The remarkable performance of a single iridium atom supported on hematite for methane activation: a density functional theory study

Methane is the major component of natural gas, and it significantly contributes to global warming. In this study, we investigated methane activation on the α-Fe(2)O(3)(110) surface and M/α-Fe(2)O(3)(110) surfaces (M = Ag, Ir, Cu, or Co) using the density-functional theory (DFT) + U method. Our study shows that the Ir/α-Fe(2)O(3)(110) surface is a more effective catalyst for C–H bond activation than other catalyst surfaces. We have applied electron density difference (EDD), density of states (DOS), and Bader charge calculations to confirm the cooperative CH⋯O and agostic interactions between CH(4) and the Ir/α-Fe(2)O(3)(110) surface. To further modify the reactivity of the Ir/α-Fe(2)O(3)(110) surface towards methane activation, we conducted a study of the effect of oxygen vacancy (O(V)) on C–H activation and CH(4) dehydrogenation. In the comparison of pristine α-Fe(2)O(3)(110), Ir/α-Fe(2)O(3)(110), and Ir/α-Fe(2)O(3)(110)–O(V) surfaces, the Ir/α-Fe(2)O(3)(110)–O(V) surface is the best in terms of CH(4) adsorption energy and C–H bond elongation, whereas the Ir/α-Fe(2)O(3)(110) surface catalyst has the lowest C–H bond activation barrier for the CH(4) molecule. The calculations indicate that the Ir/α-Fe(2)O(3)(110)–O(V) surface could be a candidate catalyst for CH(4) dehydrogenation reactions.