Revealing the key role of interfacial oxygen activation over CoMn₂O₄@MnO₂ in the catalytic oxidation of acetone

The accumulation of intermediate products on the catalyst surface caused by insufficient oxygen activity is an important reason for the poor activity of catalysts towards oxygenated volatile organic compounds (OVOCs). CoMn₂O₄@MnO₂ heterogeneous catalysts were fabricated to decipher the interfacial oxygen activation mechanism for efficient acetone oxidation. Experimental and theoretical explorations revealed that oxygen vacancies were easily formed at the interface. Gaseous oxygen tended to adsorb on the interfacial vacancies while bonding with adjacent Mn sites, resulting in the stretching of O-O bonds. Rapid electron transfer at the interface led to the charge accumulation on the two oxygen atoms inducing electrostatic repulsion. These factors are conducive to the O-O bond breaking and gaseous oxygen activation. The obtained CoMn₂O₄@0.8MnO₂ exhibited excellent catalytic performance with 90 % of acetone conversion at 159 °C, better than CoMn₂O₄ and MnO₂. The acetone oxidation on CoMn₂O₄@0.8MnO₂ not only avoided the accumulation of aldehydes, but also realized the rapid degradation of acetate into formate, achieving the shortest degradation pathway due to the rapid interfacial oxygen activation. CoMn₂O₄@0.8MnO₂ also exhibited better catalytic activity for other OVOCs (ethyl acetate, ethylene oxide, methanol). This work provides new insights for the mechanism of interfacial oxygen activation and the design of heterogeneous catalyst for efficient OVOC oxidation.