Copper and silver are known to phase separate in bulk materials. Hence, bimetallic nanoparticles made of these metals offer a unique opportunity to synthetically control the stoichiometric composition and chemical ordering. There have been reports in the literature of the formation of either core-shell nanoparticles or bifacial heterodimers. However, due to the difficulties in performing elemental analysis on sub-10nm particles, no study presents a systematic treatment of how different morphologies can be accessed in a controlled manner. Here, we report a new room-temperature galvanic-exchange-based synthesis that allows access to the formation of several types of heterostructured Cu-Ag bimetallic nanoparticles, including both heterodimers and core-shell particles. Using STEM-EDS with highly-sensitive X-ray detectors, we are able to unambiguously identify the location of both metals with sub-nm precision. The role of post-synthetic oxidation has also been investigated with oxygen-free electron microscopy imaging.

Room-temperature formation of Cu-Ag bimetallic heterostructured nanocrystals via galvanic exchange

253rd National Meeting (2017)

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