Mixtures of alcohols for colloidal syntheses of nanoparticles: Benefits of [ethanol+glycerol] in alkaline water for surfactant-free gold nanoparticles

The full exploitation of nanoparticle (NP) properties require their controlled syntheses, ideally achieved by more sustainable strategies. We report on the benefits of using mixtures of ethanol and glycerol for the room temperature (RT) syntheses of stable surfactant-free colloidal gold (Au) NPs in alkaline water-alcohols solutions. Using [ethanol+glycerol] mixtures with a low amount of glycerol, e.g. only 2 v.%, improves the size control over the Au NPs and enables to lower the total alcohol content for a successful synthesis. The results provide solid foundation towards the rational development of green syntheses of surfactant-free colloidal NPs.