Constructing MnO2 alpha/amorphous heterophase junction by mechanochemically induced phase transformation for formaldehyde oxidation

作者：Li, Xinyan; Chen, Muhua^*; Li, Guangyao; Wang, Ping^*

来源：Applied Surface Science, 2022, 589: 152855.

DOI：10.1016/j.apsusc.2022.152855

• Heterophase junction
• Phase transformation
• Mechanical milling
• Manganese dioxide-based catalyst
• Formaldehyde oxidation

Construction of heterophase junction has emerged as an effective approach for boosting the catalytic performance of diverse photoelectrocatalysts and electrocatalysts. But its potential in remediation of formaldehyde (HCHO) pollution was scarcely investigated. Herein, we report the fabrication, catalytic properties, and mechanistic study of alpha/A-MnO2 heterophase junction catalyst for HCHO oxidation. Our study found that mechanically milling delta-MnO2 could readily induce an delta to alpha phase transformation via an intermediate amorphous phase, thus providing a simple method for construction of MnO2 heterophase junction. The alpha/A-MnO2 catalyst prepared under the optimal condition exhibited an exceptionally high area specific reaction rate of 0.21 mu mol m(-2) min(-1) at 80 degrees C and excellent stability towards HCHO oxidation, outperforming most reported MnO2-based catalysts. Based on the in situ diffused reflectance infrared Fourier transform spectroscopy and on-line gas chromatography analyses, a possible mechanism was put forward to describe the synergistic catalysis effect between alpha-MnO2 and amorphous MnO2.