The use of pulsed lasers to produce surfactant-free colloidal nanoparticles via laser ablation and fragmentation is well established. For laser ablation, the addition of support materials during laser ablation in liquids has shown size quenching effects, directly yielding supported and surfactant-free ~7 nm metal nanoparticle catalysts in a single step. However, its feasibility for laser fragmentation has barely investigated. This is why, in this work, we show that the fragmentation of initial, large gold nanoparticles (AuNPs), supported on graphene oxide (GO) already before laser fragmentation, leads to a significant size quenching effect, yielding GO-supported sub 3 nm gold clusters. The size-quenching was found to be particularly effective when the mass load of gold on GO was below 10 wt%, and a diluted Au/GO dispersion was used. In this context, the role of GO sheet-to-sheet distance and the overall gold concentration are discussed and used to predict experimental conditions which lead to a minimal AuNP size. The presented study therefore, not only optimizes the synthesis conditions to gain GO-supported clusters but also presents a new study concept to mechanistically investigate the post-synthesis growth processes during surfactant-free laser-based synthesis of nanoparticles.
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