Unveiling the Nature of Room-Temperature O₂ Activation and O₂^•– Enrichment on MgO-Loaded Porous Carbons with Efficient H₂S Oxidation

Abstract

The activation of O2 into the dioxide radical (O2•–) at room temperature serves as a critical chemical process implicated in environmental remediation and industrial chemical processes, but the involved mechanism remains unclear. Herein, we address this challenge by the radical detection method combined with DFT study and unveil that the O2 activation reaction could take place merely in porous carbons (PCs) at room temperature. DFT calculations indicate that sp2-conjugated carbons can transfer a π* electron to the outer orbit of the O2 molecule derived by the space confinement in ultramicropores (∼0.4 nm), and the presence of edge site defects and heterogeneous atoms can facilitate the electron transfer due to increased quantity of free electrons. The produced O2•– radicals could be further trapped and enriched on the surface of MgO as predicted by DFT calculations, which is subsequently confirmed by radical detection analysis of the designed MgO-loaded PCs. Furthermore, the O2 activation and O2•– enrichment on MgO-loaded PCs are applied in a probe reaction of room-temperature catalytic H2S oxidation, in which an outstanding catalytic performance is achieved. These findings provide valuable insight into the intrinsic origin of the O2 activation at room temperature and open a fresh route to efficient formation and concentration of O2•– for aerobic oxidization processes.