Mechanistic Insights into Oxygen Dynamics in Soot Combustion over Cryptomelane Catalysts in Tight and Loose Contact Modes via ¹⁸O₂/¹⁶O₂ Isotopic Variable Composition Measurements – A Hot Ring Model of the Catalyst Operation

A cryptomelane K-OMS-2 model catalyst of a well-defined nanorod morphology, dominated by the (100) and (110) planes, was synthesized, thoroughly examined means XRD, Raman, XPS, XAS, TEM/EDX/SAED, computed X-ray microtomography techniques. The oxidation performance elucidated in tight (TC) loose (LC) contact modes using isotopic 18O2/16O2 mixtures various compositions. simple methodology disentangling relative involvement suprafacial (adsorbed/gas phase) intrafacial (surface/lattice) reactive oxygen species soot developed, allowing for straightforwardly unraveling mechanistic details LC TC combustion particles. functional “hot ring model” established to rationalize operation. It found that apart from ROS generation function, acts mode as an igniter, whereas booster drives process until afterburning stage is reached. obtained results were accounted molecular DFT atomistic thermodynamic modeling, justifying particular role surface di- (O2c) tri-coordinated (O3c) anions, located on planes nanorods, ignition process.