MnFeO<i><sub>x</sub></i>@TiO<sub>2</sub> Nanocages for Selective Catalytic Reduction of NO with NH<sub>3</sub> at Low Temperature
Ziguo Cai, Guodong Zhang, Zhicheng Tang, Jiyi Zhang
Abstract
Based on Prussian blue analogues (PBAs), using the in situ self-assembly method, MnFeOx@TiO2 double-walled nanocages with a hollow and porous structure were constructed by annealing the core–shell structure of Mn3[Fe(CN)6]2·nH2O@Ti(OH)4. Compared with the MnFeOx single-walled nanocages without the TiO2 shell, the MnFeOx@TiO2 double-walled nanocages exhibited a better catalytic performance in selective catalytic reduction (SCR) with NH3 at low temperatures, and the NO removal efficiency could reach 80% at 145–260 °C. Establishing the TiO2 shell layer could effectively improve the adsorption and activation performance of the reactants. Through a series of characterizations, it was confirmed that the MnFeOx@TiO2 double-walled nanocages possessed a large specific surface area, abundant structural defects, and oxygen vacancies. Besides, the MnFeOx@TiO2 catalyst had more Mn4+ species, higher Fe3+ species, more surface-adsorbed oxygen (Oads) species, and a strong interaction between MnOx, FeOx, and the TiO2 shell, which led to better catalytic activity. At the same time, the MnFeOx@TiO2 double-walled nanocages exhibited satisfactory thermal stability and better H2O resistance.