State Key Laboratory for Physical Chemistry of Solid Surfaces and Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China.
ACS Nano. 2012 May 22;6(5):4434-44. doi: 10.1021/nn3011703. Epub 2012 Apr 22.
The design and synthesis of hollow/yolk-shell mesoporous structures with catalytically active ordered mesoporous shells can infuse new vitality into the applications of these attractive structures. In this study, we report that hollow/yolk-shell structures with catalytically active ordered mesoporous aluminosilica shells can be easily prepared by using silica spheres as the silica precursors. By simply treating with a hot alkaline solution in the presence of sodium aluminate (NaAlO(2)) and cetyltrimethylammonium bromide (CTAB), solid silica spheres can be directly converted into high-quality hollow mesoporous aluminosilica spheres with perpendicular pore channels. On the basis of the proposed formation mechanism of etching followed by co-assembly, the synthesis strategy developed in this work can be extended as a general strategy to prepare ordered mesoporous yolk-shell structures with diverse compositions and morphologies simply by replacing solid silica spheres with silica-coated nanocomposites. The reduction of 4-nitrophenol with yolk-shell structured Au@ordered mesoporous aluminosilica as the catalyst has clearly demonstrated that the highly permeable perpendicular pore channels of mesoporous aluminosilica can effectively prevent the catalytically active yolk from aggregating. Furthermore, with accessible acidity, the yolk-shell structured ordered mesoporous aluminosilica spheres containing Pd yolk exhibit high catalytic activity and recyclability in a one-pot two-step synthesis involving an acid catalysis and subsequent catalytic hydrogenation for desired benzimidazole derivative, which makes the proposed hollow ordered aluminosilica spheres a versatile and practicable scaffold for advanced catalytic nanoreactor systems.
具有催化活性的有序介孔壳的中空/蛋黄壳介孔结构的设计和合成可为这些有吸引力的结构的应用注入新的活力。在本研究中，我们报告了具有催化活性的有序介孔硅铝酸盐壳的中空/蛋黄壳结构可以很容易地通过使用二氧化硅球作为硅源前驱体制备。通过在含有偏铝酸钠（NaAlO(2)）和十六烷基三甲基溴化铵（CTAB）的热碱性溶液中简单处理，固体二氧化硅球可以直接转化为具有垂直孔道的高质量中空介孔硅铝酸盐球。基于提出的刻蚀后共组装的形成机制，本工作中开发的合成策略可以通过用包覆有二氧化硅的纳米复合材料替代固体二氧化硅球而扩展为一种通用策略，以简单地制备具有不同组成和形貌的有序介孔蛋黄壳结构。用作为催化剂的具有蛋黄壳结构的 Au@有序介孔硅铝酸盐还原 4-硝基苯酚，清楚地表明介孔硅铝酸盐的高渗透性垂直孔道可以有效地阻止催化活性的蛋黄聚集。此外，具有可及酸度的含钯蛋黄的蛋黄壳结构有序介孔硅铝酸盐球在一锅两步合成中表现出高催化活性和可回收性，其中包括酸催化和随后的催化加氢，用于所需的苯并咪唑衍生物，这使得所提出的中空有序硅铝酸盐球成为用于先进催化纳米反应器系统的多功能和实用支架。
