Simultaneously Enhancing Stability and Activity of Maghemite via Site‐Specific Ti(IV) Doping for NO Emission Control

Maghemite (γ‐Fe 2 O 3 ) is an environmentally benign catalyst for selective catalytic reduction (SCR) of NO with NH 3 , but its poor stability and low activity hamper its application in real NO emission control. Herein, we developed a stable Ti 4+ doped γ‐Fe 2 O 3 catalyst (Ti‐γ‐Fe 2 O 3 ) by site‐specific Ti 4+ doping at the octahedral sites rather than tetrahedral active sites (Fe 3+ Td ), as substantiated by synchrotron room‐temperature X‐ray diffraction (SXRD) data. In situ SXRD and thermogravimetric analysis (TG) data demonstrate that Ti 4+ cations occupying part of the octahedral sites lead to enhanced thermal stability of Ti‐γ‐Fe 2 O 3 with respect to γ‐Fe 2 O 3 , thus enabling Ti‐γ‐Fe 2 O 3 to stably operate at 400 °C under simulated normal SCR conditions. Fe L 3 ‐edge and O K ‐edge X‐ray absorption spectra show that the high‐valence Ti 4+ doping lengthens the Fe 3+ Td ‐O bonds, and activates the lattice oxygen species, thus improving the SCR activity. This work provides a feasible strategy for designing environmentally benign Fe 2 O 3 ‐based SCR catalysts with significant stability and high catalytic activity.