Core-shell nanocrystals have attracted increased interests owing to their wide applications in areas such as bioimaging, drug delivery, catalysis, electronics and photonics. On the other hand, atomically dispersed alloy often exhibits dramatic properties due to the synergistic effect and atomic geometry. Therefore, synthesis of core-shell structures with atomically dispersed alloy shell is of great interests. However, it remains a great challenge. Maneuvering growth kinetics is an effective method for synthesizing highly dispersed alloy with various shape and ratio of components. Herein, we report the controlled synthesis of the core-shell structured nanoparticles with a gold core and atomically dispersed alloy shell of palladium and silver (Au@PdAg NPs) by manipulating growth kinetics. To this end, we at first developed an analytical method to measure the growth kinetics of AgPd alloy shell with high temporal resolution by on-line coupling size-exclusion chromatography (SEC) with inductively coupled plasma mass spectrometry (ICP-MS), an effective method for separation and quantification of ions and nanocrystals. To facilitate the SEC-ICP-MS determination, we developed an Ag and Pd growth quencher, which consists of surfactant 1% (v/v) FL-70, 0.01% (v/v) Triton X-114 and 200 μmol/L Na2S2O3, and is able to protected Au@AgPd NPs from dissolution or further reduction in 5 hours. With this developed analytical method, we then precisely measured the growth rate of Pd and Ag, respectively. Finally, based on the growth rate of Pd and Ag, the growth rate of Pd was quantitatively manipulated by controlling the addition speed of H2PdCl4 into the reaction solutions with a syringe pump, which facilitates the formation of atomically dispersed AgPd alloy shell with different ratios. Our method provides a powerful technique for synthesis of core-shell structures with atomically dispersed alloy shell.

Controlled synthesis of atomically dispersed alloy shell of Au@PdAg nanoparticles by manipulating growth kinetics

255th National Meeting (2018)

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