Phase transformation-induced crystal plane effect of iron oxide micropine dendrites on gaseous toluene photocatalytic oxidation

Hematite (α-Fe2O3), magnetite (Fe3O4), and maghemite (γ-Fe2O3) micropine dendrites were synthesized by a facile hydrothermal method and oxidation-reduction process. The samples have been thoroughly characterized by various physicochemical techniques. The adsorption ability, quantum efficiency, and the photo-induced charge separation of the electron–hole pair in the samples were demonstrated by the XPS, FTIR, UV–vis, and PL spectroscopy. The α-Fe2O3 showed higher catalytic activity than the other two samples for photocatalytic oxidation of gaseous toluene. This may be attributed to the phase transformation-induced crystal plane effect of the α-Fe2O3 micropine dendrite, which has relatively more reactive crystal planes {0 0 1} and {1 1 0} exposed on the surface of α-Fe2O3.