  Atmospheric pressure plasma (APP) generates highly reactive species that are
useful for surface activations. We demonstrate a fast regeneration of iron
oxides, that are popular catalysts in various industrial processes, using
microwave-driven argon APP under ambient condition. The surface treatment of
hematite powder by the APP with a small portion of hydrogen (0.5%) lowers the
oxide's reduction temperature. A near-infrared laser is used for localized
heating to control the surface temperature. Controlled experiments without
plasma confirm the catalytic effect of the plasma. Raman, XRD, SEM, and XPS
analyses show that the plasma treatment changed the chemical state of the
hematite to that of magnetite without sintering.
