(264h) Highly Crystalline Mesoporous TiO2 Composed Of Oriented Nanorod Building Blocks

TiO2 is one of the most important electronic, optical, catalytic, and photocatalytic materials, and has been subject to intensive study for a variety of applications such as novel support of gold nanocatalysts, semiconductor charge carrier in dye sensitized solar cells, and new electrodes for energy storage in high performance batteries. A key challenge for such applications is achieving stable, high surface area, high quality nanocrystalline structures. Great efforts have been made to synthesize high surface area mesoporous TiO2 using surfactant templating routes. Such mesoporous TiO2 typically has amorphous, semicrystalline or nanocrsytalline wall structures.

Here we report a novel approach to grow and assemble one-dimensional rod-like TiO2 nanocrystals into aligned mesostructures with thermally stable, tunable mesoporosity. Organic matrix mediated nucleation and growth of oriented three-dimensional nanostructures is an important phenomenon in biominerals, but remains a significant challenge in synthetic materials. We used a surfactant matrix to simultaneously control the crystalline phase, orientation, and spatial arrangement, and produced a new class of highly crystalline mesoporous TiO2 based on aligned rutile rod-like nanocrystals, a drastic departure from traditional mesoporous TiO2 containing randomly oriented anatase. X-ray diffraction (XRD) patterns and N2 sorption isotherms reveal mesoporous structure in the highly crystalline mesoporous TiO2 directly results from anionic surfactant templating effects with high surface area (245~300 m2/g) and tunable pore diameter ranging from 2.2 to 3.8 nm. Transmission electron microscopy (TEM) measurements show that framework of the highly crystalline mesoporous TiO2 are composed of aligned rutile rod-like nanocrystals grown along [001] direction. Such stable, highly crystalline nanoporous materials are expected as a good candidate of stable catalyst support or used in many other applications.