Platinum (Pt) and platinum-rhodium (PtRh) nanoparticles (NPs) are active catalysts for a range of important industrial reactions, and their response has been shown to be affected by size, morphology, composition, and architectural configuration. We report herein the engineering of these functionalities into NPs by suitably modifying our single-step fabrication process by using microwave irradiation dielectric heating. NPs with different morphologies are acquired by manipulating the reaction kinetics with the concentration of the capping agent while keeping the reaction time constant. Pt@Rh core@shell octopod-cube, Pt-truncated-cube, and cube and small-sphere NPs having "near-monodisperse" distributions and average sizes in the range of 4 to 18 nm are obtained. By increasing the microwave time the composition of Pt@Rh can be tuned, and NPs with a Rh-rich shell and a tunable Pt100-x Rh x (x≤41 at %) core are fabricated. Finally, alloy bimetallic PtRh NPs with controlled composition are designed by simultaneous tuning of the relative molar ratio of the metal precursors and the microwave irradiation time.
Keywords: alloys; microwave chemistry; nanoparticles; platinum; rhodium.