State Key Lab of Urban Water Resource and Environment, School of Civil and Environmental Engineering, Harbin Institute of Technology Shenzhen, Shenzhen, 518055, P. R. China.
Department of Materials Science and Engineering, City University of Hong Kong, 83 Tat Chee Avenue, Kowloon, Hong Kong, 999077, P. R. China.
Small. 2021 Dec;17(50):e2103052. doi: 10.1002/smll.202103052. Epub 2021 Oct 31.
Manganese dioxide (MnO ), with naturally abundant crystal phases, is one of the most active candidates for toluene degradation. However, it remains ambiguous and controversial of the phase-activity relationship and the origin of the catalytic activity of these multiphase MnO . In this study, six types of MnO with crystal phases corresponding to α-, β-, γ-, ε-, λ-, and δ-MnO are prepared, and their catalytic activity toward ozone-assisted catalytic oxidation of toluene at room temperature are studied, which follow the order of δ-MnO > α-MnO > ε-MnO > γ-MnO > λ-MnO > β-MnO . Further investigation of the specific oxygen species with the toluene oxidation activity indicates that high catalytic activity of MnO is originated from the rich oxygen vacancy and the strong mobility of oxygen species. This work illustrates the important role of crystal phase in determining the oxygen vacancies' density and the mobility of oxygen species, thus influencing the catalytic activity of MnO catalysts, which sheds light on strategies of rational design and synthesis of multiphase MnO catalysts for volatile organic pollutants' (VOCs) degradation.
二氧化锰（MnO ）具有丰富的晶体相，是甲苯降解最活跃的候选物之一。然而，这些多相 MnO 的相-活性关系和催化活性的起源仍然存在模糊和争议。在本研究中，制备了六种具有对应于 α-、β-、γ-、ε-、λ-和 δ-MnO 晶体相的 MnO ，并研究了它们在室温下对臭氧辅助催化氧化甲苯的催化活性，其顺序为 δ-MnO ＞α-MnO ＞ε-MnO ＞γ-MnO ＞λ-MnO ＞β-MnO 。对具有甲苯氧化活性的特定氧物种的进一步研究表明，MnO 的高催化活性源于丰富的氧空位和氧物种的强迁移率。这项工作说明了晶体相在决定氧空位密度和氧物种迁移率从而影响 MnO 催化剂的催化活性方面的重要作用，这为设计和合成用于挥发性有机污染物（VOCs）降解的多相 MnO 催化剂提供了策略。
