Figure 1.

Band diagrams and schematic images of the surface reactions of an α-Fe₂O₃ nanograin under different atmospheres, while kept at the optimal operating temperature (i.e., 300 °C): (a) under inert atmosphere (e.g., Ar); (b) exposed to air (c) in the presence of H₂S diluted in air. Reproduced from [15], with permission from Elsevier.