Hou Jingtao, Li Yuanzhi, Mao Mingyang, Zhao Xiujian, Yue Yuanzheng
State Key Laboratory of Silicate Materials for Architectures (Wuhan University of Technology), 122 Luoshi Road, Wuhan 430070, P. R. China.
Nanoscale. 2014 Dec 21;6(24):15048-58. doi: 10.1039/c4nr04142a. Epub 2014 Nov 4.
The nanostructure of Ce doped OMS-2 plays a very important role in its catalytic property. We demonstrate by density functional theory (DFT) calculations that the unique nanostructure of the Ce ion substituted OMS-2 with Mn vacancy in the framework is beneficial for the improvement of catalytic activity, while the nanostructure of the Ce ion substituted OMS-2 without defects are detrimental to the catalytic activity. We establish a novel and facile strategy of synthesizing these unique Ce ion substituted OMS-2 nanostructure with Mn vacancies in the framework by hydrothermal redox reaction between Ce(NO3)3 and KMnO4 with KMnO4/Ce(NO3)3 at a molar ratio of 3 : 1 at 120 °C. Compared to pure OMS-2, the produced catalyst of Ce ion substituted OMS-2 ultrathin nanorods exhibits an enormous enhancement in the catalytic activity for benzene oxidation, which is evidenced by a significant decrease (ΔT(50) = 100 °C, ΔT(90) = 129 °C) in the reaction temperature of T50 and T90 (corresponding to the benzene conversion = 50% and 90%), which is considerably more efficient than the expensive supported noble metal catalyst (Pt/Al2O3). We combine both theoretical and experimental evidence to provide a new physical insight into the significant effect due to the defects induced by the Ce ion substitution on the catalytic activity of OMS-2. The formation of unique Ce ion substituted OMS-2 nanostructure with Mn vacancies in the framework leads to a significant enhancement of the lattice oxygen activity, thus tremendously increasing the catalytic activity.
铈掺杂的OMS-2的纳米结构在其催化性能中起着非常重要的作用。我们通过密度泛函理论（DFT）计算表明，框架中具有锰空位的铈离子取代的OMS-2的独特纳米结构有利于催化活性的提高，而无缺陷的铈离子取代的OMS-2的纳米结构则对催化活性不利。我们通过在120℃下，使硝酸铈（Ce(NO3)3）与高锰酸钾（KMnO4）以KMnO4/Ce(NO3)3摩尔比为3:1进行水热氧化还原反应，建立了一种新颖且简便的合成框架中具有锰空位的独特铈离子取代的OMS-2纳米结构的策略。与纯OMS-2相比，所制备的铈离子取代的OMS-2超薄纳米棒催化剂在苯氧化催化活性方面有极大提高，这通过T50和T90（对应苯转化率为50%和90%）反应温度的显著降低（ΔT(50)=100℃，ΔT(90)=129℃）得以证明，其效率远高于昂贵的负载型贵金属催化剂（Pt/Al2O3）。我们结合理论和实验证据，对铈离子取代引起的缺陷对OMS-2催化活性的显著影响提供了新的物理见解。框架中具有锰空位的独特铈离子取代的OMS-2纳米结构的形成导致晶格氧活性显著增强，从而极大地提高了催化活性。
