Modulation the reaction paths of oxygen removal by electronic effects for Fe5C2(100) surfaces

This study employed spin-polarized density functional theory and investigated the removal of surface oxygen on Fe5C2(100) surfaces substituted with first-row transition metals. It was observed that the substituted metals with lower electronegativity, such as Cr and Mn, could hinder the removal of surface oxygen. Conversely, substituted metals with higher electronegativity, such as Co, Ni, and Cu, facilitates the removal of surface oxygen. The results revealed a clear correlation between the energy barrier for oxygen removal and the electronegativity of substituted metals, which provides a straightforward and efficient approach to estimate the energy barrier for oxygen removal on iron carbide surfaces. Furthermore, the study demonstrated that the oxygen removal pathway is dependent on the electronegativity of substituted metals. For Cr and Mn substituted surfaces (low electronegativity), the oxygen removal via CO2 pathway is preferable both in thermodynamics and kinetics, while for Cu substituted surfaces (high electronegativity), the hydrogenation of O to H2O is more favorable. These findings reveal the significance of electronic promoters in catalyst design.