One-pot, seedless synthesis of flowerlike Au-Pd bimetallic nanoparticles with core-shell-like structure via sodium citrate coreduction of metal ions

Bimetallic nanoparticles (NPs) comprised of gold (Au) and palladium (Pd) are promising catalysts in accelerating a variety of chemical reactions. The further performance enhancement greatly depends on the current efforts to create the synthetic methodology for optimizing NP morphology and structure. Here we report a one-pot and seedless synthesis of Au-Pd bimetallic NPs via citrate coreduction of Au and Pd ions. Due to the higher capacity of citrate in reducing Au ions, the nucleation of Au NPs is more favored than that of Pd. Consequently, the current system permits the production of bimetallic NPs with core-shell-like structure, namely an Au-rich core and Pd-rich shell. Moreover, the morphology of the as-synthesized NPs is also determined by the experimental variables, such as the Au-to-Pd feed ratio, dosage of sodium citrate, and charging sequence. With a good control of the nucleation and growth process, flowerlike Au-Pd bimetallic NPs with core-shell-like structures are synthesized. These flowerlike bimetallic NPs are the best in catalyzing formic acid oxidation and Suzuki coupling reaction in comparison to the Au-Pd bimetallic NPs with other morphologies.