In section S7 we made sure that using higher temperatures do not lead to any benefits for the synthesis. NPs synthesized at higher temperatures show relatively poor stability: the NPs tend to agglomerate and sediment over time, although the Au NPs obtained at higher temperatures using LiOH as the base tend to be slightly more stable which is attributed to a stabilization via the cation. These result confirm the preferred used of room temperature processes to develop syntheses with low energy requirement. It must be noted that the NPs once formed at room temperature are relatively stable when subjected to heat treatment even up to 80 °C, which highlights the stability of the formed surfactant-free NPs obtained using low viscosity solvent as the source of reducing agents.