Department of Chemistry, Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Laboratory of Advanced Materials, iChEM (Collaborative Innovation Center of Chemistry for Energy Materials), Fudan University , Shanghai 200433, China.
Department of Chemistry, University of California , Berkeley, California 94720, United States.
J Am Chem Soc. 2017 Jan 11;139(1):517-526. doi: 10.1021/jacs.6b11641. Epub 2016 Dec 21.
Constructing three-dimensional (3-D) hierarchical mesostructures with unique morphology, pore orientation, single-crystal nature, and functionality remains a great challenge in materials science. Here, we report a confined microemulsion self-assembly approach to synthesize an unprecedented type of 3-D highly ordered mesoporous TiO superstructure (Level-1), which consists of 1 spherical core and 12 symmetric satellite hemispheres epitaxially growing out of the core vertices. A more complex and asymmetric TiO superstructure (Level-2) with 13 spherical cores and up to 44 symmetric satellite hemispheres can also be well manipulated by increasing the size or content of impregnated TiO precursor emulsion droplets. The obtained 3-D mesoporous TiO superstructures have well-defined bouquet-posy-like topologies, oriented hexagonal mesochannels, high accessible surface area (134-148 m/g), large pore volume (0.48-0.51 cm/g), and well single-crystalline anatase walls with dominant (001) active facets. More interestingly, all cylindrical mesopore channels are highly interconnected and radially distributed within the whole superstructures, and all TiO nanocrystal building blocks are oriented grown into a single-crystal anatase wall, making them ideal candidates for various applications ranging from catalysis to optoelectronics. As expected, the bouquet-posy-like mesoporous TiO superstructure supported catalysts show excellent catalytic activity (≥99.7%) and selectivity (≥96%) in cis-semihydrogenation of various alkynes, exceeding that of commercial TiO (P25) supported catalyst by a factor of 10. No decay in the activity was observed for 25 cycles, revealing a high stability of the mesoporous TiO superstructure supported catalyst.
构建具有独特形貌、孔取向、单晶性质和功能的三维（3-D）分层介观结构仍然是材料科学中的一大挑战。在这里，我们报告了一种受限微乳液自组装方法，用于合成一种前所未有的 3-D 有序介孔 TiO 超结构（一级），它由 1 个球形核和 12 个对称卫星半球从核顶点外延生长而成。通过增加浸渍 TiO 前驱体乳液液滴的尺寸或含量，还可以很好地操纵更复杂和不对称的 TiO 超结构（二级），其具有 13 个球形核和多达 44 个对称卫星半球。所得的 3-D 介孔 TiO 超结构具有明确的花束状拓扑结构、取向的六方介孔、高可及表面积（134-148 m/g）、大孔体积（0.48-0.51 cm/g）和具有主导（001）活性面的单晶锐钛矿壁。更有趣的是，所有的圆柱介孔通道在整个超结构内高度互连并呈放射状分布，所有 TiO 纳米晶构建块都定向生长成单晶锐钛矿壁，使它们成为从催化到光电的各种应用的理想候选材料。不出所料，花束状介孔 TiO 超结构负载的催化剂在各种炔烃的顺式半氢化反应中表现出优异的催化活性（≥99.7%）和选择性（≥96%），超过商业 TiO（P25）负载催化剂的 10 倍。在 25 个循环中没有观察到活性衰减，表明介孔 TiO 超结构负载的催化剂具有高稳定性。
