Baoji Hu

Study on the Anatase to Rutile Phase Transformation and Controlled Synthesis of Rutile Nanocrystals with the Assistance of Ionic Liquid

We developed a route to synthesize rutile TiO(2) nanocrystals (NCs) with the assistance of 1-butyl-3-methylimidazolium chloride (bmim(+)Cl(-)). The phase transformation from anatase to rutile phase was investigated, and a simple model to describe the phase transformation process was proposed considering that the nucleation and growth of rutile phase were determined by the aggregation manner of anatase NCs and Ostwald ripening process, respectively. It was demonstrated that the surfactant-like nature of the IL used was crucial for controlling the crystallization process via controlling the aggregation manner of the NCs. The phase, shape, and size of TiO(2) NCs could be tuned by the controlling the operating conditions, such as temperature, solution acidity, and reactant concentration of the bmim(+)Cl(-)/TiCl(4)/H(2)O reaction system. Phase-pure rutile multipods and 1D nanorods with different sizes were controllably obtained.

A simple route to coat mesoporous SiO2 layer on carbon nanotubes

Herein we present a simple method to coat a porous SiO2 layer on carbon nanotubes (CNTs) with the aid of the cationic surfactant cetyltrimethyl ammonium bromide (CTAB). The coating process was studied systematically, and a possible coating mechanism was proposed. Temperature and the ratio of CTAB/CNTs/H2O were found to play key role in the coating process. This method can be applied to both multiwalled carbon nanotubes (MWNTs) and single walled carbon nanotubes (SWNTs). The individualized nature of the CNTs (both MWNTs and SWNTs) was maintained during the coating process. Furthermore, Raman spectroscopy showed that this method is nondestructive to the electronic structure of CNTs. The CNT/porous SiO2 core/shell structure will serve as a platform for further surface functionalization of CNTs.

Shape controlled synthesis of palladium nanocrystals by combination of oleylamine and alkylammonium alkylcarbamate and their catalytic activity

The shape of Pd nanocrystals (NCs) can be controlled by combination of oleylamine (OAm) and alkylammonium alkylcarbamate (AAAC), and Pd spheres, tetrahedra and multipods have been synthesized. The multipods and tetrahedra are much more active than the spheres for hydrogenation reactions.

Shape and Size Controlled Synthesis of Anatase Nanocrystals with the Assistance of Ionic Liquid

We report an ionic liquid (IL) assisted hydrothermal method to synthesize anatase TiO(2) nanocrystals (NCs), in which TiCl(4) was used as precursor, 1-butyl-3-methylimidazolium chloride (bmim(+)Cl(-)) as IL, and F(-) or SO(4)(2-) ions as phase transformation inhibitor. The surfactant-like nature of IL was found to play a key role in controlling the crystallization process via controlling the aggregation manner of the NCs. The fine-tuning abilities of the operating parameters of the bmim(+)Cl(-)/TiCl(4)/H(2)O system facilitated the controlling over the shape and size of TiO(2) NCs. Phase-pure anatase monodisperse NCs with various shape and size were controllably obtained. Moreover, the aggregation manners of anatase NCs were also studied, and it was demonstrated that the high concentration of HF or H(2)SO(4) could result in aggregation of anatase NCs to form pseudo single crystals.

Cross-linked polymer coated Pd nanocatalysts on SiO2 support: very selective and stable catalysts for hydrogenation in supercritical CO2

Using greener solvents, enhancing the selectivity and stability of catalysts is an important aspect of green chemistry. In this work, we developed a route to immobilize Pd nanoparticles on the surface of silica particles with cross-linked polystyrene coating by one-step copolymerization, and Pd(0) nanocatalysts supported on the silica particle supports with cross-linked polystyrene coating were successfully prepared. The catalysts were characterized by Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), plasma optical emission spectroscopy, and thermogravimetric analysis (TGA), and were used for hydrogenation of 2,4-dimethyl-1,3-pentadiene to produce 2,4-dimethyl-2-pentene and allyl alcohol to produce 1-propanol. It was found that the selectivity of the reaction was enhanced significantly by the polymer coating, and the catalysts were very stable due to the insoluble nature of the cross-linked polymers. Supercritical (sc)CO2 can accelerate the reaction rates of the reactions catalyzed by the specially designed catalysts significantly. The excellent combination of polymer coating and scCO2 has wide potential applications in catalysis.