The decrease of pristine Au at high electron flux densities shown in Figure and Figure appears only for (relatively) high initial HAuCl4 concentrations. This verifies that oxidative etching of gold itself is a function of the initial HAuCl4 concentration, as reported previously. As illustrated in Figure , this trend matches with our simulations, especially when a likely increase of concentration due to drying during the loading procedure is accounted for (not shown in Figure ). Note that for the reported electron flux density (> 10 7 e -nm²s -1 ), our simulation predicts the conversion of a substantial amount of solvent to H2, O2, and H2O2. As Kim et al. do not report any bubble formation, we assume that graphene membranes in the used graphene liquid cells significantly mitigate radiolysis effects due to their electrical conductivity. Hence, these experiments are noted at slightly reduced electron flux densities in The concentration dependency can be understood by the underlying chemistry: Gold reduction is mainly driven by solvated electrons (eh -) and H radicals which are primary radiolysis products in aqueous solutions and thus are independent on the initial HAuCl4 concentration.