Traditional synthetic methods of preparing monodisperse, supported nanoparticles remain problematic. Classical methods typically require organic surfactants to passivate the nanoparticle surface to limit undesired size changes. Calcination is generally required following the deposition of the nanoparticles on to a support material to remove the surfactant and activate the catalyst. Exposure to high temperatures during calcination results in significant and unpredictable growth of the nanoparticles, undoing the monodispersity achieved during synthesis.  The undesired growth of the nanoparticles decreases the total surface area available for catalysis ultimately reducing the activity of the catalyst. In this work, we present the use of switchable surfactants (SwiS) for the preparation of monodisperse, sinter-resistant, supported nanoparticle catalysts. SwiS are molecules that undergo reversible, physical changes in response to an external stimulus. The SwiS can be “turned-on” to template nanoparticles during synthesis and then “turned-off” to release the nanoparticles. The templating synthesis via a hypothesized reverse-micelle formation allows for the production of monodisperse nanoparticles.  Nanoparticle size has shown to increase as the alkyl chain length of the SwiS is increased. The template is disassembled by “turning off” the SwiS using gentle heat exposing surface-clean nanoparticles for deposition on to a catalyst support. The deposition of bare nanoparticles allows for the formation of a highly active catalyst that does not require activation via calcination, thus, maintaining monodispersity as shown by transmission electron microscopy. Supported gold nanoparticles prepared using SwiS are up to 300% more active in the hydrogenation of 4-nitrophenol than their traditionally prepared counter-parts and exhibit a significant resistance to nanoparticle sintering at high temperatures.<br/>

Switchable surfactants for the preparation of monodisperse, sinter-resistant supported nanoparticles

255th National Meeting (2018)

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