Preparation And Catalytic Performance Of Novel Carbon Supported Noble Metal Nanoparticles

Noble metal nanoparticles have attracted more and more attention for their prominent properties such as Surface Enhanced Raman Scattering(SERS),catalysis,pharmaceuticals and so on.In this paper,impregnation method was employed to absorb noble metal gold and platinum onto fresh eggshell membranes.Then the noble metal was reduced by the reducing gases released from the pyrolysis of eggshell membranes under nitrogen protection environment.The as-obtained black samples were Au/C and Pt/C catalyst and the nanoparticles were dispersed well on the substrates.The samples were characterized by XRD,FESEM,TEM,XPS,FTIR and UV-vis-DRS.The main works achieved were as follows:1.Chloroauric acid was chosen as gold source and was prepared as ethanol solution.Fresh eggshell membranes were soaked in appropriate solution till the color of the solution faded gradually.The black samples after carbonization were Au/C catalyst.In this material,the gold nanoparticles were diapersed well on the carbon substrates and the diameters were ranging from 2 to 6 nm.This catalyst was found to be effective and recyclable for the coupling reaction of bromobenzene and aniline.The substrate was the key factor of the stability.When the carbonization temperature rised to 1000℃,the structure of substrate was destroyed and the gold nanoparticles aggregated to bulk gold,leading to the considerable reduction of catalytic property.2.The synthesis process of Pt/C catalyst was the same as Au/C,with the gold source replaced by platinum source.From the images of TEM,it could be seen that the platinum nanoparticles were also dispersed well on the eggshell membranes and the diameters of the particles were ranging from 5 to 8 nm.The as-prepared catalyst was excellent catalyst for aerobic oxidation of benzyl alcohol and the selectivity of benzaldehyde could be 99.9%.Because the surface plasmon resonance effect of noble metal nanoparticles,the photocatalysis of this reaction was also investigated.The results showed that both Pt/C and Au/C catalysts had very good photocatalytic activity for the reaction and the selectivity of benzaldhyde was high.When the diameter of nanoparticles were very small,the activity was increasing with the increase of noble metal loading.