Single-Atom Ru-Implanted Metal–Organic Framework/MnO2 for the Highly Selective Oxidation of NOx by Plasma Activation

In an attempt to achieve the selective oxidation of NOx, a hybrid catalyst of single-atom-anchored metal organic frameworks (MOF, NH2-UiO-66) and MnO2 was constructed and used in the plasma catalytic process. Isolated Ru sites were successfully implanted into the structure of the MOF by simply stirring the mixed liquor containing both MOF and RuCl3, facilitating plasma discharge, NO/NO2 adsorption, and formation of •OH radicals. A special oxo-bridged Zr4+–O–Ru3+ was constructed to accelerate electron transfer and continuous proceeding of the reaction. Directional migration of generated electrons from MOF to Ru sites was witnessed when MOF was activated by plasma-induced "pseudo-photocatalysis". The total (100%) selective plasma-catalytic oxidation of NOx to NO2– and NO3– was achieved at an SIE of 75.3 J/L. The byproduct O3 was effectively degraded and utilized by MnO2, facilitating the deep oxidation of NOx. The facile realization of single atoms would be an ideal way to produce MOF-based catalysts with desired performance. Efficiently combining plasma with single atom-decorated MOF catalysts can provide additional prospects for the plasma-catalytic system.