Abstract
Metal nanoparticles are widely used as catalysts due to their high activity. Due to their small size nanoparticles exhibit difficulty in separation and sintering. These issues can be overcome by supporting on a high surface area material. There are currently a number of problems associated with the use of supported nanoparticles, in particular their leaching into the environment.
In previous studies, confinement has been used to support nanoparticles inside a structure containing large interconnecting pores relative to the nanoparticle size. These pores allow the nanoparticles to flow through the support and leach into the environment. This project takes a novel approach of total encapsulation to supporting metal nanoparticles in a porous material. By total encapsulation it was anticipated this leaching could be prevented. Silica spheres offer a method to encapsulate metal nanoparticles as they have been reported to have well defined porous structures.
The template proved critical in the formation of silica spheres. It was found that a template with neutral charge could be used to form spheres with a higher surface area than when a cationic template was used. The use of an anionic template resulted in a high degree of organisation leading to the formation of a silica honeycomb. The activity of encapsulated nanoparticles was compared to those externally supported for the reduction of 4-nitrophenol. The leaching of silver nanoparticles was also investigated, and it was shown encapsulated nanoparticles had slightly reduced leaching. Not all of the spheres were complete, and this may be responsible for the observed leaching from the encapsulated silver.
In previous studies, confinement has been used to support nanoparticles inside a structure containing large interconnecting pores relative to the nanoparticle size. These pores allow the nanoparticles to flow through the support and leach into the environment. This project takes a novel approach of total encapsulation to supporting metal nanoparticles in a porous material. By total encapsulation it was anticipated this leaching could be prevented. Silica spheres offer a method to encapsulate metal nanoparticles as they have been reported to have well defined porous structures.
The template proved critical in the formation of silica spheres. It was found that a template with neutral charge could be used to form spheres with a higher surface area than when a cationic template was used. The use of an anionic template resulted in a high degree of organisation leading to the formation of a silica honeycomb. The activity of encapsulated nanoparticles was compared to those externally supported for the reduction of 4-nitrophenol. The leaching of silver nanoparticles was also investigated, and it was shown encapsulated nanoparticles had slightly reduced leaching. Not all of the spheres were complete, and this may be responsible for the observed leaching from the encapsulated silver.
| Original language | English |
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| Publication status | Published - Jul 2012 |