Zhao Pei, Lu Zhansheng, Liu Shantang
Key Laboratory for Green Chemical Process of Ministry of Education, School of Chemistry and Environmental Engineering, Wuhan Institute of Technology, Wuhan 430074, China.
College of Physics and Electronic Engineering, Henan Normal University, Xinxiang, 453007, China.
J Nanosci Nanotechnol. 2018 May 1;18(5):3348-3355. doi: 10.1166/jnn.2018.14660.
Manganese oxide (MnOx) supported on CeO2 nanocubes (MnOx/CeO2) were synthesized and tested for the catalytic combustion of chlorobenzene (CB), which was taken as a model compound of chlorinated volatile organic compounds (CVOCs). The catalytic activity tests demonstrated that MnOx/CeO2 nanocube catalysts exhibited a catalytic activity significantly better than that of bare CeO2 nanocubes, indicating MnOx plays a significant role for CB oxidation. To illustrate the effect of MnOx on the CeO2 nanocubes, experimental and theoretical methods such as density functional theory (DFT) calculations were carried out. Experimental characterization testified that the introduction of MnOx to CeO2 nanocubes brought the facile reduction of cerium species, larger amount of Oα species and oxygen vacancies, which lead to the enhanced catalytic performance of MnOx/CeO2 nanocube. Furthermore, DFT calculations clearly validated that MnOx/CeO2 (100) models could form the oxygen vacancies more easily, and CB molecules were preferentially adsorbed on the MnOx/CeO2 (100) models than on the CeO2 (100) models, which facilitated the easier formation of C-O* bond; this facile bond formation enabled faster CB decomposition into COx, thereby a higher CB conversion on the MnOx/CeO2 (100) could be found. Therefore, the vital role of MnOx can be successfully elucidated by both experimental and theoretical methods. Hence, this finding can be utilized for enhanced catalytic performance of CeO2 nanocube catalysts for the CVOCs elimination.
合成了负载在CeO₂纳米立方体上的氧化锰（MnOx/CeO₂），并测试了其对氯苯（CB）的催化燃烧性能，氯苯被用作氯代挥发性有机化合物（CVOCs）的模型化合物。催化活性测试表明，MnOx/CeO₂纳米立方体催化剂的催化活性明显优于裸露的CeO₂纳米立方体，这表明MnOx在CB氧化中起着重要作用。为了阐明MnOx对CeO₂纳米立方体的影响，采用了密度泛函理论（DFT）计算等实验和理论方法。实验表征证明，向CeO₂纳米立方体中引入MnOx会使铈物种易于还原，产生更多的Oα物种和氧空位，从而提高了MnOx/CeO₂纳米立方体的催化性能。此外，DFT计算清楚地证实，MnOx/CeO₂(100)模型更容易形成氧空位，并且CB分子在MnOx/CeO₂(100)模型上比在CeO₂(100)模型上更优先吸附，这有利于更容易形成C-O*键；这种容易的键形成使CB更快地分解为COx，因此在MnOx/CeO₂(100)上可以发现更高的CB转化率。因此，通过实验和理论方法都可以成功阐明MnOx的重要作用。因此，这一发现可用于提高CeO₂纳米立方体催化剂对CVOCs的消除催化性能。
