Catalytic oxidation of formaldehyde by MnOx-decorated anatase TiO2{001}: Investigation of the effect of calcination temperature on catalytic activity and reaction mechanism

The removal of indoor formaldehyde (HCHO) is crucial for human health. The design of highly catalytically active nonprecious metal catalysts has major challenges, and the use of transition metal element modification to improve the catalytic performance is an effective strategy. In this study, the active component Mn was loaded on highly active crystalline anatase TiO 2 {001}, and the effect of the calcination temperature on the catalytic activity was investigated. The important influence of temperature on the catalyst valence distribution, surface active oxygen species, and content was thoroughly determined by characterization techniques, such as XPS , H 2 -TPR, and O 2 -TPD. The catalytic reaction process was further analyzed by in situ infrared technology to determine the reaction intermediates and to clarify the catalyst reaction poisoning mechanism; additionally, a reasonable HCHO catalytic reaction pathway was proposed with the combination of density function theory calculations. In addition, oxygen defects on the catalyst surface were determined by EPR , and based on theoretical calculations, the oxygen defects could further reduce the reaction energy barrier through the Langmuir-Hinshelwood mechanism. By exposing specific crystal surfaces and increasing the number of oxygen defects, the catalytic activity could be effectively improved; based on these results, our study provides a concept for the subsequent development of nonprecious metal catalysts.