The synthesis of metal nanostructures has received widespread attention owing to many important applications. We report the accelerated synthesis of nanoparticles (AuNPs) as well as the reducing-agent-free and template-free synthesis of nanowires in aerosol microdroplets at room temperature and atmospheric pressure (<i>Nat Comms</i>, in press). Figure 1a shows experimental setup for synthesizing nanostructures in microdroplets. At first, the AuNP synthesis are carried out by fusing two aqueous microdroplet streams containing chloroauric acid and sodium borohydride. AuNPs (~7 nm in diameter) are produced within 60 µs at the rate of 0.24 nm/µs. Compared to bulk solution, microdroplets enhance the size and growth rate of AuNPs by factors of about 2.1 and 1.2 x 10<sup>5</sup>, respectively. Later, we find that gold nanoparticles (Fig. 1b) and nanowires with ~7 nm width and &gt;2000 nm length (Fig. 1c) are also formed in microdroplets in the absence of any added reducing agent, template, or externally applied charge. This method also allows the synthesis of nanostructures from cobalt(II) sulfate and nickel(II) sulfate for electrocatalytic oxygen evolution reaction (OER) application. The microdroplet provides a new method for the accelerated growth of nanostructures by orders of magnitude as well as reducing-agent-free and template-free synthesis of metal nanostructures.

Reducing-agent-free and template-free synthesis of metal nanostructures in aqueous microdroplets

256th National Meeting (2018)

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