Metal and metal oxide nanocrystals (NCs) are important materials for many applications, such as noble metals for heterogeneous catalysis, group IV elements for rechargeable batteries, and transitional metal oxide semiconductors for photovoltaics. Nanocrystals are typically synthesized via top-down or bottom-up methods. However, few syntheses integrate the advantages of both strategies. Here we report such a method, which is simple, generic, and of high atom and energy efficiency.  This method, entitled alternating voltage induced electrochemical synthesis (AVIES), has been demonstrated through the production of highly dispersed metal (Au, Pd, Pt, Sn, and Ag) and metal oxide (Ag2O, ZnO and TiO2) nanocrystals. The respective nanocrystals are produced when a zero-offset alternating voltage is applied to a pair of identical metal wires, which are inserted into an electrolyte solution containing capping ligands. Interestingly, the nanocrystals are formed on the electrode surfaces and not in the solution.  In the case of Au, the obtained nanocrystals are highly crystalline nano-icosahedra of 14 � 2 nm in diameter, the smallest Au icosahedra synthesized in aqueous solutions via green chemistry. Their catalytic activity has been demonstrated through facilitating the reduction of 4-nitrophenol to 4-aminophenol by sodium borohydride. This AVIES approach is an environmentally benign process and can be easily adopted by researchers.

Where top-down and bottom-up methods meet: An electrochemical synthesis of colloidal metal and metal oxide nanocrystals using alternating voltages

248th National Meeting (2014)

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