional Theory (DFT) calculations, we elucidate the high-temperature reconstruction dynamics of the FeO (111) surface and its regulatory influence on the competitive reduction mechanisms of CO and H2. At elevated temperatures, the FeO (111) surface undergoes a progressive dynamic reconstruction from the surface inward, resulting in increased atomic spacing and a corresponding attenuation of characteristic XRD peak intensities. This structural transformation is accompanied by significant alterations in the surface electronic configuration and the electrophilic properties of active sites. In the context of the synergistic reduction and competitive interactions between CO and H2, CO demonstrates a preferential adsorption at the atop sites of Fe atoms, whereas following H2 dissociation, the most stable configuration involves two hydrogen atoms occupying atop positions on oxygen atoms. Correlation analysis between adsorption energies and electronic band centers reveals a pronounced negative correlation (-0.9989) between the CO adsorption energy and the p-band center, underscoring the critical role of p-orbital hybridization in CO adsorption. Furthermore, the dissociative adsorption of H2 molecules inhibits subsequent CO adsorption on the surface. Additionally, in the reduction process, the energy barrier for the non-dissociative adsorption pathway of H₂ is found to be lower than that of the dissociative adsorption pathway. Consequently, this research proposes that modulating the p-band center energy level of iron oxides can effectively regulate the competitive reduction dynamics between CO and H2, thereby enhancing macroscopic reduction efficiency.