In situ liquid-cell electron microscopy of silver–palladium galvanic replacement reactions on silver nanoparticles

Abstract

Galvanic replacement reactions provide an elegant way of transforming solid nanoparticles into complex hollow morphologies. Conventionally, galvanic replacement is studied by stopping the reaction at different stages and characterizing the products ex situ. In situ observations by liquid-cell electron microscopy can provide insight into mechanisms, rates and possible modifications of galvanic replacement reactions in the native solution environment. Here we use liquid-cell electron microscopy to investigate galvanic replacement reactions between silver nanoparticle templates and aqueous palladium salt solutions. Our in situ observations follow the transformation of the silver nanoparticles into hollow silverpalladium nanostructures. While the silver-palladium nanocages have morphologies similar to those obtained in ex situ control experiments the reaction rates are much higher, indicating that the electron beam strongly affects the galvanic-type process in the liquid-cell. By using scavengers added to the aqueous solution we identify the role of radicals generated via radiolysis by high-energy electrons in modifying galvanic reactions.

Opportunities and challenges in liquid cell electron microscopy

“…However, existing knowledge of radiation physics can be a guide, and it has already been shown that electron-beam effects can be mitigated with scavenging strategies (43). As microscopists become increasingly familiar with beam effects in liquids, the low-dose techniques developed for biological cryo-electron microscopy are becoming standard, and the benefits of high-sensitivity detectors in reducing the dose required per image are being exploited.…”

Single-particle mapping of nonequilibrium nanocrystal transformations

“…Methods for the direct imaging of the evolution of individual nanoparticle species in a liquid environment are under active development because they enable the preservation of dynamic processes present in the native colloid (1,(8)(9)(10)(11)(12)(13)(14). Recently, our group has developed transmission electron microscopy (TEM) liquid cells based on the trapping of thin fluids between sheets of graphene ( Fig.…”

Bubble nucleation and migration in a lead–iron hydr(oxide) core–shell nanoparticle

“…Here, we made Pb-FeOOH core-shell nanoparticles in a liquid cell under transmission electron microscopy (TEM) (10)(11)(12). The iron hydroxide shell undergoes dehydration reaction upon electron irradiation and release gaseous species.…”