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

Abstract

In an attempt to achieve the selective oxidation of NO x , 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 NO x 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 NO x . 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.

Synthesis, characterization and application of defective metal–organic frameworks: current status and perspectives

“…In addition to the introduction of NPs into the pores of defective MOFs, the organic linkers or metal nodes can also be used to anchor some species as active sites. 115,116,[125][126][127] Yaghi et al 39 synthesized a single-atom catalyst, Cu/UiO-66, through a covalent attachment of Cu atoms to the defect sites at zirconium oxide clusters (Fig. 11d).…”

In Situ Implanting of Single Tungsten Sites into Defective UiO‐66(Zr) by Solvent‐Free Route for Efficient Oxidative Desulfurization at Room Temperature

“…Single‐site catalysts (SSCs) with desired coordination environments and unique catalytic performance have become excellent candidates for various applications [19–22] . SSCs with catalytic sites at atomic‐scale and higher atom utilization, provide new opportunities to develop rational catalyst design for targeted reactions [23–26] . Owing to the remarkable stability, large surface area and rich coordination unsaturated sites, pristine MOFs are the prominent candidates for synthesizing SSCs [27–30] .…”

A Review of MOFs and Their Composites‐Based Photocatalysts: Synthesis and Applications

“…reported that the Ru‐NH 2 ‐Uio‐66/Mn composites photocatalysts were successfully synthesized by combining one‐step solution precipitation strategy with a solid mixed route. [ 113 ] As presented in Figure a, the Ru precursor and NH 2 ‐Uio‐66 were first mixed in DI water and stirred for 12 h to obtain Ru‐NH 2 ‐Uio‐66 composites; the MnO 2 was then combined with Ru‐NH 2 ‐Uio‐66 to prepare Ru‐NH 2 ‐Uio‐66/Mn composites photocatalysts through a solid mixed method. The TEM image (Figure 3b) shows the nanowire‐shaped and octahedral Ru‐NH 2 ‐Uio‐66/Mn composites.…”

“…Reproduced with permission. [ 113 ] Copyright 2020, American Chemical Society. c) Schematic illustration of the fabrication of Re n ‐MOF photocatalysts, and d,e) the SEM and TEM (inset) images of Re n ‐MOF photocatalysts.…”