Peptide stabilized Ag@ Au Core- shell Nanoparticles: Synthesis, Variation of Shell Thickness, and Catalysis

Ag@Au core-shell nanoparticles were synthesized by using a fluorescent dipeptide -Ala-Trp in water medium and at a room temperature without using any external reducing and stabilizing agents. The shell thickness of gold in core-shell Ag@Au nanoparticles has also been varied by changing the concentration of the gold(III) precursor keeping the other conditions same. The optical property of these core-shell nanoparticles varies with the shell thickness. Interestingly, these core-shell nanoparticles exhibit good catalytic property for the reduction of nitrophenols to aminophenols and nitroanilines to aminoanilines. A series of nitrophenol and nitroaniline compounds were taken as substrates for reduction. Moreover, this core-shell nanoparticle displays remarkable difference in catalytic property for reduction of nitro group with the variation of shell thickness. This catalyst (Ag@Au core-shell nanoparticle) can also be recycled for several times indicating its reusability.