Identification of Active Sites over Fe₂O₃-Based Architecture: The Promotion Effect of H₂SO₄ Erosion Synthetic Protocol

Knowledge of tuning the composition and structure of the active sites is crucial for understanding and improving the properties of catalysts. Here, we report that selective catalytic reduction (SCR) of NOx using ammonia over Fe2O3 nanoparticle is boosted by a nanometric Fe2(SO4)3 shell, which is generated via a facile H2SO4 erosion synthetic protocol. The Fe2O3–H2SO4 erosion sample consists of a well-defined hexagon shape Fe2O3 core and a 1 nm thin Fe2(SO4)3 shell formed by H2SO4 erosion as evidenced by transmission electron microscopy measurements. A set of control experiments show that pure Fe2O3 or Fe2(SO4)3 alone cannot fully account for the high catalytic performance of the Fe2O3–H2SO4 erosion sample. By combining electron microscopy, activity measurement, surface area titration, and temperature-programmed desorption and surface reaction, we show that reactants are activated within a zone at the surface interface of Fe2O3 and Fe2(SO4)3 on the as-prepared Fe2O3–H2SO4 erosion sample.