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.