The final concentrations before taking into account volume contraction were typically 80 v.% water and 20 v.% alcohols in total, unless otherwise specified. The alcohols were ethanol (alternatively methanol) and/or glycerol in the indicated v.% (expressed before taking into account volume contraction that can happen in alcohol-water mixture such as ethanol-water mixtures due to hydrogen bonding). The other parameters were fixed as per optimal conditions previously established for ethanolmediated syntheses, i.e. 2 mM NaOH and 0.5 mM HAuCl4 for a total volume of 2 mL (before taking into account volume contraction). A NaOH/Au molar ratio of 4 was previously established as an optimal value in light of the equation of the reduction process. An overview and summary of the samples considered and their characteristics is provided in Table .