Femtoliter Batch Reactors for Nanofluidic Scattering Spectroscopy Analysis of Catalytic Reactions on Single Nanoparticles

Abstract: Macroscopic batch reactors are a core concept in chemical synthesis and catalysis due to their ability to ensure high conversion rates of the used reactants. At the nanoscale, such reactors hold promise due to their potential to enable chemistry in confinement under well-controlled mass transport conditions, and as enablers for the characterization of catalytic reactions on tiny active surface areas, such as single nanoparticles. However, their practical implementation and the readout of reaction products if used for the study of catalytic reactions is challenging due to their tiny volume and the requirement of being able to transiently open and close such nanoscopic batch reactors. Here, we introduce a liquid phase nanofluidic batch reactor concept with a volume of 4.8 femtoliters that conveniently can be opened and closed using a bypassing N2 gas stream, and that in combination with nanofluidic scattering spectroscopy readout enables the characterization of a catalytic reaction on a single nanoparticle inside the reactor, as we demonstrate on the catalytic reduction of fluorescein by sodium borohydride on a Au catalyst.