Laser fragmentation in liquids (LFL) allows the synthesis of fully inorganic, ultrasmall gold nanoparticles, usAu NPs (<3 nm). Although the general method is well established, there is a lack of understanding the chemical processes that are triggered by the laser pulses, which may dictate the surface properties that are highly important in heterogeneous oxidation catalytic reactions. We observed the formation of radical oxygen species during LFL, which suggested that LFL is a physicochemical process that leads to particle size reductions and initiates oxidative processes. When the ionic strength in the nanoenvironment was increased, the oxidation of the first atomic layer saturated at 50%, whereby the surface charge density increases continuously. We found a correlation between the surface charge density after synthesis of colloidal nanoparticles and its behavior in catalysis. The properties of the laser-generated nanoparticles in the colloidal state appear to have predetermined the catalytic performance. We found that a smaller surface charge density of the usAu NPs was beneficial for the catalytic activity in CO and ethanol oxidation, while their peroxidase-like activity was affected less. The catalytic activity was 2 times higher for samples prepared by chloride-free LFL after ozone pretreatment compared to samples prepared in pure water.

Multicompartment micelles (MCMs) allow the simultaneous storage of multiple cargoes such as dyes, catalysts, or drugs, and have therefore gained attention in catalysis, nanotechnology, and nanomedicine. In the present work, we describe design rules to control the morphology of MCMs in water including spheres, cylinders, sheets, and vesicles. For that, we synthesized a series of poly(ethylene oxide) (PEO)-b-polystyrene (PS)-b-poly(methyl acrylate) (PMA) triblock terpolymers and systematically varied the length of the PS and PMA block. Using a stepwise hierarchical assembly process, we first form patchy precursor micelles in organic solvent with PS core and mixed PEO/PMA corona. In the second step, these micelles act as subunits, which assemble (or cluster) in water into MCMs, where PEO forms the stabilizing corona, PS the compartment, and PMA the inner core. We find that the shape of the final MCM can be predicted by ascribing a Janus balance to precursor micelles as the molar ratio of PEO to PMA, which provides a synthetic handle to target specific MCM morphologies.