Angshuman Pal

Preparation of Silver–Gold Alloy Nanoparticles at Higher Concentration Using Sodium Dodecyl Sulfate

Highly stable gold–silver alloy nanoparticles with varying mole fractions were prepared in aqueous sodium dodecyl sulfate solution by simultaneous reduction of chloroauric acid (HAuCl4) and silver nitrate (AgNO3) using sodium citrate. The formation of alloy nanoparticles was confirmed by UV-visible spectroscopy and transmission electron microscopy. Particle size distribution was measured by dynamic light scattering. The surface plasmon absorption band of the Au–Ag alloy nanoparticles shows linear bathochromic shift with increasing Au content. Appearance of a single absorption peak in the visible region and lack of apparent core-shell structures in the transmission electron microscope images confirm the formation of homogeneous gold–silver alloy nanoparticles.

Formation and Stabilization of Anisotropic Palladium and Platinum Nanoparticles in Aqueous Polymer Solution Using Microwave Irradiation

Anisotropic palladium and platinum nanoparticles were synthesized by reduction of the corresponding metal ions with hydrazine using polyacrylamide as a stabilizing agent in aqueous medium under microwave irradiation. The formation of particles was confirmed by UV-visible spectroscopy. The size and shape of the particles were determined using transmission electron microscopy. Rapid microwave heating resulted in ‘star-shaped’ palladium nanoparticles, but platinum nanoparticles were observed to be spherical with a distinctly visible 3–4 nm coating of polyacrylamide on their surface, which was not observed for the palladium particles. The Pt nanoparticles were used as a catalyst in the redox reaction.