Lu Yuqin, Deng Hua, Pan Tingting, Zhang Changbin, He Hong
Center for Excellence in Regional Atmospheric Environment, Key Laboratory of Urban Pollutant Conversion, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China.
University of Chinese Academy of Sciences, Beijing 100049, China.
ACS Appl Mater Interfaces. 2023 Feb 22;15(7):9362-9372. doi: 10.1021/acsami.2c21120. Epub 2023 Feb 8.
Catalytic ozonation has gained considerable interest in volatile organic compound (VOC) elimination due to its mild reaction conditions. However, the low activity and mineralization rate of VOCs over catalysts hinder its practical application. Herein, a series of α-MnO nanowire catalysts were prepared via thermal annealing treatment at various temperatures to tailor defect species. Numerous characterization techniques were used and combined to investigate the relationship between activity and microstructure. PALS and XAFS indicated that more unsaturated manganese and oxygen vacancies, especially surface oxygen vacancy clusters, were produced in α-MnO under the optimal high calcination temperature. As a result, MnO-600 was found to exhibit the best-ever performance in toluene conversion (95%) and mineralization rate (89.5%) at 20 °C, making it a promising candidate for practical use. The roles of these defects in manipulating the reactive oxygen species of α-MnO were clarified by quantifying the amounts of reactive oxygen species by quenching experiments and density functional theory calculations. O and ·OH species generated in the vicinity of oxygen vacancy clusters, especially the dimer oxygen vacancy cluster, were identified as key oxygen species in the abatement of toluene. This study provides a facile method to engineer the microstructure of MnO by means of the manipulation of oxygen vacancies and an in-depth understanding of their roles in the catalytic ozonation of VOC.
催化臭氧化由于其温和的反应条件，在挥发性有机化合物（VOC）消除方面引起了广泛关注。然而，催化剂上VOC的低活性和矿化率阻碍了其实际应用。在此，通过在不同温度下进行热退火处理制备了一系列α-MnO纳米线催化剂，以调整缺陷种类。使用并结合了多种表征技术来研究活性与微观结构之间的关系。正电子湮没寿命谱（PALS）和X射线吸收精细结构（XAFS）表明，在最佳的高煅烧温度下，α-MnO中产生了更多的不饱和锰和氧空位，特别是表面氧空位簇。结果发现，MnO-600在20℃下的甲苯转化率（95%）和矿化率（89.5%）方面表现出有史以来最好的性能，使其成为实际应用的有前途的候选者。通过猝灭实验和密度泛函理论计算对活性氧物种的量进行定量，阐明了这些缺陷在操纵α-MnO的活性氧物种中的作用。在氧空位簇附近，特别是二聚体氧空位簇处产生的O和·OH物种被确定为甲苯消除中的关键氧物种。本研究提供了一种通过操纵氧空位来设计MnO微观结构的简便方法，并深入了解了它们在VOC催化臭氧化中的作用。
