Synthesis Of Highly Dispersed Nanogold Catalyst And Various Metal Oxide Nanocrystals And Their Performance

Nanomaterials have attracted worldwide attention due to their unique properties and applications prospect. First at all, I have a review of nanomaterials, such as typical characteristics, preparation methods, and their characterization methods. Nanomaterials is still largely in the "discovery phase", wherein new materials are being synthesized on small scales (nanometers and microns) for testing properties, as well as their potential applications. Herein, I am exploring new ways to synthesize novel nanomaterials and test their relative applications.A nanoscale reactor framework of well-dispersed gold particles intercalated into the walls of mesoporous silica (GMS) was prepared by functionalizing silica with thioether groups. The GMS maintains mesoporous structure with uniform pores of 5.6 nm, and possesses high surface area of more than 800 m2·g-1 Moreover, the catalyst is very active for the reduction of p-nitrophenol (PNP) and methylene blue (MB) displaying catalytic activity in the reduction of PNP with Knor-PNP of 45.9 mmol-1·s-1. For reduction of MB, the catalytic rate of the catalyst decreases by less than 6% when recycled 10 times. Therefore, the nanoreactor framework catalyst is very robust and is readily separable and reusable, demonstrating attractive potential for practical applications. The unobstructed ordered mesoporous structure of the GMS catalyst and the small size of gold nanoparticles are the main factors leading to high catalytic activities.The preparations of gold gel and the syhthesis of nanoreactor which include gold nanoparticles were introduced in detail. Gold nanoparticles had been coated with amorphous silica to form spherical colloids with a core-shell structure. Monodisperse colloidal carbon microspheres were prepared from aqueous glucose solution by hydrothermal synthesis, and coated the carbon spheres with gold nanoparticles.Aerogel prepared CaO nanoparticles (AP-CaO) were introduced by a approach where methoxides were converted to hydroxide gels followed by hypercritical drying and vacuum dehydration. Calcium oxide obtained by this method had a surface area～120 m2/g. Studies had been investigated on removal of Congo red in aqueous solution using AP-CaO and commercial CaO (CM-CaO). The maximum adsorption capability of Congo red on AP-CaO and CM-CaO were 333.68 mg·g-1 and 201.32 mg·g-1 respectively. The pH, ionic strength, and temperature had very significant roles in affecting the Congo red adsorption capacity of CaO. Isotherm modeling revealed that the Langmuir equation could better describe the adsorption of dyes on the CaO as compared to other models. Kinetic data were approciately fitted with the pseudosecond-order adsorption rates. An summary of the adsorption capacibility of various metal oxide and mesoprous active carbon for Congo red was made to compared, and the order is:NiO< Cr2O3< MgO< CaO.